Obstentrics_Williams

Obstentrics_Williams. /' Perineal membrane with window that exposes striated urogenital sphincter mm. Dorsal n. & a. of Perineal n. & a. Perineal branch of cutaneous n. Inferior rectal n. & a. Gluteus maximus m. FIGURE 2-8 Pudendal nerve and vessels. (Reproduced with permission from Corton MM: Anatomy. In Hoffman BL, Schorge JO, Bradshaw KD, et al (eds): Williams Gynecology, 3rd ed. New York, McGraw-Hili Education, 2016.) posterior labial branches and muscular branches, which serve the labial skin and the anterior perineal triangle muscles, respectively. Last, the inferior rectal branch runs through the ischioanal fossa to supply the external anal sphincter, the anal mucosa, and the perianal skin (vlahakkanukrauh, 2005). The major blood supply to the perineum is via the internal pudendal artery, and its branches mirror the divisions of the pudendal nerve.


Obstentrics_Williams

Obstentrics_Williams. The nonpregnant uterus lies in the pelvic cavity between the bladder anteriorly and the rectum posteriorly. Almost the entire posterior wall of the uterus is covered by serosa, that is, visceral peritoneum (Fig. 2-9). The lower portion of this peritoneum forms the anterior boundary of the rectouterine cul-de-sac, or pouch of Douglas. Only the upper portion of the anterior uterine wall is covered by visceral peritoneum. At the caudal border of this portion, the peritoneum relects forward onto the bladder dome to create the vesicouterine pouch. As a result, the lower portion of the anterior uterine wall is separated from the posterior wall of the bladder only by a well-defined loose connective tissue layer-the vesicouterine space. Clinically, during cesarean delivery, the peritoneum of the vesicouterine pouch is sharply incised, and the vesicouterine space is entered. Dissection caudally within this space lifts the bladder safely of the lower uterine segment for hysterotomy and delivery


Obstentrics_Williams

Obstentrics_Williams. pouch is sharply incised, and the vesicouterine space is entered. Dissection caudally within this space lifts the bladder safely of the lower uterine segment for hysterotomy and delivery (Chap. 30, p. 573).


Obstentrics_Williams

Obstentrics_Williams. The uterus is pear shaped and consists of two major but unequal parts. The upper, larger portion is the body or corpus, whereas the lower smaller cervix projects into the vagina. The isthmus is the union site of these two. It is of special obstetrical significance because it forms the lower uterine segment during pregnancy. At each superolateral margin of the body is a uterine cornu, from which a fallopian tube emerges. This area also contains the origins of the round and ovarian ligaments. Between the points of fallopian tube insertion is the convex upper uterine segment termed the fundus. The bulk of the uterine body, but not the cervix, is muscle. The inner surfaces of the anterior and posterior walls lie almost in contact, and the cavity between these walls forms a mere slit. The nulligravid uterus measures 6 to 8 cm in length compared with 9 to 10 cm in multiparas. The uterus averages 60 g and typically weighs more in parous women (Langlois, 1970; Sheikhazadi,i2010).


Obstentrics_Williams

Obstentrics_Williams. Pregnancy stimulates remarkable uterine growth due to muscle iber hypertrophy. The uterine fundus, a previously flattened convexity between tubal insertions, now becomes dome shaped. Moreover, the round ligaments appear to insert at the junction of the middle and upper thirds of the organ. The fallopian tubes elongate, but the ovaries grossly appear unchanged. This portion of the uterus is cylindrical and has small apertures at each end-the internal and external cervical ora. The endocervical canal runs through the cervix and connects these ora. The cervix is divided into upper and lower portions by the vagina's attachment to its outer surface. he upper portionthe portio supravaginalis-begins at the internal os, which corresponds to the level at which the peritoneum is reflected up onto the bladder (Fig. 2-10). The lower cervical portion protrudes into the vagina as the portio vaginalis.


Obstentrics_Williams

Obstentrics_Williams. Before childbirth, the external cervical os is a small, regular, oval opening. After labor, especially vaginal childbirth, the orifice FIGURE 2-9 Anterior (A), right lateral (8), and posterior (C)views of the uterus of an adult woman. a = oviduct; b = round ligament; = ovarian ligament; Ur ureter. Tubal & ovarian branches of uterine & ovarian aa. External iliac a. Uterine a. Internal iliac a. Inferior epigastric a. & n. vaginalis of cervix FIGURE 2-10 Uterus, adnexa, and associated anatomy. (Reproduced with permission from Corton MM: Anatomy. In Hoffman BL, Schorge JO, Bradshaw KD, et al (eds): Williams Gynecology, 3rd ed. New York, McGraw-Hili Education, 2016.) is converted into a transverse slit that is divided such that there are the so-called anterior and posterior cervical lips. If torn deeply during labor or delivery, the cervix may heal in such a manner that it appears irregular, nodular, or stellate (Fig. 36-1, p. 653).


Obstentrics_Williams

Obstentrics_Williams. The cervical surface that radially surrounds the external os is called the ectocervix and is lined predominantly by nonkeratinized stratified squamous epithelium. In contrast, the endocervical canal is covered by a single layer of mucin-secreting columnar epithelium, which creates deep cleftlike infoldings or "glands." Commonly during pregnancy, the endocervical epithelium moves out and onto the ectocervix in a physiological process termed eversion (Chap. 4, p. 51). The cervical stroma is composed mainly of collagen, elastin, and proteoglycans, but very little smooth muscle. As described in Chapter 21 (p. 409), changes in the amount, composition, and orientation of these components lead to cervical ripening prior to labor onset. In early pregnancy, increased vascularity within the cervix stroma beneath the epithelium creates an ectocervical blue tint that is characteristic of Chadwick sign. Cervical edema leads to softening-Goodell sign, whereas isthmic softening is Hegar sign.


Obstentrics_Williams

Obstentrics_Williams. Most of the uterus is composed of myometrium, which contains smooth muscle bundles united by connective tissue with many elastic fibers. Interlacing myometrial ibers surround myometrial vessels and contract to compress these. This anatomy allows hemostasis at the placental site during the third stage of labor. he number of myometrial muscle ibers varies by location (Schwalm, 1966). Levels progressively diminish caudally such that, in the cervix, muscle makes up only 10 percent of the tissue mass. The uterine body's inner wall has relatively more muscle than its outer layers. And, in the anterior and posterior walls, the muscle content is greater than in the lateral walls. During pregnancy, the upper myometrium undergoes marked hypertrophy, but cervical muscle content does not change significantly.


Obstentrics_Williams

Obstentrics_Williams. The uterine cavity is lined with endometrium, which is composed of an overlying epithelium, invaginating glands, and a supportive, vascular stroma. As discussed in Chapter 5 (p. 83), the endometrium varies greatly throughout the menstrual cycle. This layer is divided into a functionalis layer, which is sloughed with menses, and a basalis layer, which serves to regenerate the functionalis layer following each menses. During pregnancy, the endometrium is termed decidua and undergoes dramatic hormonally driven alterations. Several ligaments extend from the uterine surface toward the pelvic sidewalls and include the round, broad, cardinal, and uterosacral ligaments (Figs. 2-10 and 2-11) . Despite their appellation, the round and broad ligaments provide no substantial uterine support, which contrasts with the cardinal and uterosacral ligaments.


Obstentrics_Williams

Obstentrics_Williams. he round ligament originates somewhat below and anterior to the origin of the fallopian tubes. Clinically, this orientation can aid fallopian tube identification during puerperal sterilization. External iliac a. & v. Lateral vaginal sulcus Adventitial layer of anterior vaginal wall Rectum


Obstentrics_Williams

Obstentrics_Williams. Lateral vaginal sulcus Adventitial layer of anterior vaginal wall Rectum FIGURE 2-1 1 Pelvic viscera and their connective tissue support. (Reproduced with permission from Corton MM: Anatomy. In Hoffman BL, Schorge JO, Bradshaw KD, et al (eds): Williams Gynecology, 3rd ed. New York, McGraw-Hili Education, 2016.) his is important if pelvic adhesions limit tubal mobility and thus, hinder fimbria visualization and tubal confirmation prior to ligation. Each round ligament extends laterally and down into the inguinal canal, through which it passes, to terminate in the upper portion of the ipsilateral labium majus. Sampson artery, a branch of the uterine artery, runs within this ligament. In nonpregnant women, the round ligament varies from 3 to 5 mm in diameter and is composed of smooth muscle bundles separated by ibrous tissue septa (Mahran, 1965). During pregnancy, these ligaments undergo considerable hypertrophy and increase appreciably in both length and diameter.


Obstentrics_Williams

Obstentrics_Williams. The broad ligaments are two winglike structures that extend from the lateral uterine margins to the pelvic sidewalls. Each broad ligament consists of a double-layer drape of peritoneum. The anterior and posterior layers of this drape are termed the anterior and posterior leaves, respectively. In forming the broad ligament, this peritoneum folds over structures extending from each cornu. Peritoneum that folds over the fallopian tube is termed the mesosalpinx, that around the round ligament is the mesoteres, and that over the ovarian ligament is the mesovarium. Peritoneum that extends beneath the imbriated end of the fallopian tube toward the pelvic wall forms the suspensory ligament or the infundibulopelvic ligament of the ovary. This contains nerves and the ovarian vessels, and during pregnancy, these vessels, especially the venous plexuses, are dramatically enlarged. Speciically, the diameter of the ovarian vascular pedicle increases from 0.9 cm to reach 2.6 cm at term (Hodgkinson,


Obstentrics_Williams

Obstentrics_Williams. these vessels, especially the venous plexuses, are dramatically enlarged. Speciically, the diameter of the ovarian vascular pedicle increases from 0.9 cm to reach 2.6 cm at term (Hodgkinson, 1953).


Obstentrics_Williams

Obstentrics_Williams. The cardinal ligament-also called the transverse cervicaliligament or Mackenrodt ligament-anchors medially to the uterus and upper vagina. The cardinal ligament is the thick base of the broad ligament. As such, during cesarean hysterectomy, sturdy clamps and suture are required for its transection and ligation. Each uterosacral ligament originates with a posterolateral attachment to the supravaginal portion of the cervix and inserts into the fascia over the sacrum, with some variations (Ramanah, 2012; Umek, 2004). These ligaments are composed of connective tissue, small bundles of vessels and nerves, and some smooth muscle. Covered by peritoneum, these ligaments form the lateral boundaries of the pouch of Douglas. The term parametrium is used to describe the connective tissues adjacent and lateral to the uterus within the broad ligament. Paracervical tissues are those adjacent to the cervix, whereas paracolpium is that tissue lateral to the vaginal walls.


Obstentrics_Williams

Obstentrics_Williams. During pregnancy, there is marked hypertrophy of the uterine vasculature, which is supplied principally from the uterine and ovarian arteries (see Fig. 2-10). The uterine artery, a main branch of the internal iliac artery-previously called the hypogastric artery-enters the base of the broad ligament. he uterine artery courses medially to the lateral side of the uterus. Approximately 2 cm lateral to the cervix, the uterine artery crosses over the ureter. This proximity is of great surgical signiicance, as the ureter may be injured or ligated during hysterectomy when the uterine vessels are clamped and ligated.


Obstentrics_Williams

Obstentrics_Williams. Once the uterine artery has reached the supravaginal portion of the cervix, it divides. The smaller cervicovaginal artery supplies blood to the lower cervix and upper vagina. The main uterine artery branch rurns abruptly upward and travels cephalad along the lateral margin of the uterus. Along its path, this main artery provides a branch of considerable size to the upper cervix and then numerous other medial branches serially penetrate the body of the uterus to form the arcuate arteries. As indicated by the name, each branch arches across the organ by coursing within the myometrium just beneath the serosal surface. Arcuate vessels from each side anastomose at the uterine midline. Radial artery branches originate at right angles from the arcuate arteries and travel inward through the myometrium, enter the endometrium/decidua, and branch there to become either basal arteries or coiled spiral arteries. he spiral arteries supply the funcrionalis layer. Also called the straight arteries,


Obstentrics_Williams

Obstentrics_Williams. enter the endometrium/decidua, and branch there to become either basal arteries or coiled spiral arteries. he spiral arteries supply the funcrionalis layer. Also called the straight arteries, the basal arteries extend only into the basalis layer.


Obstentrics_Williams

Obstentrics_Williams. As the uterine artery courses cephalad, it gives rise to Sampson artery of the round ligament. Just before the main uterine artery vessel reaches the fallopian rube, it divides into three terminal branches. The ovarian branch of the uterine artery forms an anastomosis with the terminal branch of the ovarian artery; Internal iliac a. the rubal branch makes its way through the mesosalpinx and supplies part of the fallopian tube; and the fundal branch penetrates the uppermost uterus.


Obstentrics_Williams

Obstentrics_Williams. Internal iliac a. the rubal branch makes its way through the mesosalpinx and supplies part of the fallopian tube; and the fundal branch penetrates the uppermost uterus. In addition to the uterine artery, the uterus receives blood supply from the ovarian artery (see Fig. 2-10). This artery is a direct branch of the aorta and enters the broad ligament through the infundibulopelvic ligament. At the ovarian hilum, it divides into smaller branches that enter the ovary. As the ovarian artery runs along the hilum, it also sends several branches through the mesosalpinx to supply the fallopian rubes. Its main stem, however, traverses the entire length of the broad ligament toward the uterine cornu. Here, it forms an anastomosis with the ovarian branch of the uterine artery. This dual uterine blood supply creates a vascular reserve to prevent uterine ischemia if ligation of the uterine or internal iliac artery is performed to control postpartum hemorrhage.


Obstentrics_Williams

Obstentrics_Williams. Uterine veins accompany their respective arteries. As such, the arcuate veins unite to form the uterine vein, which empties into the internal iliac vein and then the common iliac vein. Some of the blood from the upper uterus, the ovary, and the upper part of the broad ligament is collected by several veins. Within the broad ligament, these veins form the large pampiniform plexus that terminates in the ovarian vein. From here, the right ovarian vein empties into the vena cava, whereas the left ovarian vein empties into the left renal vein. Ureter Inferior mesenteric a. Ovarian a. External iliaca. Iliolumbar a. Obturatora. Accessory obturator a. Superior rectal a. Inferior epigastric a. Round ligament (cut) Lateralsacral a. Medial umbilical ligament Superior gluteal a. Superior vesical aa. Inferior gluteal a. Inferior vesical a. Vaginal a. Internal pudendala. Uterine a. (ascending branch) Sampson a.toround ligament Uterus


Obstentrics_Williams

Obstentrics_Williams. Superior vesical aa. Inferior gluteal a. Inferior vesical a. Vaginal a. Internal pudendala. Uterine a. (ascending branch) Sampson a.toround ligament Uterus FIGURE 2-12 Pelvic arteries. (Reproduced with permission from Corton MM: Anatomy. In Hoffman BL, Schorge JO, Bradshaw KD, et al (eds): Williams Gynecology, 3rd ed. New York, McGraw-Hili Education, 2016.)


Obstentrics_Williams

Obstentrics_Williams. Williams Gynecology, 3rd ed. New York, McGraw-Hili Education, 2016.) Blood supply to the pelvis is predominantly provided by branches of the internal iliac artery (Fig. 2-12). These branches are organized into anterior and posterior divisions, and subsequent branches are highly variable between individuals. The anterior division provides blood supply to the pelvic organs and perineum and includes the inferior gluteal, internal pudendal, middle rectal, vaginal, uterine, and obturator arteries, as well as the umbilical artery and its continuation as the superior vesical artery. The posterior division branches extend to the buttock and thigh and include the superior gluteal, lateral sacral, and iliolumbar arteries. For this reason, during internal iliac artery ligation, many advocate ligation distal to the posterior division to avoid compromised blood low to the areas supplied by this division (Bleich, 2007).


Obstentrics_Williams

Obstentrics_Williams. The lymphatics from the uterine corpus are distributed to two groups of nodes. One set of vessels drains into the internal iliac nodes. The other set, after joining lymphatics from the ovarian region, terminates in the paraaortic lymph nodes. Lymphatics from the cervix terminate mainly in the internal iliac nodes, which are situated near the bifurcation of the common iliac vessels. As a brief review, the peripheral nevous system is divided into a somatic division, which innervates skeletal muscle, and an autonomic division, which innervates smooth muscle, cardiac muscle, and glands. Pelvic visceral innervation is predominantly autonomic, which is further divided into sympathetic and parasympathetic components.


Obstentrics_Williams

Obstentrics_Williams. Sympathetic innervation to pelvic viscera begins with the superior hypogastric plexus, also termed the presacral nerve (Fig. 2-13). Beginning below the aortic bifurcation and extending downward retroperitoneally, this plexus is formed by sympathetic fibers arising from spinal levels TID through L2• At the level of the sacral promontory, this superior hypogastric plexus divides into a right and a left hypogastric nerve, which run downward along the pelvis sidewalls (Ripperda, 20i1i5). Fibers to vestibular bulbs FIGURE 2-13 Pelvic innervation. (Reproduced with permission from Corton MM: Anatomy. In Hofman BL, Schorge JO, Bradshaw KD, et al (eds): Williams Gynecology, 3rd ed. New York, McGraw-Hili Education, 2016.)


Obstentrics_Williams

Obstentrics_Williams. Williams Gynecology, 3rd ed. New York, McGraw-Hili Education, 2016.) In contrast, parasympathetic innervation to the pelvic viscera derives from neurons at spinal levels 52 through 54' heir axons exit as part of the anterior rami of the spinal nerves for those levels. These combine on each side to form the pelvic splanchnic nerves, also termed nervi erigentes.


Obstentrics_Williams

Obstentrics_Williams. Blending of the two hypogastric nerves (sympathetic) and the two pelvic splanchnic nerves (parasympathetic) gives rise to the inferior hypogastric plexus, also termed the pelvic plexus. his retroperitoneal plaque of nerves lies at the 54 and 55 level (Spackman, 2007). From here, fibers of this plexus accompany internal iliac artery branches to their respective pelvic viscera. Thus, the inferior hypogastric plexus divides into three plexuses. he vesical plexus innervates the bladder, and the middle rectal plexus travels to the rectum. he uterovaginal plexus, also termed F rankenhauser plexus, reaches the proximal fallopian tubes, uterus, and upper vagina. Extensions of the inferior hypogastric plexus also reach the perineum along the vagina and urethra to innervate the clitoris and vestibular bulbs (Montoya, 2011). Of these, the uterovaginal plexus is composed of variably sized ganglia, but particularly of a large ganglionic plate that is situated on either side of the cervix,


Obstentrics_Williams

Obstentrics_Williams. vestibular bulbs (Montoya, 2011). Of these, the uterovaginal plexus is composed of variably sized ganglia, but particularly of a large ganglionic plate that is situated on either side of the cervix, proximate to the uterosacral and cardinal ligaments (Ramanah, 2012).


Obstentrics_Williams

Obstentrics_Williams. For the uterus, most of its aferent sensory fibers ascend through the inferior hypogastric plexus and enter the spinal cord via T 10 through T 12 and L] spinal nerves. These transmit the painful stimuli of contractions to the central nervous system. For the cervix and upper part of the birth canal, sensory nerves pass through the pelvic splanchnic nerves to the second, third, and fourth sacral nerves. Last, those from the lower portion of the birth canal pass primarily through the pudendal nerve. Anesthetic blocks used during delivery target these levels of innervation. long the pelvic sidewall, each ovary usually rests in the ovarian fossa ofWaldeyer, which is a slight depression between the external and internal iliac vessels. During childbearing years, ovaries variably measure 2.5 to 5 cm in length, 1.5 to 3 cm in width, and 0.6 to 1.5 cm in thickness.


Obstentrics_Williams

Obstentrics_Williams. he ovarian ligament, also called the uteroovarian ligament, originates from the upper posterolateral portion of the uterus, just beneath the tubal insertion level, and extends to the uterine pole of the ovary (see Fig. 2-10). Measuring a few centimeters long and 3 to 4 mm in diameter, this ligament is made up of muscle and connective tissue and is covered by peritoneum-the mesovarium. Blood supply reaches the ovary through this double-layered mesovarium to enter the ovarian hilum. The ovary consists of an outer cortex and inner medulla. In young women, the cortex is smooth, has a dull white surface, and is lined by single layer of cuboidal epithelium, the germinal epithelium ofWaldeyer. his epithelium is supported by a connective tissue condensation, the tunica albuginea. Beneath this, the ovarian cortex contains oocytes and developing follicles. The medulla is composed of loose connective tissue, numerous arteries and veins, and a small amount of smooth muscle ibers.


Obstentrics_Williams

Obstentrics_Williams. The ovaries are supplied with both sympathetic and parasympathetic nerves. he sympathetic nerves are derived primarily from the ovarian plexus that accompanies the ovarian vessels and originates in the renal plexus. Others are derived from the plexus that surrounds the ovarian branch of the uterine artery. Parasympathetic input is from the vagus nerve. Sensory aferents follow the ovarian artery and enter at T]o spinal cord level.


Obstentrics_Williams

Obstentrics_Williams. Also called oviducts, these serpentine tubes extend laterlly 8 to 14 cm from the uterine cornua. hey are anatomically classified along their length s an interstitial portion, isthmus, ampulla, and inundibulum (Fig. 2-14). vIost proximal, the interstitial portion is embodied within the uterine muscular wall. Next, the narrow 2-to 3-mm wide isthmus widens gradually into the 5-to 8-mm wide ampulla. Last, the inundibulum is the unnel-shaped fimbriated distal extremity of the tube, which opens into the abdominal cavity. These latter three extrauterine portions are covered by the mesosalpinx at the superior margin of the broad ligament.


Obstentrics_Williams

Obstentrics_Williams. In cross section, the extrauterine fallopian tube contains a mesosalpinx, myosalpinx, and endosalpinx. he outer of these, the mesosalpinx, is a single-cell mesothelial layer unctioning as visceral peritoneum. In the myosalpinx, smooth muscle is arranged in an inner circular and an outer longitudinal layer. The tubal musculature undergoes rhythmic contractions constantly, the rate of which varies with cyclical ovarian hormonal changes.


Obstentrics_Williams

Obstentrics_Williams. The tubal mucosa or endosalpinx is a single layer of columnar epithelium composed of ciliated, secretory, and intercalary cells resting on a sparse lamina propria. Clinically, its close proximity to the underlying myosalpinx contributes to easy invasion by ectopic trophoblast. The tubal mucosa is arranged in longitudinal folds that become progressively more complex toward the fimbria. In the ampulla, the lumen is occupied almost completely by the arborescent mucosa. The current produced by the tubal cilia is such that the direction of flow is toward the uterine cavity. Tubal peristalsis created by cilia and muscular layer contraction is believed to be an important factor in ovum transport (Croxatto, 2002).


Obstentrics_Williams

Obstentrics_Williams. he tubes are supplied richly with elastic tissue, blood vessels, and lymphatics. Their sympathetic innervation is extensive, in contrast to their parasympathetic innervation. This nerve supply derives partly from the ovarian plexus and partly from the uterovaginal plexus. Sensory aferent ibers ascend to T]o spinal cord levels. Anteriorly, the bladder rests against the inner surface of the pubic bones and then, as it fills, also against the anterior abdominal wall. Posteriorly, it rests against the vagina and cer vix. he bladder is divided into a dome and a base approximately at the level of the ureteral oriices. The dome is thin walled and distensible, whereas the base is thicker and undergoes less distention during filling. The vesical trigone lies in the bladder base and contains both ureteral oriices and the internal


Obstentrics_Williams

Obstentrics_Williams. A B FIGURE 2-14 The fallopian tube of an adult woman with cross-sectioned illustrations of the gross structure in several portions: (A) isthmus, (B) ampUlla, and (C) infundibulum. Below these are photographs of corresponding histological sections. (Used with permission from Dr. Kelley S. Carrick.) urinary meatus (see Fig. 2-11). he urethral lumen begins at this meatus and then courses through the bladder base for less than 1 cm. This region where the urethral lumen traverses the bladder base is called the bladder neck. The bladder wall consists of coarse bundles of smooth muscle known as the detrusor muscle, which extends into the proximal part of the urethra. A submucosal layer intervenes between this detrusor muscle and the mucosa. he bladder mucosa consists of transitional epithelium and underlying lamina propria.


Obstentrics_Williams

Obstentrics_Williams. The blood supply to the bladder arises from the superior vesical arteries, which are branches of the patent portion of the umbilical artery, and from the middle and inferior vesical arteries, which, when present, often arise from either the internal pudendal or the vaginal arteries (see Fig. 2-12). The nerve supply to the bladder arises from the vesical plexus, a component of the inferior hypogastric plexus (see Fig. 2-13).


Obstentrics_Williams

Obstentrics_Williams. As the ureter enters the pelvis, it crosses over the bifurcation of the common iliac artery and passes just medial to the ovarian vessels (see Fig. 2-10). As the ureter descends into the pelvis, it lies medial to the internal iliac branches and anterolateral to the uterosacral ligaments. The ureter then traverses through the cardinal ligament approximately 1 to 2 cm lateral to the cervix. Near the level of the uterine isthmus, it courses below the uterine artery and travels anteromedially toward the bladder base. In this path, it runs close to the upper third of the anterior vaginal wall (Rahn, 2007). Finally, the ureter enters the bladder and travels obliquely for approximately 1.5 cm before opening at the ureteral oriices.


Obstentrics_Williams

Obstentrics_Williams. The pelvic ureter receives blood supply from the vessels it passes: the common iliac, internal iliac, uterine, and superior vesical vessels. The ureter's course runs medial to these vessels, and thus its blood supply reaches the ureter from lateral sources. This is important during ure teral isolation. Vascular anastomoses on the connective tissue sheath enveloping the ureter form a longitudinal nenvork of vessels. The pelvis is composed of four bonesthe sacrum, coccyx, and two innominate bones. Each innominate bone is formed by the fusion of three bones-the ilium, ischium, and pubis (Fig. 2-15). Both innominate bones are joined to the sacrum at the sacroiliac synchondroses and to one another at the symphysis pubis.


Obstentrics_Williams

Obstentrics_Williams. Anteriorly, the pelvic bones are joined together by the symphysis pubis. This structure consists of fibrocartilage and the superior and inferior pubic ligaments. The latter ligament is frequently designated the arcuate ligament of the pubis. Posteriorly, the pelvic bones are joined by articulations between the sacrum and the iliac portion of the innominate bones to form the sacroiliac joints.


Obstentrics_Williams

Obstentrics_Williams. The pelvic joints in general have a limited degree of mobility. However, during pregnancy, these joints relax remarkably at term. As one result, upward gliding of the sacroiliac joint, which is greatest in the dorsal lithotomy position, may increase the diameter of the outlet by 1.5 to 2.0 cm for delivery (Borell, 1957). Sacroiliac joint mobility also likely aids the McRoberts maneuver to release an obstructed shoulder in cases of shoulder dystocia (Chap. 27, p. 521). These changes may also contribute to the success of the modified squatting position to hasten second-stage labor (Cardosi, 1989). The squatting position may increase the interspinous diameter and the pelvic outlet diameter (Russell, 1969, 1982).


Obstentrics_Williams

Obstentrics_Williams. FIGURE 2-15 The innominate bone is composed of the pubis (brown), ischium (red), and ilium (blue). Of the three anteroposterior diameters of the pelvic inlet, only the diagonal conjugate can be measured clinically. The important obstetrical conjugate is derived by subtracting 15 cm from the diagonal conjugate. • Planes and Diameters of the Pelvis The pelvis is conceptually divided into false and true components. The false pelvis lies above the linea terminalis, and the true pelvis is below this boundary (Fig. 2-16). he false pelvis is bounded posteriorly by the lumbar vertebra and laterally by the iliac fossa. In front, the boundary is formed by the lower portion of the anterior abdominal wall. he pelvis is described as having four imaginary planes: 1. The plane of the pelvic inlet-the superior strait. 2. The plane of the pelvic outlet-the inferior strait. 3. he plane of the midpelvis-the least pelvic dimensions. 4.


Obstentrics_Williams

Obstentrics_Williams. The plane of the pelvic inlet-the superior strait. 2. The plane of the pelvic outlet-the inferior strait. 3. he plane of the midpelvis-the least pelvic dimensions. 4. he plane of greatest pelvic dimension-of no obstetrical significance. he pelvic inlet, also called the superior strait, is the superior plane of the true pelvis. It is bounded posteriorly by the promontory and alae of the sacrum, laterally by the linea terminalis, and anteriorly by the horizontal pubic rami and the symphysis pubis. During labor, fetal head engagement is deined by the fetal head's biparietal diameter passing through this plane.


Obstentrics_Williams

Obstentrics_Williams. Four diameters of the pelvic inlet are usually described: anteroposterior, transverse, and two oblique diameters. Of these, distinct anteroposterior diameters have been described using specific landmarks. Most cephalad, the anteroposterior diameter, termed the true conjugate, extends from the uppermost margin of the symphysis pubis to the sacral promontory (see Fig. 2-15). he clinically important obstetrical conjugate is the shortest distance between the sacral promontory and the symphysis pubis. Normally, this measures 10 cm or more, but unfortunately, it cannot be measured directly with examining fingers. hus, the obstetrical conjugate is estimated indirectly by subtracting 1.5 to 2 cm from the diagonal conjugate. To measure the diagonal conjugate, a hand with the palm oriented laterally extends its index finger to the promontory. The distance from the fingertip to the point at which the lowest margin of the symphysis strikes the same inger's base is the diagonal conjugate.


Obstentrics_Williams

Obstentrics_Williams. he transverse diameter is constructed at right angles to the obstetrical conjugate and represents the greatest distance between the linea terminalis on either side (see Fig. 2-16). It usually intersects the obstetrical conjugate at a point approximately 5 cm in front of the promontory and measures approximately 13 cm. The midpelvis is measured at the level of the ischial spines, also called the midplane or plane of least pelvic dimensions (see Fig. 2-16). During labor, the degree of fetal head descent into the true pelvis may be described by station, and the midpelvis and ischial spines serve to mark zero station. The interspinous diameter is 10 cm or slightly greater and is usually the smallest pelvic diameter. The anteroposterior diameter through the level of the ischial spines normally measures at least 11.5 cm.


Obstentrics_Williams

Obstentrics_Williams. The pelvic outlet consists of two approximately triangular areas whose boundaries mirror those of the perineal triangle described earlier (p. 19). They have a common base, which is a line drawn between the two ischial tuberosities. The apex of the posterior triangle is the tip of the sacrum, and the (, .Iium FIGURE 2-16 Axial view of a normal female pelvis. The clinically important obstetrical conjugate and transverse diameter of the pelvic inlet are illustrated. The interspinous diameter of the mid pelvis is also marked. Anthropotd ,.,• Intermediates • .. 4 FIGURE 2-17 The four parent pelvic types of the Caldwell-Moloy classification. A line passing through the widest transverse diameter divides the inlets into posterior (P) and anterior (A) segments.


Obstentrics_Williams

Obstentrics_Williams. FIGURE 2-17 The four parent pelvic types of the Caldwell-Moloy classification. A line passing through the widest transverse diameter divides the inlets into posterior (P) and anterior (A) segments. lateral boundaries are the sacrotuberous ligaments and the ischial tuberosities. 'he anrerior triangle is formed by the descending inferior rami of rhe pubic bones. These rami unite at an angle of 90 [0 100 degrees ro form a rounded arch under which the fetal head must pass. Unless there is Signiicant pelvic bony disease, rhe pelvic ourler seldom obstructs vaginal delivery.


Obstentrics_Williams

Obstentrics_Williams. The Caldwell-Moloy (I933, 1934) anaromical classiication of rhe pelvis is based on shape, and its concepts aid an understanding of labor mechanisms. Speciically, the grearesr transverse diameter of rhe inler and its division into alHerior and posterior segmelHs are used to classiy rhe pelvis as gynecoid, anthropoid, android, or platypelloid. The posterior segmelH determines the type of pelvis, whereas the anterior segment determines the tendency. These are both determined because many pelves are nor pure but are mixed types. For example, a gynecoid pelvis with an android tendency means that rhe posterior pelvis is gynecoid and the anterior pelvis is android shaped. From viewing the four basic types in 2-17I, the coniguration of the gynecoid pelvis would intuitively seem suited for delivery of most fetuses. Indeed, Caldwell (I 939) reported [hac rhe gynecoid pelvis was found in almost half of women.


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Obstentrics_Williams. Barher MD, Bremer E, Thor KB, er al: Innervation of the female levator ani muscles. Am J Obsrer Gynecol 187:64, 2002 Beer GM, Schuster A, Seifert B, et al: 1he normal width of the linea alba in nulliparous women. Clin Anar 22(6):706, 2009 Bleich AT, Rahn DO, Wieslander CK, et al: Posterior division of the internal iliac artery: anatomic variations and clinical applications. Am J Obstet Gynecol 197:658.e1, 2007 Borell U, Fenstrom I: Movements at the sacroiliac joillls and their importance to changes in pelvic dimensions during parturition. Acta Obstet Gynecol Scand 36:42, 1957 Caldwell WE, 'vloloy He: Anatomical variations in the female pelvis and their efect in Jabor with a suggested classiication. Am J Obstet GynecoJ 26:479, 1933 Caldwell WE, Moloy HC, D'Esopo DA: Further studies on the pelvic architecture.m J Obstet Gynecol 28:482, 1934


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Obstentrics_Williams. Caldwell WE, Moloy HC, D'Esopo DA: Further studies on the pelvic architecture.m J Obstet Gynecol 28:482, 1934 Caldwell WE, Moloy HC, Swenson PC The use of [he roentgen ray in obstetrics, I. Roentgen pelvimetry and cephalometry; technique of pdviroenrgenography. AJR 41 :305, 1939 Corton tdM: Anatomy. In Hoffman BL, SchorgeeJO, Bradshaw KD, et al (cds): Williams Gynecology, 3rd ed. New York, McGraw-Hill Education, 2016 Corton t"tM: Anatomy of the pelvis: how the pelvis is built for support. Clin Ohstct Gynecol 48:611, 2005 Croxatto HB: PhysioloY of gamete and embryo transport through the fallopian tube. Reprod Biomed Online 4(2): I60, 2002 DeLancey JO, Toglia MR, Peucchini D: Imernal and extern;l] anal sphincter anatomy as it relates to midline obstetric lacerations. Obstct Gynccol 90m4,e1997 DeLancey JOL, Keaney R, Chou Q, et al: The appearance of levaror ani muscle abnormalities in magnetic resonance images after vaginal delivery. Obstet Cyneco] 101 :46, 2003


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Obstentrics_Williams. DeLancey JOL, Keaney R, Chou Q, et al: The appearance of levaror ani muscle abnormalities in magnetic resonance images after vaginal delivery. Obstet Cyneco] 101 :46, 2003 Dietz HP, Simpson JM: Levator trauma is associated with pelvic organ prol,p", BjOG lI5(8)m9, 2008 Fusco p, Scimia P, Paladini G, et al: Transversus abdominis plane block for analgesia after Cesarean delivery. A systematic review. Minerva Anesrcsioi SI(2H95,e2015 Gardosi J, Hutson N, Lynch CB: Randomised, comrolled trial of squatting in the second stage of labour. Lancet 2:74,e1989 Ginger VA, Cold j, Yang CC: Structure and innervation of the labia minora: more than minor skin folds. Female Pelvic l·led Reconsrr Surg 17(4):180, 201la Ginger VA, Cold j, Yang CC: Surgical anatomy of the dorsal nerve of the clitoris. Neuroural Urodyn 30(3):412, 2011 b


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Obstentrics_Williams. Ginger VA, Cold j, Yang CC: Surgical anatomy of the dorsal nerve of the clitoris. Neuroural Urodyn 30(3):412, 2011 b Hawkins JL: Anesthesia for the pregnant woman. In Yeomans ER, Hofman BL, Gilstrap LC Ill, et al: Cunningham and Gilsuaps's Operative Obstetrics, 3rd ed. New York, McGraw-Hill Education, 2017 Hodgkinson CP: Physiology of the ovarian veins during pregnancy. Obstet Gynecol 1 (1):26, 19S3 Kearney R, Sawhney R, Delancey )0: Levator ani muscle anatomy evaluated by origin-insertion pairs. Obstet Gynecol 104:168,e2004 Kim SO, Oh K), Lee HS, et al: Expression of aquaporin water channels in the vagina in premenopausal women.e) Sex Med 8(7):I92S, 2011 Langlois PL: The si'Le of the normal uterus.e) Reprod Med 4:220, 1970


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Obstentrics_Williams. Langlois PL: The si'Le of the normal uterus.e) Reprod Med 4:220, 1970 Larson KA, Yousuf A, Lewicky-Gaupp C, et al: Perineal body anatomy in living women: 3-dimensional analysis using thin-slice magnetic resonance imaging. Am J Obstet GynecoI203(S):494.elS, 2010 ien KC, Morgan OM, Delancey )0, et al: Pudendal nerve stretch during vaginal birth: a 3D computer simulation. m J Obstet Gynecol 192(S): 1669, 200S Lloyde). Crouch NS, Minto CL, et al: Female genital appearance: "normality" unfold" BjOG 112(5),643,e2005 Loukas M, r,1yers C, Shah R, et al: Arcuate line of the rectus sheath: clinical approach. Anat Sci Int 83(3):140, 2008 Mahakkanukrauh p, Surin p, Vaidhayakarn P: Anatomical study of the pudendal nerve adjacent to the sacrospinous ligament. Clin Anat 18:200, 200S Mahran '1: The microscopic anatomy of the round ligament. J Obstet Gynae col Br Commomv 72:614, 1965


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Obstentrics_Williams. Maldonado rA, Chin K, Garcia A, et 1: Anatomic variations of pudendal nerve within pelvis and pudendal canal: clinical applications. m ) Obstet GynecoIe213(S):727,e20IS Mei W, lin C, Feng L, et al: Bilateral ultrasound-guided transversus abdominis plane block combined with iliOinguinal-iliohypogastric nerve block for cesarean delivey anesthesia. Anesth Analg 113(1):134,2011 Mirilas p, Skandalakis )E: Urogenital diaphragm: an erroneous concept casting its shadow over the sphincter urethrae and deep perineal space. J m Coli Surg 198:279,e2004 Montoya TI, Calver L, Carrick S, et al: Anatomic relationships of the pudendal nerve branches. Am J Obstet Gynecol 20S(S):S04.el, 2011 Rahn DO, Bleich AT, Wai CY, et al: Anatomic relationships of the distal third of the pelvic ureter, trigone, and urethra in unembalmed female cadavers. Am J Obstet Gynecol 197(6):668.e 1, 2007


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Obstentrics_Williams. Rahn DO, Bleich AT, Wai CY, et al: Anatomic relationships of the distal third of the pelvic ureter, trigone, and urethra in unembalmed female cadavers. Am J Obstet Gynecol 197(6):668.e 1, 2007 Rahn DD, Phelan IN, Roshanravan SM, et al: Anterior abdominal wall nerve and vessel anatomy: clinical implications for gynecologic surgery. m ) Obstet Gyneol 202(3):234.el, 2010 Ramanah R, Berger MB, Parrarre BM, et al: Anatomy and histology of apical support: a literature review concerning cardinal and uterosacral ligaments. Int Urogynecole) 23(11):e1483, 2012 Ripperda CM, Jackson A, Phelan )N, et al: Anatomic relationships of the pelvic autonomic nervous system in female cadavers: clinical applications to pelvic surgery. Oral presentation at AUGS Annual Scientiic Meeting, 13-17 October, 20lS Russell )G: iVloulding of the pelvic outlet. J Obstet Gynaecol Br Commonw 76:817.e1969 Russell JG: The rationale of primitive delivery positions. B)OG 89:712, 1982


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Obstentrics_Williams. Russell )G: iVloulding of the pelvic outlet. J Obstet Gynaecol Br Commonw 76:817.e1969 Russell JG: The rationale of primitive delivery positions. B)OG 89:712, 1982 Santoro GA, Shobeiri SA, Petros PP, et al: Perineal body anatomy seen by three-dimensional endovaginal ultrasound of asymptomatic nulliparae. Colorectal Dis 18(4):400, 2016 Schober J, A.lrdsma N, lvlayoglou L, et al: Terminal innervation of female genitalia, cutaneous sensory receptors of the epithelium of the labia minora. Clin Anat 28(3):392, 20lS Schwalm H, Dubrauszky V: The structure of the musculature of the human uterus-muscles and connective tissue. m) Obstet Cynecol 94:391, 1966 Schwertner-Tiepelmann N, Thakar R, Sultan AH, et al: Obstetric levator ani muscle injuries: current status. Ultrasound Obstet GynecoI39(4):372, 2012 Shaik A, Doss SH: Pudendal canal: surgical anatomy and clinical implications. m Surg 6S: 176, 1999


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Obstentrics_Williams. m Surg 6S: 176, 1999 Shaik A, Sibai OE, Shaik A, et al: A novel concept for the surgical anatomy of the perineal body. Dis Colon Rectum SO(l2):2120, 2007 Sheikhazadi A, Sadr SS, Ghadyani MH, et al: Study of the normal internal organ weights in Tehran's population.) Forensic Leg Med 17(2):78, 2010 Spackman R, Wrigley B, RobertS A, et al: The inferior hypogastriC plexus: a diferent view.) Obstet Gynaecoi 27(2):130, 2007 Tawik MM, Mohamed YM, Elbadrawi E, et al: Transversus abdominis plane block versus wound iniltration for analgeSia after cesarean delivery: a randomized controlled trial. Anesth Analg 124(4):1291, 2017 Tolcher :lC, Nitsche)F, Arendt f, et al: Spontaneous rectus sheath hematoma pregnancy: case report and revie' of the literature. Obstet Cynecol Su� 65(8),517, 2010 Umek H, Morgan DM, Ashton-Miller )A, et al: Quantitative analysis of uterosacral ligament origin and insertion poims by magnetic resonance imaging. Obstet Gynecol 103:447,e2004


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Obstentrics_Williams. Umek H, Morgan DM, Ashton-Miller )A, et al: Quantitative analysis of uterosacral ligament origin and insertion poims by magnetic resonance imaging. Obstet Gynecol 103:447,e2004 VerkaufBS, Von Thron J, O'Brien WF: Clitoral size in normal women. Obstet Gynecol 80(1):41, 1992 Wai C, Bhatia K, Clegg I: RecTUS sheath haematoma: a rare cause of abdominal pain in pregnancy. 1m) Obstet Anesth 24(2): 194, 2015 Weber M, Walters MD: Anterior vaginal prolapse: review of anatomy and techniques of surgical repair. Obstet Gynecol 89:311, 1997 (leidner AC, Jamison MG, Branham V, et 1: Neuropathic injury to the levator ani occurs in I in 4 primiparous women. m J Obstet Gynecole19S: 18SI, 2006 Whiteside JL, Barber MD: IIlioinguinalliliohypogastric neurectomy for management of inrractable right lower quadrant pain ater cesarean section: a case report. J Reprod IvIed SO(l 1):8S7, 200S


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Obstentrics_Williams. Whiteside JL, Barber MD: IIlioinguinalliliohypogastric neurectomy for management of inrractable right lower quadrant pain ater cesarean section: a case report. J Reprod IvIed SO(l 1):8S7, 200S Whiteside JL, Barber MD, Walters MD, et 1: Anatomy of ilioinguinal and iliohypogastric nerves in relation to trocar placement and low transverse incisions. m) Obsret Gynecol 189: 1574, 2003 Wilkinson E), Massoll NA: Benign diseases of the vulva. In Kurman R), Ellenson LH, Ronnen BM (eds): Blaustein's Pathology of the Female Genital Tract, 6th ed. New York, Springer, 2011, p 3 Wolfson A, Lee A), Wong P, et al: Bilateral multi-injection iliohypogastricilioinguinal nerve block in conjunction with neuraxial morphine is superior to neuraxial morphine alone for postcesarean analgeSia. J Clin Anesth 24(4),298,e2012 GENITOURINARY TRACT DEVELOPMENT ..... . .. 33 SEXUAL DIFFERENTIATION .. . ..... ............. 38..... DISORDERS OF SEX .... . ... . 38..........


Obstentrics_Williams

Obstentrics_Williams. GENITOURINARY TRACT DEVELOPMENT ..... . .. 33 SEXUAL DIFFERENTIATION .. . ..... ............. 38..... DISORDERS OF SEX .... . ... . 38.......... BLADDER AND PERINEAL ABNORMALITIES ...... , ... 41 MULLERIAN ABNORMALITIES .... .. ..... ....... 41...... UTERINE FLEXION ......... , .............. , .. , ... 46 Abnormalities in the development or fusion of one or both MUllerian ducts may result in maormations which sometimes possess an obstetrical signicance. Pregnancy may be associated with anyione of these maormations, provided an ovum be cast of rom the ovaries and no serious obstacle be opposed to the upward passage of the spermatozoa and their subsequent union with it. -]. Whitridge Williams (1903)


Obstentrics_Williams

Obstentrics_Williams. -]. Whitridge Williams (1903) In females, the external genitalia, gonads, and miillerian ducts each derive from diferent primordia and in close association with the urinary tract and hindgut. Abnormal embryogenesis during this process is thought to be multifactorial and can create sporadic anomalies. Several of these can lead to infertility, subfertility, miscarriage, or preterm delivery. Thus, knowledge of genitourinary system development is essential. • Embryology of the Urinary System Between the 3rd and 5th gestational weeks, an elevation ofintermediate mesoderm on each side of the fetus-the urogenital ridge-begins development into the urogenital tract. Subsequently, the urogenital ridge divides into the genital ridge, destined to become the ovary, and into the nephrogenic ridge (Fig. he nephrogenic ridges develop into the mesonephros (mesonephric kidney) and paired mesonephric ducts, also termed wolian ducts, which connect to the cloaca.


Obstentrics_Williams

Obstentrics_Williams. he nephrogenic ridges develop into the mesonephros (mesonephric kidney) and paired mesonephric ducts, also termed wolian ducts, which connect to the cloaca. The early urinary tract develops from the mesonephros and its mesonephric ducts (Fig. 3-2A). Recall that evolution of the renal system passes sequentially through the pronephric and mesonephric stages to reach the permanent metanephric system. Between the 4th and 5th weeks, each mesonephric duct gives rise to a ureteric bud, which grows cephalad toward its respective mesonephros (Fig. 3-2B), As each bud lengthens, it induces diferentiation of the metanephros, which will become the inal kidney (Fig. 3-2C). Each mesonephros degenerates near the end of the first trimester, and without testosterone, the mesonephric ducts regress as well.


Obstentrics_Williams

Obstentrics_Williams. he cloaca begins as a common opening for the embryonic urinary, genital, and alimentary tracts. By the 7th week it becomes divided by the urorectal septum to create the rectum and the urogenital sinus (Fig. 3-2D). The urogenital sinus is considered in three parts: (1) the cephalad or vesicle portion, which forms the urinary bladder; (2) the middle or pelvic portion, which creates the female urethra; and (3) the caudal or phallic part, which gives rise to the distal vagina and to the greater vestibular (Bartholin) and paraurethral glands.


Obstentrics_Williams

Obstentrics_Williams. • Embryology of the Genital Tract he fallopian tubes, uterus, and upper vagina derive from the miillerian ducts, also termed paramesonephric ducts, which form adjacent to each mesonephros (see Fig. 3-2B). These ducts extend downward and then turn medially to meet and fuse together in the midline. he uterus is formed by this union of the two miillerian ducts at approximately the 10th week (Fig. 3-2E). Fusion to create the uterus begins in the middle and then extends both caudally and cephalad. With cellular FIGURE 3-2 Embryonic development of the female genitourinary tract (A-F). (Reproduced with permission from Shatzkes DR, Haller JO, Velcek FT: Imaging of uterovaginal anomalies in the pediatric patient, Urol Radiol 1991;13(1):58-66.)


Obstentrics_Williams

Obstentrics_Williams. FIGURE 3-1 A. Cross-section of an embryo at 4 to 6 weeks. B. Large ameboid primordial germ cells migrate (arrows) from the yolk sac to the area of germinal epithelium, within the genital ridge. C. Migration of sympathetic cells from the spinal ganglia to a region above the developing kidney. Remnant of mesonephric duct Bladder-Urethra/ F Ureter -...--Uterus ---Rectum proliferation at the upper portion, a thick wedge of tissue cre ates the characteristic piriform uterine shape. At the same time, dissolution of cells at the lower pole forms the irst uterine cav ity (Fig. 3-2F). As the upper wedge-shaped septum is slowly reabsorbed, the inal uterine cavity is usually formed by the 20th week. If the two mullerian ducts fail to fuse, then two separate uterine horns remain. In contrast, resorption failure of the common tissue between them results in various degrees of persistent uterine septum.


Obstentrics_Williams

Obstentrics_Williams. As the distal end of the fused mullerian ducts contacts the uro genital sinus, this induces endodermal outgrowths from the sinus termed the sinovaginal bulbs. hese bulbs proliferate and fuse to form the vaginal plate, which later resorbs to form the vaginal lumen. his vaginal canalization is generally completed by the 20th week. However, the lumen remains separated from the urogenital sinus by the hymeneal membrane. This membrane further degenerates to leave only the hymeneal ring.


Obstentrics_Williams

Obstentrics_Williams. The close association of the mesonephric (wolian) and paramesonephric (mullerian) ducts explains the simultaneous abnormalities in their end organs. Kenney and colleagues (1i984) showed that up to half of females with urerovaginal malformations have associated urinary tract defects. Anomalies most frequently associated with renal defects are unicornuate uterus, uterine didelphys, and agenesis syndromes, whereas arcuate and bicornuate are less commonly linked (Reichman, 2010). When mullerian anomalies are identiied, the urinary system can be evaluated with magnetic resonance (MR) imaging, sonography, or intravenous pyelography (Hall-Craggs, 2013). With mullerian anomalies, ovaries are functionally normal but have a higher incidence of anatomical maldescent into the pelvis (Allen, 2012; Dabirashrafi, 1994).


Obstentrics_Williams

Obstentrics_Williams. As discussed, the mesonephric ducts usually degenerate, however, persistent remnants may become clinically apparent. Mesonephric or wolian vestiges can persist as Gartner duct cysts. These are typically located in the proximal anterolateral vaginal wall but may be found at other sites along the vaginal length. They can be further characterized by MR imaging, which provides excellent image resolution at soft tissue interfaces. Most cysts are asymptomatic and benign and usually do not require surgical excision. Intraabdominal wolian remnants in the female include a few blind tubules in the mesovarium-the epoophoronand similar ones adjacent to the uterus-paroophoron (see Fig. 3-2F) (Moore, 2013). The epoophoron or paroophoron may develop into clinically identiiable cysts in the adult. • Embryology of the Gonads


Obstentrics_Williams

Obstentrics_Williams. • Embryology of the Gonads At approximately 4 weeks, gonads derive from coelomic epithelium covering the medial and ventral surface of the nephrogenic cord at a site between the eighth thoracic and fourth lumbar segments. Because of this separate gonadal and mullerian derivation, women with mullerian defects typically have functionally normal ovaries and are phenotypic females. he coelomic epithelium thickens to form the genital ridge, also known as the gonadal ridge. Strands of these epithelial cells extend into the underlying mesenchyme as the primary sex cords. By the sixth week, primordial germ cells have migrated from the yolk sac to enter the genital ridge mesenchyme (Fig. 3-3). The primordial germ cells are then incorporated into the primary sex cords.


Obstentrics_Williams

Obstentrics_Williams. In the seventh week, the sexes can be distinguished, and tes tes are recognized during microscopic sectioning by their well deined radiating testis cords. These cords are separated from the coelomic epithelium by mesenchyme that is to become the tunica albuginea. The testis cords develop into the seminiferous tubules and rete testis. he rete testis establishes connection with small tubes arising of the mesonephric duct. These small tubes become the eferent ducts that drain into the epididymis and then into the vas deferens, which are main mesonephric duct derivatives.


Obstentrics_Williams

Obstentrics_Williams. In the female embryo, the primary sex cords give rise to the medullary cords, which persist only for a short time. The coelomic epithelium again proliferates into the underlying mesenchyme, and these strands are the cortical cords. By the fourth month, the cortical cords begin to form isolated cell clusters called primordial follicles. These follicles contain the oogonia, which derive from primordial germ cells and are surrounded by a single layer of lattened follicular cells derived from the cortical cords. Follicular cells serve as supporting nutrient cells. By 8 months, the ovary has become a long, narrow, lobulated structure that is attached to the body wall by the mesovarium. The coelomic epithelium has been separated by a band of connective tissue-tunica albuginea-from the cortex. At this stage, the cortex contains follicles and is well deined from the inner medulla, which is composed of abundant blood vessels, lymphatic vessels, and nerve ibers.


Obstentrics_Williams

Obstentrics_Williams. • Embryology of the External Genitalia Early development of the external genitalia is similar in both sexes. By 6 weeks' gestation, three external protuberances have developed surrounding the cloacal membrane. These are the left and right cloacal folds, which meet ventrally to form the genital tubercle (Fig. 3-4). With division of the cloacal membrane into anal and urogenital membranes, the cloacal folds become the anal and urethral folds, respectively. Lateral to the urethral folds, genital swellings arise, and these become the labioscrotal folds. Between the urethral folds, the urogenital sinus extends onto the surface of the enlarging genital tubercle to form the urethral groove. By week 7, the urogenital membrane ruptures, exposing the cavity of the urogenital sinus to amnionic fluid.


Obstentrics_Williams

Obstentrics_Williams. The genital tubercle elongates to form the phallus in males and the clitoris in females. Still, it is not possible to visually diferentiate between male and female external genitalia until week 12. In the male fetus, dihydrotestosterone (DHT) forms locally by the 5-a reduction of testosterone. DHT prompts the anogenital distance to lengthen, the phallus to enlarge, and the labioscrotal folds to fuse and form the scrotum. In the female fetus, without DHT, the anogenital distance does not lengthen, and the labioscrotal and urethral folds do not fuse (Fig. 3-4C). The genital tubercle bends caudally to become the clitoris, and the urogenital sinus forms the vestibule of the vagina. The labioscrotal folds create the labia majora, whereas the urethral folds persist as the labia minora. Female external genital diferentiation is complete by 11 weeks, whereas male external genital diferentiation is complete by 14 weeks.


Obstentrics_Williams

Obstentrics_Williams. Degenerating paramesonephric duct Primordial germ cell Uterine tube -FIGURE 3-3 Embryonic gonad diferentiation. TDF Persistent paramesonephric duct Coelomic epithelium Degenerating medullary cords = testis-determining factor. Labioscrotal/ , FIGURE 3-4 Development ofthe external genitalia. A. Indifferent stage. B. Virilization ofexternal genitalia. C. Feminization. (Reproduced with permission from Bradshaw KD: Anatomical disorders. In Hoffman BL, Schorge JO, Bradshaw KD, et al (eds): Williams Gynecology, 3rd ed. New York, McGraw Hill Education, 201o6.) Defining gender incorporates genetic gender, gonadal gender, and phenotypic gender. Genetic gender-X or Y -is established at fertilization. However, for the irst 6 weeks, development of male and female embf) os is morphologically indistinguishable.


Obstentrics_Williams

Obstentrics_Williams. Gonadal gender is heralded by the diferentiation of the primordial gonad into a testis or an ovary. If a Y chromosome is present, the gonad begins developing into a testis. Testis development is directed by a protein called the testis-determiningactor (TDF), which modulates the transcription of several genes involved in gonadal diferentiation. TDF is encoded by the sexdetermining region (SR) gene, located on the short arm of the Y chromosome. But testis development is much more complex and requires other autosomal genes (Nistal, 2015a). he importance of the SRYgene is demonstrated in severl paradoxical conditions. First, 46,X phenotypic males can result from translocation of the Y chromosome fragment containing SRY to the X chromosome during meiosis of male germ cells Wu, 2014). Similarly, 46,Y individuals can appear phenotypically female if they carry a mutation in the SRYgene (Helszer, 2013).


Obstentrics_Williams

Obstentrics_Williams. Last, phenoypic gender begins at 8 weeks' gestation. Before this, urogenital tract development in both sexes is indistinguishable. Thereafter, diferentiation of the internal and external genitalia to the male phenotype is dependent on testicular function. In the absence of a testis, female diferentiation ensues irrespective of genetic gender (Table 3-1).


Obstentrics_Williams

Obstentrics_Williams. In males, the fetal testis secretes a protein called mullerianinhibiting substance (MIS), also called antimullerian hormone (AMH) . It acts locally as a paracrine factor to cause mullerian duct regression. Thus, it prevents the development of uterus, fallopian tube, and upper vagina. AMH is produced by the Sertoli cells of the seminiferous tubules. Importantly, these tubules appear in fetal gonads and secrete AMH before diferentiation of Leydig cells, which are the cellular site of testosterone synthesis. AMH is secreted as early as 7 weeks, and mullerian duct regression is completed by 9 to 10 weeks. Because AMH acts locally near its site of formation, if a testis were absent on one side, the mullerian duct on that side would persist, and the uterus and fallopian tube would develop on that side.


Obstentrics_Williams

Obstentrics_Williams. Apparently through stimulation initially by human chorionic gonadotropin (hCG), and later by fetal pituitary luteinizing hormone (LH), the fetal testes secrete testosterone. his hormone acts directly on the wolian duct to efect the development of the vas deferens, epididymis, and seminal vesicles. Testosterone also enters fetal blood and acts on the external genitalia anlage. In these tissues, testosterone is converted to 5a-DHT to cause virilization of the external genitalia. As evident from the prior discussion, abnormal sex development may involve the gonads, internal duct system, or external genitalia. Rates vary and approximate 1 in every 1000 to 4500 births (Murphy, 2011; Ocal, 2011). The nomenclature used to describe disorders of sex development (DSDs) has evolved. Current classiication of these disorders include: (1) sex chromosome DSDs, (2) 46,Y DSDs, and (3) 46,X DSDs (Table 3-2) (Hughes, 2006).


Obstentrics_Williams

Obstentrics_Williams. Other important terms describe the abnormal phenotypic findings that can be found. First, some disorders of sexual development are associated with abnormal, underdeveloped gonads, that is, gonadal dysgenesis. With this, if a testis is poorly formed, it is called a dysgenetic testis, and if an ovary is poorly formed, it is called a streak gona. In afected patients, the underdeveloped gonad ultimately fails, which is indicated by elevated gonadotropin levels. Another important clinical sequela is that patients bearing a Y chromosome are at high risk of developing a germ cell tumor in the dysgenetic gonad. A second term, ambiguous genitalia, describes genitalia that do not appear clearly male or female. Abnormalities may include TABLE 3-1. Embryonic Urogenital Structures and Their Adult Homologues Uteroovarian and round ligaments Epoophoron, paroophoron Gartner duct Uterus, fallopian tubes, upper vagina Bladder, urethra Seminiferous tubules, Sertoli cells Gubernaculum testis


Obstentrics_Williams

Obstentrics_Williams. Uteroovarian and round ligaments Epoophoron, paroophoron Gartner duct Uterus, fallopian tubes, upper vagina Bladder, urethra Seminiferous tubules, Sertoli cells Gubernaculum testis Efferent ductules, paradidymis Epididymis, ductus deferens, Prostatic utricle, appendix of testis Bladder, urethra Floor of penile urethra TABLE 3-2. Disorders of Sex Development (DSD) Classification 45,X Turnerd 47,xXY Klinefelterd 45,X/46,XY Mixed gonadal dysgenesis 46,XX/46,XY Ovotesticular DSD 46,XY DSD 46,XX DSD aAnd syndrome variants. AMH = antimullerian hormone; hCG = human chorionic gonadotropin; LH = luteinizing hormone. Adapted with permission from Hughes lA, Houk C, Ahmed SF, et al: Consensus statement on management of intersex disorders. j Pediatr Urol 2:148,l2006. hypospadias, undescended testes, micropenis or enlarged clitoris, labial fusion, and labial mass.


Obstentrics_Williams

Obstentrics_Williams. hypospadias, undescended testes, micropenis or enlarged clitoris, labial fusion, and labial mass. Last, ovotesticular deines states characterized by ovarian and testicular tissue in the same individual. It was formerly termed true hermaphroditism. In these cases, diferent types of gonads can be paired. he types of gonads that may be paired include a normal testis, a normal ovary, a streak gonad, dysgenetic testis, or an ovotestis. In the latter, both ovarian and testicular elements are combined within the same gonad. With ovotesticular DSDs, the internal ductal system structure depends on the ipsilateral gonad and its degree of determination. Speciically, the amount of AMH and testosterone determines the degree to which the internal ductal system is masculinized or feminized. Extenal genitalia are usually ambiguous and undermasculinized due to inadequate testosterone. • Sex Chromosome Disorders of Sex


Obstentrics_Williams

Obstentrics_Williams. • Sex Chromosome Disorders of Sex Sex chromosome disorders of sexual development typically arise from an abnormal number of sex chromosomes. Of these, Turner and linefelter syndromes are most frequently encoun tered (Nielsen, 1990). Turner syndrome is caused by de novo loss or severe struc tural abnormality of one X chromosome in a phenotypic female. Most afected fetuses are spontaneously aborted. How ever, in girls with Turner syndrome who survive, phenotype varies widely, bur nearly all afected patients have short stat ure. Associated problems include cardiac anomalies (especially coarctation of the aorta), renal anomalies, hearing impairment, otitis media and mastoiditis, and an increased incidence of hypertension, achlorhydria, diabetes mellirus, and Hashimoto thyroiditis. It is the most common form of gonadal dysgenesis that leads to primary ovarian failure. In these cases, the uterus and vagina are normal and capable of responding to exogenous hormones (Matthews, 2017).


Obstentrics_Williams

Obstentrics_Williams. Another sex chromosome disorder is Klineelter syndrome (47,Y). hese individuals tend to be tall, undervirilized males with gynecomastia and small, firm testes. They have sig nificantly reduced fertility from hypogonadism due to gradual testicular cell failure. These men are at increased risk for germ cell rumors, osteoporosis, hypothyroidism, diabetes mellirus, breast cancer, cardiovascular abnormalities, and cognitive and psychosocial problems (Aksglaede, 2013; Calogero, 2017). Several karyotypes can create a coexistent ovary and testis, and thus ovotesticular DSD is found in all three DSD categories (see Table 3-2). In the sex chromosome group, ovotesticular DSD may arise from a 46,XX/46,XY karyotype. Here, an ovary, testis, or ovotestis may be paired. he phenotype in general mirrors that for ovotesticular disorders, which are described earlier on this page.


Obstentrics_Williams

Obstentrics_Williams. For others in the sex chromosome DSD group, ovotesticular disorder arises from a chromosomal mosaic such as 45,Xl46,XY. With this karyotype, a picture ofmixed gonadal dysgenesis shows a streak gonad on one side and a dysgenetic or normal testis on the other. The phenotypical appearance ranges from undervirilized male to ambiguous genitalia to Turner stigmata. • 46,XY Disorders of Sex Development Insuicient androgen exposure of a ferus destined to be a male leads to 46,XY DSD-formerly called male pseudohermaphroditism. he karyotype is 46,XY and testes are frequently present. he uterus is generally absent as a result of normal embryonic AMH production by Sertoli cells. hese subjects are most often sterile from abnormal spermatogenesis and have a small phallus that is inadequate for sexual function. As seen in Table 3-2, etiology of 46,XY DSD may stem from abnormal testis development or from abnormal androgen production or action.


Obstentrics_Williams

Obstentrics_Williams. 46,XY Gonadal Dysgenesis his spectrum of abnormal gonad underdevelopment includes pure or complete, partial, or mixed 46,XY gonadal dysgenesis. These are deined by the amount of normal testicular tissue and by karyotype. Because of the potential for germ cell rumors in dysgeneric testes and intraabdominal testes, afected patients routinely have been advised to undergo gonadectomy Giang, 2016). Of these, pure gonadal dysgenesis results from a mutation in the SRY gene or in other genes with testis-determining efects (Hutson, 2014). his leads to underdeveloped dysgenetic gonads that fail to produce androgens or AMH. Formerly named Swyer syndrome, the condition creates a normal prepubertal female phenotype and a normal miillerian system due to absentiAMH.


Obstentrics_Williams

Obstentrics_Williams. Partial gonaal dysgenesis deines those with gonad development intermediate between normal and dysgenetic testes. Depending on the percentage of underdeveloped testis, wolian and miille rian structures and genital ambiguity are variably expressed. Mixed gonadal dysgenesis is one type of ovotesticular disorder of sexual diferentiation. As discussed on page 39, one gonad is streak, and the other is a normal or a dysgenetic testis. Of afected individuals, 15 percent have a 46,Y karyotype (Nistal, 20 15 b). The phenotype is wide ranging as with partial gonadal dysgenesis. Last, testicular regression can follow initial testis development. A broad phenotypic spectrum is possible and depends on the timing of testis failure.


Obstentrics_Williams

Obstentrics_Williams. Last, testicular regression can follow initial testis development. A broad phenotypic spectrum is possible and depends on the timing of testis failure. In some cases, 46,Y disorders of sexual diferentiation stem from abnormalities in: (1) testosterone biosynthesis, (2) LH receptor function, (3) AMH function, or (4) androgen receptor action. First, the sex steroid biosynthesis pathway can sufer enzymatic defects that block testosterone production. Depending on the timing and degree of blockade, undervirilized males or phenotypic females may result. In contrast to these central enzymatic defects, peripheral defects may be causative. Namely, abnormal 5-. reductase type 2 enzyme action leads to impaired conversion of testosterone to DHT and thus to undervirilization.


Obstentrics_Williams

Obstentrics_Williams. Second, hCG/LH receptor abnormalities within the testes can lead to Leydig cell aplasia/hypoplasia and impaired testosterone production. In contrast, disorders of MH and AMH receptors result in persistent miillerian duct syndrome (PMDS). Afected patients appear as males but have a persistent uterus and fallopian tubes due to failed AMH action. Last, the androgen receptor may be defective and result in androgen-insensitivity syndrome (AIS). Resistance to androgens may be incomplete and associated with varying degrees of virilization and genital ambiguity. Milder forms have been described in men with severe male factor infertility and poor virilization.


Obstentrics_Williams

Obstentrics_Williams. Females with complete androgen-insensitivity syndrome (CAIS) appear as phenotypically normal females at birth. They often present at puberty with primary amenorrhea. External genitalia appear normal; scant or absent pubic and axillary hair are noted; the vagina is shortened or blind ending; and the uterus and fallopian tubes are absent. However, these individuals develop breasts during pubertal maturation due to abundant androgen to estrogen conversion. Testes may be palpable in the labia or inguinal area or may be found intraabdominally. Surgical excision of the testes after puberty is recommended to decrease the associated risk of germ cell tumors, which may be as high as 20 to 30 percent. • 46,XX Disorders of Sex Development As seen in Table 3-2, etiology of 46,X disorders of sexual differentiation may stem from abnormal ovarian development or from excess androgen exposure.


Obstentrics_Williams

Obstentrics_Williams. • 46,XX Disorders of Sex Development As seen in Table 3-2, etiology of 46,X disorders of sexual differentiation may stem from abnormal ovarian development or from excess androgen exposure. Disorders of ovarian development of those with a 46,X complement include: (1) gonadal dysgenesis, (2) testicular DSD, and (3) ovotesticular DSD. With 4, X gonadal dysgenesis, similar to Turner syndrome, streak gonads develop. These lead to hypogonadism, prepubertal normal female genitalia, and normal miillerian structures, but other Turner stigmata are absent.


Obstentrics_Williams

Obstentrics_Williams. With 4,X testicuar DSD, several possible genetic mutations lead to testis-like formation within the ovary-streak gonad, dysgenetic testis, or ovotestis. Defects may stem from SRY translocation onto one X chromosome. In individuals without SRY translocation, other genes with testis-determining efects are most likely activated. Regardless, production of MH prompts miillerian system regression, and androgens promote wolian system development and external genitalia masculinization. Spermatogenesis, however, is absent due to a lack of needed genes on the long arm of the Y chromosome. hese individuals are not usually diagnosed until puberty or during infertility evaluation. With 4,X ovotesticular DSD, individuals possess a unilateral ovotestis with a contralateral ovary or testis, or bilateral ovotestes. Phenotypic indings depend on the degree of androgen exposures and mirror those for other ovotesticular DSDs discussed on page 39.


Obstentrics_Williams

Obstentrics_Williams. Discordance between gonadal sex (46,X) and the phenotypic appearance of external genitalia (masculinized) may also result from excessive fetal androgen exposure. his was previously termed female pseudohermaphroditism. In afected individuals, the ovaries and female internal ductal structures such as the uterus, cervix, and upper vagina are present. hus, patients are potentially fertile. he external genitalia, however, are virilized to a varying degree depending on the amount and timing of androgen exposure. he three embryonic structures that are commonly afected by elevated androgen levels or ovarian development disorders are the clitoris, labioscrotal folds, and urogenital sinus. As a result, virilization may range from modest clitoromegaly to posterior labial fusion and development of a phallus with a penile urethra. Degrees of virilization can be described by the Prader score, which ranges from 0 for a normal-appearing female to 5 for a normal, virilized male.


Obstentrics_Williams

Obstentrics_Williams. Fetal, placental, or maternal sources can provide the excessive androgen levels. Maternally derived androgen excess may come from virilizing ovarian tumors such as luteoma and Sertoli-Leydig cell tumor or from virilizing adrenal tumors. Fortunately, these neoplasms infrequently cause fetal efects because of the tremendous ability of placental syncytiotrophoblast to convert C19 steroids-androstenedione and testosterone-to estradiol via the enzyme aromatase (Chap. 5, p. 103). As another source, drugs such as testosterone, danazol, and other androgen derivatives may cause fetal virilization. Of fetal sources, exposure can arise from fetal congenital adrenal hyperplasia (CAH). his stems from a fetal enzyme dei ciency in the steroidogenic pathway that leads to androgen accu mulation. The most common defect is 21-hydroxylase deiciency. CAH is a frequent cause of virilization and has an incidence approximating 1 in 10,000 to 20,000 live births (Speiser, 2010).


Obstentrics_Williams

Obstentrics_Williams. With CAH, phenotypes depend on the location of the enzyme defect in the steroidogenic pathway and on the severity of the resulting enzymatic deiciency (Miller, 201i1). With severe enzymatic deiciency, afected newborns have life-threatening salt wasting and virilization. Other mutations may prompt virilization alone (Auchus, 2015). he mildest abnormalities present later and are described as "nonclassic," "late-onset," or "adult-onset" CAH. In these patients, activation of the adrenal axis at puberty increases steroidogenesis and unmasks a mild enzymatic deficiency. Excess androgen provides negative feedback to gonadotropin-releasing hormone (GnRH) receptors in the hypothalamus. These patients oten present with hirsutism, acne, and anovulation. Thus, lateonset CAH may mimic polycystic ovarian syndrome (McCannCrosby, 2014). In some instances, CAH can be diagnosed antenatally. Early maternal dexamethasone therapy can dampen androgen excess to minimize virilization (Chap. 16, p. 317).


Obstentrics_Williams

Obstentrics_Williams. Of rare placental sources, placental aromatase deiciency from a fetal CP 19 gene mutation causes an accumulation of placental androgen and underproduction of placental estrogens (Chap. 5, p. 105) Gones, 2007). Consequently, both the mother and the 46,X fetus are virilized. Delivery of a newborn with a disorder of sexual diferentiation is a potential medical emergency and can create possible longlasting psychosexual and social ramiications for the individual and family. Ideally, as soon as the afected neonate is stable, parents are encouraged to hold the child. he newborn is referred to as "your baby," and suggested terms include "phallus," "gonads," "folds," and "urogenital sinus" to reference underdeveloped structures. The obstetrician explains that the genitalia are incompletely formed and emphasizes the seriousness of the situation and the need for rapid consultation and laboratory testing.


Obstentrics_Williams

Obstentrics_Williams. Because similar or identical phenotypes may have several etiologies, identiication of a speciic DSD may require several diagnostic tools (McCann-Crosby, 2015). Relevant neonatal physicl examination evaluates: (1) ability to palpate gonads in the labioscrotal or inguinal regions, (2) ability to palpate uterus during rectl examination, (3) phallus size, (4) genitalia pigmentation, and (5) presence of other syndromic features. The newborn metabolic condition is assessed, as hyperkalemia, hyponatremia, and hypoglycemia may indicate CAH. he mother is examined for signs of hyperandrogenism. Other neonatal tests include genetic studies, hormone measurements, imaging, and in some cases endoscopic, laparoscopic, and gonadal biopsy. Sonography shows the presence or absence of miillerian/wolian structures, n locate the gonads, and can identiy associated mlformations such as renal anomalies.


Obstentrics_Williams

Obstentrics_Williams. Very early during embryo formation, a bilaminar cloacal membrane lies at the caudal end of the germinal disc and forms the infraumbilical abdominal wall. Normally, an ingrowth of mesoderm between the ectodermal and endodermal layers of the cloacal membrane leads to formation of the lower abdomi nal musculature and pelvic bones. Without this reinforcement, the cloacal membrane may prematurely rupture, and depend ing on the extent of the infraumbilical defect, cloacal exstrophy, bladder exstrophy, or epispadias may result. Of these, cloacal exstrophy is rare. It includes the triad of omphalocele, bladder exstrophy, and imperforate anus.


Obstentrics_Williams

Obstentrics_Williams. Of these, cloacal exstrophy is rare. It includes the triad of omphalocele, bladder exstrophy, and imperforate anus. Bladder exstrophy is uncommon and is characterized by an exposed bladder lying outside the abdomen. Associated ind symphysis pubis. At the same time, however, the uterus, fal lopian tubes, and ovaries are typically normal except for occa sional miillerian duct fusion defects. Pregnancy with bladder exstrophy is associated with greater risk for antepartum pyelonephritis, urinary retention, ureteral obstruction, pelvic organ prolapse, preterm birth, and breech presentation. The guidelines for pregnancy (Eswara, 2016). Due to the exten encountered, some recommend planned cesarean delivery at a tertiary center (Deans, 2012; Dy, 2015; Greenwell, 2003). Epispadias without bladder exstrophy is rare and develops in association with other anomalies such as a widened, patulous tened mons pubis. Vertebral abnormalities and pubic symphy sis diathesis are also common .


Obstentrics_Williams

Obstentrics_Williams. Clitoral anomalies are unusual. One is clitoral duplication or biid clitoris, which is rare and usually develops in association with bladder exstrophy or epispadias. With female phallic urethra, the urethra opens at the clitoral tip. Last, clitoromegaly noted at birth suggests fetal exposure to excessive androgens (p. 40). In other cases, congenital clitoromegaly in females born extremely premature is a rare but well-recognized finding thought to be due to transient androgen levels in these neonates (Greaves, 2008).


Obstentrics_Williams

Obstentrics_Williams. As noted, the hymen marks the embryological boundary between structures derived from the miillerian and urogenital sinus. Hymeneal anomalies include imperforate, microperforate, cribriform (sievelike), navicular (boat-shaped), and septate hymens. They result from failure of the inferior end of the vaginal plate-the hymeneal membrane-to canalize. Their incidences approximate 1 in 1000 to 2000 females (American College of Obstetricians and Gynecologists, 2016). During the neonatal period, signiicant amounts of mucus can be secreted due to maternal estrogen stimulation. With an imperforate hymen, secretions collect to form a bulging, translucent yellow-gray mass, termed hydro-or mucocolpos, at the vaginal introitus. Most are asymptomatic and resolve as mucus is reabsorbed and estrogen levels decrease, but rarely can cause perinatal urinary retention from their mass efects Gohal, 2009).


Obstentrics_Williams

Obstentrics_Williams. Four principal deformities arise from defective miillerian duct embryological steps: (1) agenesis of both ducts, either focally or along the entire duct length; (2) unilateral maturation of one mullerian duct with incomplete or absent development of the opposite side; (3) absent or faulty midline fusion of the ducts; or (4) defective canalization. Various classifications have been proposed, and Table 3-3 shows the one from the American Fertility Society (1988). It separates anomalies into groups with similar clinical characteristics, prognosis for pregnancy, and treatment. It also includes one for abnormalities associated with fetal exposure to diethylstilbestrol (DES). Several other classiication systems have been crafted, but this one is the most widely used (Acien, 2011; Di Spiezio Sardo, 2015; Oppelt, 2005).


Obstentrics_Williams

Obstentrics_Williams. Mullerian anomalies may be suspected by symptoms or physical findings such as vaginal septa, blind-ending vagina, or duplicated cevix. Amenorrhea may be an initial complaint for those with agenesis of a mullerian component. In those with outlet obstruction, pelvic pain from occult blood that accumulates and distends the vagina, uterus, or fallopian tubes may arise from functioning endometrium. Endometriosis and its associated dysmenorrhea, dyspareunia, and chronic pain are also frequent with outlet obstruction. Class I segmental defects are caused by mullerian hypoplasia or agenesis as shown in Figure 3-5. These developmental defects can afect the vagina, cervix, uterus, or fallopian tubes and may be isolated or may coexist with other mullerian defects. TABLE 3-3. Classification of MU"erian Anomalies I. Segmental mullerian hypoplasia or agenesis ab. Vaginal . Cervical c. d. e. II. Unicornuate uterus a. b. c. d. III. Uterine didelphys IV. Bicornuate uterus a.


Obstentrics_Williams

Obstentrics_Williams. I. Segmental mullerian hypoplasia or agenesis ab. Vaginal . Cervical c. d. e. II. Unicornuate uterus a. b. c. d. III. Uterine didelphys IV. Bicornuate uterus a. Complete-division to internal os b. V. Septate uterus a. Complete-septum to internal os b. VI. Arcuate VII. Diethylstilbestrol related Data from American Fertility Society: The American Fertility Society classifications of adnexal adhesions, distal tubal occlUSion, tubal occlusion secondary to tubal ligation, tubal pregnancies, Mullerian anomalies and intrauterine adhesions, Fertil Steril 1988 Jun;49(6):944-955.


Obstentrics_Williams

Obstentrics_Williams. Of all vaginal anomalies, vaginal agenesis is the most profound and may be isolated or associated with other mullerian anomalies. One example is the Mayer-Rokitansky-Kuster-Hauser (MRKH) syndrome, in which upper vaginal agenesis is typically associated with uterine hypoplasia or agenesis. Less often, this syndrome also displays abnormalities of the renal, skeletal, and auditory systems. his triad is known by the acronym MURCS, which reflects mullerian duct aplasia, renal aplasia, and �ervicothoracic �omite dysplasia (Rall, 2015).


Obstentrics_Williams

Obstentrics_Williams. he obstetrical significance of vaginal anomalies depends greatly on the degree of obstruction. Complete vaginal agenesis, unless corrected operatively, precludes pregnancy by vaginal intercourse. With MRKH syndrome, a functional vagina can be created, but uterine agenesis proscribes childbearing. In these women, however, ova can be retrieved for in vitro fertilization (IVF) in a surrogate mother (F riedler, 2016). U terine transplantation is currently experimental but holds future promise for these women Qohannesson, 2016). Of other vaginal anomalies, congenital septa may form longitudinally or transversely, and each can arise from a fusion or resorption defect. Longitudinal septa divide the vagina into right and left portions. hey may be complete and extend the entire vaginal length. Partial septa usually form high in the vagina but may develop at lower levels. Septa are typically associated with other mullerian anomalies (Haddad, 1997).


Obstentrics_Williams

Obstentrics_Williams. During labor, a complete longitudinal vaginal septum usually does not cause dystocia because the vaginal side through which the fetus descends dilates satisfactorily. An incomplete or partially obstructed longitudinal septum, however, may interfere with descent. Occasionally, a woman with a distal longitudinal septum presents in labor. During second-stage labor, this septum usually becomes attenuated by pressure from the fetal head. After ensuring adequate analgesia, the inferior attachment of the septum is isolated, clamped, transected, and ligated. Following placenta delivery, the superior attachment can be transected while carefully avoiding urethral injury.


Obstentrics_Williams

Obstentrics_Williams. A transverse septum poses an obstruction of variable thickness. It may develop at any depth within the vagina, but most are in the lower third (Williams, 2014). These mayior may not be perforate, and thus obstruction or infertility is variably present. In labor, perforate strictures may be mistaken for the upper limit of the vaginal vault, and the septal opening is misidentiied as an undilated cervical os (Kumar, 2014). If encountered during labor, and ater the external os has dilated completely, the head impinges on the septum and causes it to bulge downward. If the septum does not yield, slight stretching pressure on its opening usually leads to further dilatation, but occasionally cruciate incisions are required to permit delivery (Blanton, 2003). If there is a thick transverse septum, however, cesarean delivery may be necessary. Developmental abnormalities of the cervix include partial or complete agenesis, duplication, and longitudinal septa.


Obstentrics_Williams

Obstentrics_Williams. Developmental abnormalities of the cervix include partial or complete agenesis, duplication, and longitudinal septa. I. Hypoplasia/agenesis II. Unicornuate A. Vaginal B. Cervical A. Communicating B. Noncommunicating C. Fundal D. Tubal E. Combined C. No cavity D. No horn III. Didelphys IV. Bicornuate A. Complete B. Partial V. Septate VI. Arcuate VII. DES related A. Complete B. Partial FIGURE 3-5 Classification of mOllerian anomalies. DES = diethylstilbestrol.(Modified with permission from American Fertility Society: The American Fertility Society classifications of adnexal adhesions, distal tubal occlusion,tubalocclusion secondary to tubal ligation, tubal pregnancies, MOlierian anomalies and intrauterine adhesions, Ferril Steril 1988 Jun;49(6):944-55.l


Obstentrics_Williams

Obstentrics_Williams. Uncorrected complete agenesis is incompatible with pregnancy, and in vitro ferrilization with gestational surrogacy is an option. Surgical correction by uterovaginal anastomosis has resulted in successful pregnancy (Kriplani, 201e2). Significant complications accompany this correcrive surgery, and rhe need for clear preoperative anatomy delineation has been emphasized by Rock (2010) and Roberrs (2011) and their colleagues. For this reason, they recommend hysterecromy for complete cervi� cal agenesis and reserve reconsrruction attemprs for carefully selected patients with cervical dysgenesis.


Obstentrics_Williams

Obstentrics_Williams. From a large variery, a few of the more common congenital urerine malformations are shown in Table 3-3. An accurate population prevalence of these is diicult to assess because the best diagnostiC techniques are invasive. That said, the prevalence found with imaging ranges from 0.4 to 10 percent, and rates in women with recurrent miscarriage are signiicantly higher (Byrne. 2000; Dreisler. 2014; Saravclos. 2008). In a general population, the mOSt common inding is arcuare urerus, followed in descending order by septate, bicornuate, didelphic, and unicornuate classes (Chan, 2011b).


Obstentrics_Williams

Obstentrics_Williams. ination, cesarean delivery, rubal sterilization, or infertility evaluation. Depending on clinical presenrarion, diagnostic tools may include sonography, hysterosalpingography, magnetic� resonance imaging, laparoscopy, and hysteroscopy. Each has limitations, and rhese may be used in combination ro completely deine anatomy. In women undergoing fertiliry evaluation, hysterosalpingography (HSG) is commonly selected for uterine cavity and tubal patency assessment. It is contraindi� cared during pregnancy. HSG poorly deines the external urerine contour and can delineate only patent cavities. Regarding patency, remember that some uniconuate rudimentary horns lack a caviry. Also, ourlet Obstructions will preclude dye illing.


Obstentrics_Williams

Obstentrics_Williams. In most clinical senings, rwo-dimensional transvaginal sonography (2-D VS) is initially performed. For this indication, the pooled accuracy for VS is 90 to 92 percent (Pellerito. 1992). Saline infusion sonography (SIS) improves delineation of the endome[fium and intenal merine morphology, bur only with a patent endometrial cavity. It also is contraindicated in pregnancy. Three-dimensional (3-D) sonography is more accurate than 2·D sonography because it provides uterine images from virtually any angle. Thus, coronal images can be constructed as shown in Figure 3-6, and these are essential in evaluating borh


Obstentrics_Williams

Obstentrics_Williams. FIGURE 3-6 Three-dimensional transvaginal sonographic images. A. Bicornuate uterus with an 8-week gestation. The external fundal contour (red doted ine) dips centrally below the intercornual line, and the endometrial cavities communicate. B. Septate uterus with a S-week gestation. The external fundal contour is normal and convex 'elow dotted ine), and the long septum (asterisk) extends caudad in the midline. C. Arcuate uterus with an 8-week gestation. The external fundal contour is normal and convex (red dotted line), but the fundal endometrial cavity is slightly indented (arrow). internal and exrernaJ uterine contours (Grimbizis, 2016). Both 2-D and 3-D sonography arc suirable for use in pregnancy.


Obstentrics_Williams

Obstentrics_Williams. internal and exrernaJ uterine contours (Grimbizis, 2016). Both 2-D and 3-D sonography arc suirable for use in pregnancy. Several studies have reported very good concordance between 3-D TVS and MR imaging of muUerian anomalies (Deutch, 2008; Graupera, 2015). MR imaging is often preferred for complex anatomy, especially cases for which corrective surgery is planned. MR imaging provides clear delineation of both the internal and external uterine anatomy and has a reported accuracy of up to 100 percent for mullerian anomaly evaluation (Bermejo, 20 I0; Pellerito, 1992). In addition, com plex anomalies and commonly associatcd secondary diagnoses such as renal or skeletal anomalies can be concurrendy evaluated. Precautions wirh MR imaging in pregnancy are discussed in Chapter 46 (p. 910).


Obstentrics_Williams

Obstentrics_Williams. In some women undergoing an inferrility evaluation. hysteroscopy and laparoscopy may be selected co assess for mullerian anomalies; screen for endomctriosis, which is often coexistent; and exclude other tubal or uterine cavity pathologies (Puscheck, 2008; Saravelo" 2008). In pregnancy, these approaches are rarely used co diagnose mullerian anomalies. and hysteroscopy is contraindicated.


Obstentrics_Williams

Obstentrics_Williams. Wirh this abnormality, the underdeveloped or rudimentary horn may be absent. If present, it may or may nor communicatewith the domin�nr horn �nd may or may not contain an endomerrium-Iined cavity (see Fig. 3-5). General population estimates cite an incidence of I in 4000 women (Reichman, 2009). This anomaly may be detected during ferrility evaluation by HSG. Bur as nored, noncommunicating or noncavirary rudimentary horns may not ill with dye. If this anomaly is suspected. 3-D sonography increases diagnostic accuracy, but again MR imaging may be preferred. Importantly, 40 percent of afected women will have renal anomalies (Fedele, 1996).


Obstentrics_Williams

Obstentrics_Williams. This mullerian anomaly carries signiicant obstetrical risks, including first-and second-trimester miscarriage. malpresentation, fetal-growth restricrion. fetal demise. prematurely ruprured membranes, and preterm delivery (Chan, 2011 a; Hua, 2011; Reichman, 2009). Abnormal uterine blood Row, cervicl incompetence, and diminished cavity size and muscle mass of the hemiurerus are postulated ro underlie these risks (Donderwinkel, 1992).


Obstentrics_Williams

Obstentrics_Williams. Rudimentary horns also increase the risk for an ectopic pregnancy within rhe remnant, which may be disastrous. This risk includes noncommunicating cavitary rudiments, for which transperironeal sperm migration permirs ovum fertilization and pregnancy (Nahum, 2004). In a report of 70 sllch pregnancies, Rolen and associares (1966) found that the rudimentary uterine horn ruptured prior to 20 weeks in most. Nahum (2002) reviewed the literature from 1900 to 1999 and identiied 588 rudimentary horn pregnancies. Half had uterine rupture, and 80 percent did so before the third rrimesrer. Of the rotal 588, the neonatal survival race was only 6 percent. Imaging allows an earlier diagnOSiS of rudimentary horn pregnancy so that it can be treated either medically with methotrexare or surgically before rupture (Dove, 2017; Edelman, 2003; Khati, 2012; Worley, 2008). lthough not emphasized in Figure 3-5, the anachmem sire between rhe rudimentary horn at times can be broad and vascular.


Obstentrics_Williams

Obstentrics_Williams. If diagnosed in a nonpregnant woman, mOSt recommend prophylactic excision of a horn thac has a cavity (Fedele, 2005; Rackow, 2007). Data regarding subsequent pregnancy after excision are scarce. In one series of eight women, all had a preterm cesarean delivery (pados, 2014). This mullerian anomaly arises from a complere lack of fusion rhat results in twO enrirely separate hemiureri, cervices, and usually (yo vaginas (see Fig. 3-5). It is common among marsupials, for example, the American possum-Didelphys virginiana. Most women have a double vagina or a longitudinal vaginal septum. Urerine didelphys may be isolated. Or, it may compose a triad with an Qbstructed hemiyagina and with ipsilateral renal Igenesis (OHVlRA), also known as HerlynWerner-Wunderlich syndrome (Tong, 2013).


Obstentrics_Williams

Obstentrics_Williams. These anomalies are suspected on pelvic examinarion by identificarion of a longitudinal vaginal septum and two cervices. During HSG for fertility evaluation, contrast shows twO separate endocervical canals. These open into separare noncommunicating fusiform endometrial cavities char each ends wirh a solitary fallopian tube. In women without fertility issues, 2-or 3-D TVS is a logical initial imaging tool, and separate diver gent uterine horns with a large intervening fundal cleft are seen. Endometrial cavities are uniformly separate. MR imaging may be valuable in cases without classic indings. Adverse obstetrical outcomes associated with uterine didel phys are similar but less frequent than those seen with unicornu ate uterus. Increased risks include miscarriage, pre term birth, and malpresentation (Chan, 2011a; Grimbizis, 2001; Hua, 2011).


Obstentrics_Williams

Obstentrics_Williams. Metroplasty for either uterine didelphys or bicornuate uterus involves resection of intervening myometrium and fundal recombination (Alborzi, 2015). hese rarely performed surgeries are chosen for highly selected patients with otherwise unexplained miscarriages. Moreover, no evidence-based data conirm the eicacy of such surgical repair. his fusion anomaly results in two hemiuteri. As shown in Figure 3-5, the central myometrium runs either partially or completely to the cervix. A complete bicornuate uterus may extend to the internal cervical os and have a single cervix (bicornuate unicollis) or reach the external os (bicornuate bicollis). As with uterine didelphys, a coexistent longitudinal vaginal septum is not uncommon.


Obstentrics_Williams

Obstentrics_Williams. Radiological discrimination of a bicornuate uterus from a septate uterus can be challenging. This distinction, however, is important because septate uterus can be treated with hysteroscopic septal resection. HSG or 2-D TVS may initially suggest an anomaly, but further distinction is provided by 3-D TVS or MR imaging (see Fig. 3-6). With these, an intercornual angle greater than 105 degrees typiies a bicornuate uterus, whereas one less than 75 degrees indicates a septate uterus. Fundal contour also assists, and a straight line drawn between the imaged tubal ostia serves as the defining threshold. Referent to this, an intrafundal downward cleft measuring �1 em or more is indicative of bicornuate uterus. A septate uterus shows a cleft depth < 1 em, or it may have a normal fundal contour.


Obstentrics_Williams

Obstentrics_Williams. Bicornuate uterus carries increased risks for adverse obstetrical outcomes that include miscarriage, preterm birth, and malpresentation. As discussed in the prior section, rare surgical correction by metroplasty is reserved for highly selected patients. With this anomaly, a resorption defect leads to a persistent complete or partial longitudinal uterine septum (see Fig. 3-5). Less often, a complete vaginocervicouterine septum is found (Ludwin, 2013). Many septate uteri are identiied during evaluation of infertility or recurrent pregnancy loss. Although an abnormality may be identiied with HSG or 2-D TVS, typically 3-D TVS or MR imaging is required to diferentiate this from a bicornuate uterus (see Fig. 3-6).