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Obstentrics_Williams. There may be a lower-threshold dose of 0.3 Gy (30 rad), which is a range similar to the window of cortical sensitivity in the mouse model discussed earlier. he mean decrease in intelligence quo tient (IQ) scores was 25 points per Gy or 100 rad. here appears to be linear dose response, but it is not clear whether there is a threshold dose. Most estimates err on the conservative side by assuming a linear nonthreshold hypothesis. In a study of fetuses exposed to low radiation doses, Choi and colleagues (2012) did not find an increased risk for congenital anomalies. Finally, an increased risk of mental retardation in humans < 8 weeks' or > 25 weeks' gestation has not been documented, even with doses exceeding 0.5 Gy or 50 rad (International


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Obstentrics_Williams. Finally, an increased risk of mental retardation in humans < 8 weeks' or > 25 weeks' gestation has not been documented, even with doses exceeding 0.5 Gy or 50 rad (International Commission on Radiological Protection, 2003). Reports have described high-dose radiation used to treat women for malig nancy, menorrhagia, and uterine myomas. Dekaban (1r968) described 22 infants with microcephaly, mental retardation, or both following exposure in the first half of pregnancy to an estimated 2.5 Gy or 250 rad. Summary of Fetal Radiation Exposure From 8 to 15 weeks, the fetus is most susceptible to radiation induced mental retardation. It has not been resolved whether this is a threshold or nonthreshold linear function of dose. he


Obstentrics_Williams

Obstentrics_Williams. From 8 to 15 weeks, the fetus is most susceptible to radiation induced mental retardation. It has not been resolved whether this is a threshold or nonthreshold linear function of dose. he Committee on Biological Efects (1990) estimates the risk of severe mental retardation to be as low as 4 percent for 0.1 Gy (10 rad) and as high as 60 percent for 1.5 Gy (150 rad). But recall that these doses are 2 to 100 times higher than those considered maximal from diagnostic radiation. Importantly, cumulative doses from multiple procedures may reach the harmful range, especially at 8 to 15 weeks' gestation. At 16 to 25 weeks, the risk is less. And again, there is no proven risk before 8 weeks or after 25 weeks.


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Obstentrics_Williams. Importantly, embryofetal risks from low-dose diagnostic radiation appear to be minimal. Current evidence suggests that risks for malformations, growth restriction, or abortion are not increased from a radiation dose of less than 0.05 Gy (5 rad). Indeed, Brent (2009) concluded that gross congenital malformations would not be increased with exposure to less than 0.2 Gy (20 rad). Because diagnostic x-rays seldom exceed 0.1 Gy (10 rad) , Strzelczyk and associates (2007) concluded that these procedures are unlikely to cause deterministic efects. As emphasized by Groen and coworkers (2012), 0.1 Gy is the radiation equivalent to that from more than 1000 chest x-rays!


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Obstentrics_Williams. These efects refer to random, presumably unpredictable oncogenic or mutagenic efects of radiation exposure. Stochastic efects concern associations between fetal diagnostic radiation exposure and increased risk of childhood cancers or genetic diseases. According to Doll and Wakeford (1997), as well as the National Research Council (2006) BEIR VII Phase 2 report, excess cancers can result from in utero exposure to doses as low as 0.01 Svror 1 rad. Stated another way by Hurwitz and colleagues (2006), the estimated risk of childhood cancer following fetal exposure to 0.03 Gy or 3 rad doubles the background risk of 1 in 600 to that of 2 in 600.


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Obstentrics_Williams. In one report, in utero radiation exposure was determined for 10 solid cancers in adults from age 17 to 45 years. here was a dose-response relationship as previously noted at the 0.r1 Sv or 10 rem threshold. hese cancers likely are associated with a complex series of interactions between DNA and ionizing radiation. They also make it more problematic to predict cancer risk from low-dose radiation of less than 0.1 Sv or 10 rem. Importantly, below doses of 0.1 to 0.2 Sv, there is no convincing evidence of a carcinogenic efect (Brent, 2009, 2014; Preston, 2008; Strzelczyk, 2007).


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Obstentrics_Williams. Estimates of dose to the uterus and embryo for various frequently used radiographic examinations are summarized in Table 46-5. Imaging of maternal body parts farthest from the uterus results in a very small dose of radiation scatter to the embryo or fetus. The size of the woman, radiographic technique, and equipment performance are other variables (Wagner, 1997). hus, data in the table serve only as guidelines. When the radiation dose for a specific individual is required, a medical physicist should be consulted. Brent (2009) recommends consulting the Health Physics Society website (ww.hps.org) to view some examples of questions and answers posed by patients exposed to radiation.


Obstentrics_Williams

Obstentrics_Williams. he Radiation Therapy Committee Task Group of the American Association of Physics in Medicine (Stovall, 1995) emphasizes careful individualization of radiotherapy for the pregnant woman (Chap. 63, p. 1191). For example, in some cases, shielding of the fetus and other safeguards can be employed (Fenig, 2001; Nuyttens, 2002). In other instances, the fetus will be exposed to dangerous radiation doses, and a carefully designed plan must be improvised (Prado, 2000). Examples include models that estimate the fetal dose given during maternal brain radiotherapy or tangential breast irradiation (Mazonakis, 1999, 2003). The harmful efects of radiotherapy on future fertility and pregnancy outcomes were reviewed by Wo and Viswanathan (2009) and others and are detailed in Chapter 63 (p. 1192).


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Obstentrics_Williams. To estimate fetal risk, approximate x-ray dosimetry must be known. According to the merican College of Radiology, no single diagnostic procedure results in a radiation dose signiicant enough to threaten embryo-fetal well-being (Hall, 1991).


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Obstentrics_Williams. For standard radiographs, dosimetry is presented in Table 46-5. In pregnancy, the AP-view chest radiograph is the most commonly used study, and fetal exposure is exceptionally small-0.0007 Gy or 70 mrad. With one abdominal radiograph, because the embryo or fetus is directly in the x-ray beam, the dose is higher-O.OO 1 Gy or 100 mrad. he standard intravenous pyelogram may exceed 0.005 Gy or 500 mrad because of several exposures. The one-shot pyelogram described in Chapter 53 (p. 1030) is useful when urolithiasis or other causes of obstruction are unproven by sonography but still suspected. Most "trauma series," such as radiographs of an extremity, skull, or rib series, deliver low doses because of the fetal distance from the target area (Shakerian, 2015).


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Obstentrics_Williams. Dosimetry calculations are much more diicult with these procedures because of variations in the number of radiographs obtained, total fluoroscopy time, and luoroscopy time in which the fetus is in the radiation field. As shown in Table 46-6, the range is variable. he Food and Drug Administration (FDA) limits the exposure rate for conventional fluoroscopy such as barium studies, however, special-purpose systems such as angiography units have the potential for much higher exposure. Dosea per View Study View (mGy) No. Filmsb Dose (mGy) TABLE 6-5. Dose to the Uterus for Common Radiologic Procedures SkuW AP, PA, Lat <0.0001 Chest AP, PN, Latd <0.0001n-0.0008 <0.0005 1.5 0.0002-0.0007 Mammogramd Cc, Lat <0.0003-0.0005 4.0 0.0007 -0.002 Lumbosacral spinee AP, Lat 1.14-2.2 3.4 1.76-3.6 Abdomene AP 1.0 0.8-1n.63 Intravenous pyelograme 3 views 5.5 6.9-14 Hipb (single) AP 0.7-1.4 2.0 1-2


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Obstentrics_Williams. Hipb (single) AP 0.7-1.4 2.0 1-2 Lat 0.18-0.51 aCalculated for x-ray beams with half-value layers ranging from 2 to 4 mm aluminum equivalent using the methodology of Rosenstein, 1988. bBased on data and methods reported by Laws, 1978. (Entrance exposure data from Conway, 1989. dEstimates based on compilation of above data. eBased on NEXT data reported in National Council on Radiation Protection and Measurements, 1989. AP = anterior-posterior; CC = cranial-caudal; Lat = lateral; PA = posterior-anterior. TABLE 46-6. Estimated X-Ray Doses to the Uterus/ Embryo from Common Fluoroscopic Procedures Dose to Fluoroscopic Cerebral angiographl <0.1 Cardiac angiographyb,( 0.65 223 (± 11n8) Single-vessel PTCAb,c 0.60 1023 (± 952) Double-vessel PTCAb,c 0.90 1186 (± 593) Upper gastrointestinal seriesd 0.56 136 ,e 0.06 192 Barium enemab,f,9 20-40 289-311 aWagner, 1997. Calculations based on data of Gorson, 1984. cFinci, 1987. dSuleiman, 1991n.


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Obstentrics_Williams. Upper gastrointestinal seriesd 0.56 136 ,e 0.06 192 Barium enemab,f,9 20-40 289-311 aWagner, 1997. Calculations based on data of Gorson, 1984. cFinci, 1987. dSuleiman, 1991n. eBased on female data from Rowley, 1987. fAssumes embryo in radiation field for entire examination. 9Bednarek, 1983. SD = standard deviation. Angiography and vascular embolization may occasionally be necessary for trauma and for serious maternal disorders, especially renal disease (Wortman, 2013). As before, a greater distance from the embryo or fetus lowers the exposure and risk. These x-ray images are usually performed by obtaining a spiral of 360-degree images that are postprocessed in multiple planes. Of these, the axial image remains the most commonly obtained


Obstentrics_Williams

Obstentrics_Williams. These x-ray images are usually performed by obtaining a spiral of 360-degree images that are postprocessed in multiple planes. Of these, the axial image remains the most commonly obtained CT (MDCT) images are now standard for common clinical indications. The most recent detectors have 16 or 64 channels, and multidetector protocols may result in increased dosimetry compared with traditional CT imaging. Several imaging parameters have an efect on exposure (Brenner, 2007). These include pitch, kilovoltage, tube current, collimation, number of slices, tube rotation, and total acquisition time. If a study is performed with and without contrast, the dose is doubled because twice as many images are obtained. Fetal exposure is also dependent on factors such as maternal size as well as fetal size and position. And as with plain radiography, the closer the target area is to the fetus, the greater the delivered dose.


Obstentrics_Williams

Obstentrics_Williams. Cranial CT scanning is the most commonly performed study in gravidas. It is used for neurological disorders as discussed in Chapter 60 (p. 1156) and with eclampsia as noted in Chapter 40 (p. 724). Nonenhanced CT scanning is commonly used to detect acute hemorrhage within the epidural, subdural, or subarachnoid spaces (Fig. 46-3). Because of the distance from the fetus, radiation dosage is negligible (Goldberg-Stein, 2012). Abdominal procedures are more problematic. Hurwitz and associates (2006) employed a 16-channel multidetector FIGURE 46-3 A 37-year-old with intrapartum eclampsia at term. renchymal hematoma (H) with intraventricular extension (arrow heads). The midline (arrow) is shifted to the right due to mass effect from the hematoma. (Reproduced with permission from Kho KA: Diagnostic and operative laparoscopy. In Yeomans ER, Hoffman BL, Gilstrap LC III, et al (eds): Cunningham and Gilstrap's Operative


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Obstentrics_Williams. Obstetrics 3rd ed, New York McGraw-Hili Education, 2017.) scanner to calculate fetal exposure at 0 and 3 months' gestation using a phantom model. Calculations were made for three commonly requested procedures in pregnant women (Table 46-7). he pulmonary embolism protocol has the same dosimetry exposure as the ventilation-perfusion (V/Q) lung scan discussed on page 908. Because of the pitch used, the appendicitis protocol has the highest radiation exposure, however, it is very useful clinically when MR imaging is not available. Using a similar protocol in 67 women with suspected appendicitis, Lazarus and coworkers (2007) reported sensitivity of 92 percent, specificity of 99 percent, and a negative-predictive value of 99 percent. Here, dosimetry was markedly decreased compared with standard appendiceal imaging because of a different pitch. his is discussed further in Chapter 54 (p. 1052). Last, for suspected urolithiasis, the multidetector-scan protocol is used if sonography is


Obstentrics_Williams

Obstentrics_Williams. standard appendiceal imaging because of a different pitch. his is discussed further in Chapter 54 (p. 1052). Last, for suspected urolithiasis, the multidetector-scan protocol is used if sonography is nondiagnostic. Using a similar protocol, White and colleagues (2007) identified urolithiasis in 13 of 20 women at an average of 26.5 weeks. Finally, as shown in


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Obstentrics_Williams. TABLE 46-7. Estimated Radiation Dosimetry with , 6-Channel Multidetector Computed Pulmonary embolism 0.20-0.47 0.61-0.66 Data from Hurwitz, 2006. FIGURE 46-4 This woman in her third trimester was involved in a high-speed motor vehicle accident. A. Maximum intensity projection acquired for maternal indications readily identifies fetal skull fractures (arrows). B.3-D reformatted CT image in a bone algorithm demonstrates the fetal skeleton from data acquired during the maternal examination. Again, the arrow marks one fracture site. (Reproduced with permission from Bailey AA, Twickler OM: Perioperative imaging. In Yeomans ER, Hoffman BL, Gilstrap LC III, et al (eds): Cunningham and Gilstrap'S Operative Obstetrics 3rd ed. New York: McGraw-Hili Education; 201o7. Photo contributor: Dr. Travis Browning.) Figure 46-4, abdominal tomography is performed if indicated in the pregnant woman with severe trauma (Matzon, 2015; Shakerian, 2015).


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Obstentrics_Williams. Most experience with chest CT scanning is with suspected pulmonary embolism. The most recent recommendations for its use in pregnancy from the Prospective Investigation of Pulmonary Embolism Diagnosis-PIOPED-II investigators were summarized by Stein and associates (2007). They found that pulmonary scintigraphy-the V/Q scan-was recommended at that time for pregnant women by 70 percent of radiologists and chest CT angiography by 30 percent. Indeed, scintigraphy is still recommended by the American Thoracic Society for gravidas with a normal chest x-ray (Leung, 2012). hat said, most agree that multidetector-CT angiography has improved accuracy because of increasingly faster acquisition times (Brown, 2014). Others have reported a higher use rate for CT angiography and emphasize that dosimetry is similar to that with V/Q scintigraphy (Brenner, 2007; Greer, 2015; Hurwitz, 2006). Controversies on this topic continue, recognizing that fetal radiation doses are lower with CT angiography


Obstentrics_Williams

Obstentrics_Williams. is similar to that with V/Q scintigraphy (Brenner, 2007; Greer, 2015; Hurwitz, 2006). Controversies on this topic continue, recognizing that fetal radiation doses are lower with CT angiography compared with the V/Q scan, but maternal chest radiation doses are substantially higher with CT scanning (van Mens, 2017). We prefer MDCT scanning initially for suspected pulmonary embolism (Chap. 52, p. 1016).


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Obstentrics_Williams. CT pelvimetry is used by some before attempting breech vaginal delivery (Chap. 28, p. 542). he fetal dose approaches 0.015 Gyor 1.5 rad, but use of a low-exposure technique may reduce this to 0.0025 Gy or 0.25 rad. hese can be given intravenously or taken orally. Intravenous contrast agents are considered category B by the FDA. The types of intravenous contrast employed for imaging today are iodinated and low osmolality, thus, they cross the placenta to the fetus. With water-soluble iodinated contrast, no cases of neonatal hypothyroidism or other adverse efects have been documented (American College of Radiology, 2015). Oral contrast preparations, typically containing iodine or barium, have minimal systemic absorption and are unlikely to afect the fetus.


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Obstentrics_Williams. hese studies are performed by "tagging" a radioactive element to a carrier that can be injected, inhaled, or swallowed. For example, the radioisotope technetium-99m may be tagged to red blood cells, sulfur colloid, or pertechnetate. he method used to tag the agent determines fetal radiation exposure. he amount of placental transfer is obviously important, but so is renal clearance because of fetal proximity to the maternal bladder. Measurement of radioactive technetium is based on its decay, and the units used are the curie (Ci) or the becquerel (Bq). Dosimetry is usually expressed in millicuries (mCi). he efective tissue dose is expressed in sievert units (Sv) with conversion as discussed in Table 46-4: 1 Sv = 100 rem = 100 rad.


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Obstentrics_Williams. Depending on the physical and biochemical properties of a radioisotope, an average fetal exposure can be calculated (Wagner, 1997; Zanzonico, 2000). Commonly used radiopharmaceuticals and estimated absorbed fetal doses are given in Table 46-8. The radionuclide dose should be kept as low as possible (Adelstein, 1999; Zanotti-Fregonara, 2017). Exposures vary with gestational age and are greatest earlier in pregnancy for most radiopharmaceuticals. One exception is the later efect ofiodine-131 on the fetal thyroid (Wagner, 1997). Discussed earlier, some still use the ventilation-perfusion lung scan for suspected pulmonary embolism. It is also used if CT angiography is nondiagnostic. Perfusion is measured with injected 99T c-macroaggregated albumin, and ventilation is measured with inhaled xenon-127 or xenon-133. Fetal exposure with either is negligible (Chan, 2002; 110untford, 1997).


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Obstentrics_Williams. Thyroid scanning with iodine-123 or iodine-131 seldom is indicated in pregnancy. With trace diagnostic doses used, however, fetal risk is minimal. Importantly, therapeutic radioiodine in doses to treat Graves disease or thyroid cancer may cause fetal thyroid ablation and cretinism. amCi = millicuries. To convertto mrad, mUltiply by 100. bExposures are generally greater prior to 12 weeks compared with increasing gestational ages. cSome measurements account for placental transfer. dThe uptake and exposure of 1 increases with gestational age. Tc04 = pertechnetate; TI = thallium. Data from Adelstein, 1999; Schwartz, 2003; Stather, 2002; Wagner, 1997; Zanzonico, 2000.


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Obstentrics_Williams. dThe uptake and exposure of 1 increases with gestational age. Tc04 = pertechnetate; TI = thallium. Data from Adelstein, 1999; Schwartz, 2003; Stather, 2002; Wagner, 1997; Zanzonico, 2000. he sentinel lymphoscintigram, which uses 99mT c-sulfur indispensable in everyday practice. Its wide-ranging clinical colloid to detect the axillary lymph node most likely to have uses are further discussed in Chapter 10 and in most other secmetastases from breast cancer, is a commonly used preoperative tions of this book. study in nonpregnant women (Newman, 2007; Spanheimer, 2009; Wang, 2007). As shown in Table 46-8, the calculated dose is approximately 0.014 mSv or 1.4 mrad, which should MAGNETIC RESONANCE IMAGING not preclude its use during pregnancy.


Obstentrics_Williams

Obstentrics_Williams. Magnetic resonance technology does not use ionizing radiation, and its application is cited throughout this book. Advantages include high soft-tissue contrast, ability to characterize tissue, Of all of the major advances in obstetrics, the development of and acquisition of images in any plane-particularly axial, sagsonography for study of the fetus and mother certainly is one of ittal, and coronal. An entire section in Chapter 10 (p. 215) is the greater achievements. The technique has become virtually devoted to mechanisms that generate MR images. The most recent update of the expert panel on MR safety of the American College of Radiology was summarized by Kanal and colleagues (20l3). The panel concluded that no harmful human efects are reported from MR imaging. Similar conclusions were reached by the Canadian Task Force on Preventive Health Care (Patenaude, 2014).


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Obstentrics_Williams. Early studies found diferences in blastocyst formation of early murine embryos exposed to MR imaging with 1.5 T (T = tesla) (Chew, 2001). When operated within standardized limits, maternal and fetal imaging can be safely performed at clinical magnet strengths-3 T and below. MR imaging can be used, regardless of trimester: (1) if the information cannot be obtained with another nonionizing modality, namely sonography, (2) if the results of the study will guide maternal or fetal management during pregnancy, and (3) if the imaging cannot be delayed until the woman is no longer pregnant. he decision to use a magnetic field strengthr> 1.5 T may be made for specific maternal indications. Early work also suggests imaging at 3 T can improve fetal assessment (Victoria, 2016). A magnetic ield strength up to 4 T appears safe in animals (Magin, 2000). Vadeyar and associates (2000) reported no demonstrable fetal heart rate pattern changes during MR imaging of gravidas. Studies evaluating children


Obstentrics_Williams

Obstentrics_Williams. up to 4 T appears safe in animals (Magin, 2000). Vadeyar and associates (2000) reported no demonstrable fetal heart rate pattern changes during MR imaging of gravidas. Studies evaluating children exposed in utero have shown no deleterious efects (Clements, 2000; Kok, 2004; Reeves, 2010).


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Obstentrics_Williams. Contraindications to MR imaging include internal cardiac pacemakers, neurostimulators, implanted defibrillators and infusion pumps, cochlear implants, shrapnel or other metal in biologically sensitive areas, some intracranial aneurysm clips, and any metallic foreign body in the eye. Of more than 51,000 nonpregnant patients scheduled for MR imaging, Dewey and colleagues (2007) found that only 0.4 percent had an absolute contraindication to the procedure. Elemental gadolinium cheates are used to create paramagnetic contrast. hese cross the placenta and are found in the fetus, placenta, and nnionic fluid (Oh, 2015). In doses approximately 10 times the human


Obstentrics_Williams

Obstentrics_Williams. FIGURE 46-5 Multipara at 29 weeks' gestation with suspected appendicitis. A. Coronal T2-weighted magnetic resonance image demonstrates severe hydronephrosis (arrow) and perinephric fluid (white arrowhead) suggesting caliceal rupture. The normal appendix is seen laterally (black arrowhead). B. Coronal computed tomography (CT) better defines the source of obstruction as an 8-mm radiopaque stone at the ureteropelvic junction (blue arrow) and distal to the hydronephrosis (white arrow). C and D. In the same woman, more anterior coronal and sagittal CT images show the expected displacement of a noninflamed appendix yellow arrow) into the upper abdomen with advancing gestation. FIGURE 46-6 Nullipara at 27 weeks' gestation. A. Axial T2-weighted MR image demonstrates mild fetal unilateral ventriculomegaly involving the left lateral ventricle (arrow). B. Sagittal T2-weighted MR image demonstrates normal development of the corpus callosum (arrowheads) and vermis (arrow).


Obstentrics_Williams

Obstentrics_Williams. B. Sagittal T2-weighted MR image demonstrates normal development of the corpus callosum (arrowheads) and vermis (arrow). TABLE 6-9. Guidelines for Diagnostic Imaging During Pregnancy and Lactation Sonography and magnetic resonance (MR) imaging are not associated with fetal risk and are preferred options for imaging in pregnancy In general, radiation exposure during radiography, computed tomography (C), or nuclear medicine imaging delivers a dose much lower than that associated with fetal harm. If needed to supplement sonography or MR imaging or if more readily available, these should not be withheld With MR imaging, gadolinium contrast use should be restricted unless it significantly improves diagnostic accuracy to benefit fetal or matenal outcome Data from American College of Obstetricians and Gynecologists, 20ln7a.


Obstentrics_Williams

Obstentrics_Williams. Data from American College of Obstetricians and Gynecologists, 20ln7a. dose, a gadolinium-based contrast agent caused slight developmental delay in rabbit fetuses. De Santis and associates described 26 women given a gadolinium derivative in the first trimester without adverse fetal efects (Kanal, 2013). According to Briggs and colleagues (2015), the American College of Obstetricians and Gynecologists (2017a), and the American College of Radiology (2015), routine use of gadolinium is not recommended unless there are potential benefits that outweigh fetal risks. his recommendation stems from a possible dissociation of the toxic gadolinium ion from its ligand in amnionic Ruid and potential prolonged exposure of the fetus.


Obstentrics_Williams

Obstentrics_Williams. In some cases, MR imaging may be complementary to CT, and in others, MR imaging is preferable. Maternal central nervous system abnormalities, such as brain tumors or spinal trauma, are more clearly seen with MR imaging. As discussed in Chapter 40 (p. 723), MR imaging has provided valuable insights into the pathophysiology of preeclampsia (Twickler, 2007; Zeeman, 2003, 2014). It is invaluable in the diagnosis of neurological emergencies (Edlow, 2013). To evaluate the maternal abdomen and retroperitoneal space, MR imaging is a superb technique. It is chosen by many to determine the degree and extent of placenta accreta and its variants (Chap. 41, p. 780). It has been employed for detection and localization of adrenal tumors, renal lesions, gastrointestinal lesions, and pelvic masses in pregnancy. For evaluating neoplasms of the chest, abdomen, and pelvis in pregnancy, it has particular value (Boyd, 2012; Tica, 2013). MR urography has been used successfully for renal urolithiasis


Obstentrics_Williams

Obstentrics_Williams. in pregnancy. For evaluating neoplasms of the chest, abdomen, and pelvis in pregnancy, it has particular value (Boyd, 2012; Tica, 2013). MR urography has been used successfully for renal urolithiasis (Mullins, 2012). As discussed in Chapter 37 (p. 672), CT and MR imaging are useful for evaluation of puerperal infections, but MR imaging provides better visualization of the bladder Rap area following cesarean delivery (Brown, 1999; Twickler, 1997). MR imaging now includes evaluation of right lower quadrant pain in pregnancy, specifically appendicitis (Fig. 46-5) (Baron, 2012; Dewhurst, 2013; Furey, 2014; Pedrosa, 2009; Tsai, 2017). Investigators have also found other disorders of the gastrointestinal tract to be easily diagnosed with MR imaging (Chap. 54, p. 1043). Finally, cardiac MR imaging has shown promise in investigating normal physiology, complex defects, and cardiomyopathies (Kramer, 2015; Nelson, 2015; Stewart, 2016).


Obstentrics_Williams

Obstentrics_Williams. Fetal MR imaging provides a complement to sonography (LaiferNarin, 2007; Sandrasegaran, 2006). According to Zaretsky and associates (2003a), MR imaging can be used to image almost all elements of the standard fetal anatomical survey. The most frequent fetal indications for MR imaging are evaluation of complex abnormalities of the brain, chest, and genitourinary system (Williams, 2017). Reichel (2003), Twickler (2002), and others have validated its use for fetal central nervous system anomalies and biometry (Fig. 46-6). Caire and coworkers (2003) reported its merits for fetal genitourinary anomalies. Hawkins and colleagues (2008) described MR imaging in 21 fetuses with renal anomalies and oligohydramnios. Zaretsky and associates (2003b) noted that fetal-weight estimation was more accurate using MR imaging than with sonography. Fetal movement is less problematic with faster acquisitions. Morphology is primarily assessed with fast T2-weighted sequences such as HASTE-Half-Fourier


Obstentrics_Williams

Obstentrics_Williams. using MR imaging than with sonography. Fetal movement is less problematic with faster acquisitions. Morphology is primarily assessed with fast T2-weighted sequences such as HASTE-Half-Fourier Acquisition Single Shot Turbo Spin Echo, or SSFSE-Single hot Fast Spin Echo. Fetal indications and indings of MR imaging are discussed more extensively in Chapter 10 (p. 217) and throughout this book.


Obstentrics_Williams

Obstentrics_Williams. he American College of Obstetricians and Gynecologists (2017 a) has reviewed the efects of radiographic, sonographic, and magnetic-resonance exposure during pregnancy. Its suggested guidelines are shown in Table 46-9. Adelstein 5J: Administered radionuclides in pregnancy. Teratology 59:236, 1999 American College of Obstetricians and Gynecologists: Guidelines for diagnostic imaging during pregnancy and lactation. Committee Opinion No. 723, October 2017a American College of Obstetricians and Gynecologists: Nonobstetric surgery during pregnancy. Committee Opinion No. 696, April 2017b American College of Radiology: ACR manual on contrast media. Version 10.1, 20t15 Amis E5 Jr, Butler PF, Applegate E, et al: American College of Radiology white paper on radiation dose in medicine. J Am Coll Radiol 4(5):272, 2007 Asizare M, 2015; A1ipour M, Taghavi M, et al: Bilateraltlaparoscopic adrenalectomy in a pregnant women with Cushing's syndrome. Urol J II(5): 191t1, 2014


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Obstentrics_Williams. Asizare M, 2015; A1ipour M, Taghavi M, et al: Bilateraltlaparoscopic adrenalectomy in a pregnant women with Cushing's syndrome. Urol J II(5): 191t1, 2014 Azevedo JL, Azevedo Oe, Miyahira SA, et al: Injuries caused by Veress needle insertion for creation of pneumoperitoneum: a systematic literature review. Surg Endosc 23(7):1428,t2009 Bailey M, Twickler OM: Perioperative imaging. In Yeomans ER, Hofman BL, Gilstrap LC III, et al (eds): Cunningham and Gilstrap's Operative Obstetrics, 3rd ed, New York, McGraw-Hill Education, 2017 Baldwin A, Borowski KS, Brost Be, et al: Antepartum nonobstetrical surgery at :23 weeks' gestation and risk for preterm delivery. Am J Obstet Gynecol 212:232.e1,t2015 Barnard JM, Chain 0, Droste 5, et al: Fetal response to carbon dioxide pneumoperitoneum in the pregnant ewe. Obstet Gynecol 85:669, 1995


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Obstentrics_Williams. Barnard JM, Chain 0, Droste 5, et al: Fetal response to carbon dioxide pneumoperitoneum in the pregnant ewe. Obstet Gynecol 85:669, 1995 Baron KT, Arleo EK, Robinson C, et al: Comparing the diagnostic performance of MRI versus CT in the evaluation of acute nontraumatic abdominal pain during pregnancy. Emerg RadioIt19(6):519, 2012 Bednarek DR, Rudin 5, Wong, et al: Reduction of fluoroscopic exposure for the air-contrast barium enema. Br J Radiol 56:823, 1983


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Obstentrics_Williams. Boyd CA, Benarroch-Gampel J, Kilic G, et al: Pancreatic neoplasms in pregnancy: diagnosis, complications, and management. J Gastrointest Surg 16(5):1064,t2012 Brenner OJ, Hall JH, Phil 0: Computed tomography-an increasing source of radiation exposure. N Engl J Med 357:2277, 2007 Brent L: Carcinogenic risks of prenatal ionizing radiation. Semin Fetal Neonatal Med 19(3):203,t2014 Brent L: Developmental and reproductive risks of radiological procedures utilizing ionizing radiation during pregnancy. Proceedings No. 21 in Radiation Protection in Medicine: Contemporary Issues. Proceedings of the ThirtyFifth Annual Meeting of the National Council on Radiation Protection and Measurements. Arlington, VA, April 7-8, 1999a Brent L: Saving lives and changing family histories: appropriate counseling of pregnant women and men and women of reproductive age, concerning risk of diagnostic radiation exposure during and before pregnancy. Am J Obstet Gynecol 200(1):4, 2009 Brent L: Utilization of


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Obstentrics_Williams. of pregnant women and men and women of reproductive age, concerning risk of diagnostic radiation exposure during and before pregnancy. Am J Obstet Gynecol 200(1):4, 2009 Brent L: Utilization of developmental basic science principles in the evaluation of reproductive risks from pre-and postconception environmental radiation exposures. Teratology 59: 182, 1999b Briggs GG, Freeman RK: Drugs in Pregnancy and Lactation, 10th ed. Philadelphia, Lippincott Williams & Wilkins, 2015 Brown AM, Cronin CG, NiMhuircheartaigh J, et al: Evaluation of imaging quality of pulmonary 64-vlDCT angiography in pregnancy and puerperium. AJR An1 J Roentgenol 202(1):60, 2014 Brown CE, Stettler RW, Twickler 0, et al: Puerperal septic pelvic thrombophlebitis: incidence and response to heparin therapy. Am J Obstet Gynecol 181:143, 1999 Bunyavejchevin 5, Phupong V: Laparoscopic surgery for presumed benign ovarian tumor during pregnancy. Cochrane Database Syst Rev 1:CD005459, 2013 Caire JT, Ramus RM, Magee KP, et


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Obstentrics_Williams. Infants exposed to MRI in utero have a normal paediatric assessment at 9 months of age. Br J Radiol 73 (866):190,t2000 Committee on Biological Efects of Ionizing Radiation: Other somatic and fetal efects. In BEIR V: Efects of Exposure to Low Levels ofIonizing Radiation. Washington, National Academy Press, 1990 Corneille MG, Gallup TM, Bening T, et al: he use of laparoscopic surgery in pregnancy: evaluation of safety and eicacy. Am J Surg 200:363,t2010 Cox TC, Huntington CR, Blair LJ, et al: Laparoscopic appendectomy and cholecystectomy versus open: a study in 1999 pregnant patients. Surg Endosc 30(2):593,t2016 Czeizel E, Pataki T, Rockenbauer M: Reproductive outcome ater exposure to surgery under anesthesia during pregnany. Arch Gynecol Obstet 261: 193, 1998 Daykan Y, Klein Z, Bugin R, et al: Ovarian torsion during pregnancy-perinatal and delivery outcome after surgical treatment. Am J Obstet Gynecol 214:5110,t2016 Dekaban AS: Abnormalities in children exposed to x-irradiation during


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Obstentrics_Williams. Edlow JA, Caplan LR, O'Brien K, et al: Diagnosis of acute neurological emergencies in pregnant and postpartum women. Lancet Neurol 12(2): 175, 2013 Fatum M, Rojansky N: Laparoscopic surgery during pregnancy. Obstet Gynecol Surv 56:50,t2001 Fenig E, Mishaeli M, Kalish Y, et al: Pregnancy and radiation. Cancer Treat Rev 27:1,t2001 Finci L, Meier B, Stefenino G, et al: Radiation exposure during diagnostic catheterization and single-and double-vessel percutaneous transluminal coronary angioplasty. Am J Cardiol 60: 1401, 1987 Furey A, Bailey M, Pedrosa I: Magnetic resonance imaging of acute abdominal and pelvic pain in pregnancy. Top Magn Reson Imaging 23(4):225,t2014 Gazmararian JA, Petersen R, Jamieson OJ, et al: Hospitalizations during preg nancy among managed care enrollees. Obstet Gynecol 100:94, 2002 Gernsheimer T, .McCrae R: Immune thrombocytopenic purpura in pregnancy. Curr Opin Hematol 14:574,t2007


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Obstentrics_Williams. Kramer CM: Role of cardiac MR imaging in cardiomyopathies. J Nucl Med 56 SuppIt4):39S, 2015 Kuo e, Jamieson DJ, McPheeters ML, et al: Injury hospitalizations of pregnant women in the United States, 2002. Am J Obstet Gynecoltl96:t161, 2007 Laifer-Narin S, Budorick NE, Simpson LL, et al: Fetal magnetic resonance imaging: a review. Curr Opin Obstet Gynecol 19: 151, 2007 Lazarus E, Mayo-Smith W, Mainiero MB, et al: CT in the evaluation of nontraumatic abdominal pain in pregnant women. Radiology 244:784,t2007 Leung AN, Bull TM, Jaeschke R, et al: American Thoracic Sociery documents: an oicial American horacic Sociery/Sociery of Thoracic Radiology Clinical Practice Guidelines-evaluation of suspected pulmonary embolism in pregnancy. Radiology 262(2):635,t20t12 Levine LD, Schulkin J, Mercer BM, et al: Role of the hospital and maternal fetal medicine physician in obstetrical inpatient care. Am J Perinatol 33(2):123,t2016 Magin L, Le JK, Klintsova A, et al: Biological efects of long duration,


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Obstentrics_Williams. et al: Role of the hospital and maternal fetal medicine physician in obstetrical inpatient care. Am J Perinatol 33(2):123,t2016 Magin L, Le JK, Klintsova A, et al: Biological efects of long duration, highfield (4T) MRI on growth and development in the mouse. J Magn Res Imaging 12(1):t140,t2000 Mala T, Harsem NK, Rostad S, et al: Perforation of the pregnant uterus during laparoscopy for suspected internal herniation after gastric bypass. Case Rep Obstet Gynecol 20t181, 2014 Matzon JL, Lutsky KF, Ricci EK, et al: Considerations in the radiologic evaluation of the pregnant orthopaedic patient. J Am Acad Orthop Surg 23(8):485, 20t15 Mazonakis M, Damilakis J, Varveris H, et al: A method of estimating fetal dose during brain radiation therapy. Int J Radiat Oncol Bioi Phys 44:455, 1999 Mazonakis M, Varveris H, Damilakis J, et al: Radiation dose to conceptus resulting from tangentil breast irradiation. Int J Radiat Oncol Bioi Phys 55:386, 2003 Mazze RI, Kallen B: Reproductive ourcome after


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Obstentrics_Williams. M, Varveris H, Damilakis J, et al: Radiation dose to conceptus resulting from tangentil breast irradiation. Int J Radiat Oncol Bioi Phys 55:386, 2003 Mazze RI, Kallen B: Reproductive ourcome after anesthesia and operation during pregnancy: a registry study of 5405 cases. Am J Obstet Gynecol 161:1t178, 1989 Miller MA, Mazzaglia PJ, Larson L, et al: Laparoscopic adrenalectomy for phaeochromocytoma in a twin gestation. J Obstet Gynaecol 32(2): 186, 2012 Moore HB, Juarez-Colunga E, Bronsert M, et al: Efect of pregnancy on adverse outcomes after general surgery. JAMA Surg 150(7):637,t2015 Mountford PJ: Risk assessment of the nuclear medicine patient. Br J Radiol 100:671, 199 Mullins JK, Semins MJ, Hayams ES, et al: Half Fourier single-shot turbo-echo magnetic resonance urography for the evaluation of suspected renal colic in pregnancy. Urology 79(6):1252,t20t12 National Council on Radiation Protection and Measurements: Medical X-ray, electron beam and gamma-ray protection for energies up


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Obstentrics_Williams. of suspected renal colic in pregnancy. Urology 79(6):1252,t20t12 National Council on Radiation Protection and Measurements: Medical X-ray, electron beam and gamma-ray protection for energies up to 50 MeV. Report No. 102, Bethesda, 1989 National Research Council: Health efects of exposure to low levels of ionizing radiation BEIR V. Committee on the Biological Efects of Ionizing Radiations. Board on Radiation Efects Research Commission on Life Sciences. Washington, National Academy Press, 1990 National Research Council: Health risks from exposure to low levels of ionizing radiation BEIR VII Phase 2. Committee to assess health risks from exposure to low levels of ionizing radiation. Board on Radiation Efects Research Division on Earth and Life Studies. Washington, National Academies Press, 2006 Nelson DB, Stewart RD, Matulevicius SA, et al: he efects of maternal position and habitus on maternal cardiovascular parameters as measured by cardiac magnetic resonance. Am J


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Obstentrics_Williams. Academies Press, 2006 Nelson DB, Stewart RD, Matulevicius SA, et al: he efects of maternal position and habitus on maternal cardiovascular parameters as measured by cardiac magnetic resonance. Am J PerinatoIt32(14):t1318, 2015 Newman EA, Newman LA: Lymphatic mapping techniques and sentinel lymph node biopsy in breast cancer. Surg Clin North Am 87:353, 2007 Nuyttens J], Prado L, Jenrette JM, et al: Fetal dose during radiotherapy: clinical implementation and review of the literature. Cancer Radiother 6:352, 2002 Oh Y, RobertS H, Schabel Me, et al: Gadolinium chelate contrast material in pregnancy: fetal biodistribution in the nonhuman primate. Radiology 276(1):t110,t2015 O'Rourke N, Kodali BS: Laparoscopic surgery during pregnancy. Curr Opin Anaesthesiol 19:254, 2006 Otake M, Yoshimaru H, Schull WJ: Severe mental retardation among the prenatally exposed survivors of the atomic bombing of Hiroshima and Nagasaki: a comparison of the old and new dosimetry systems. Radiation Efects Research


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Obstentrics_Williams. WJ: Severe mental retardation among the prenatally exposed survivors of the atomic bombing of Hiroshima and Nagasaki: a comparison of the old and new dosimetry systems. Radiation Efects Research Foundation, Technical Report No. 16-8 , 198 Patenaude Y, Pugash 0, Lim K, el al: Sociery of Obstetricians and Gynaecologists of Canada. he use of magnetic resonance imaging in the obstetric patient. J Obstet Gynaecol Can 36(4):349, 2014 Pearl JP, Price RR, Tonkin E, et al: SAGES guidelines for the use of laparoscopy during pregnancy. Surg Endosc 31t(10):3767,t20t1 Pedrosa I, Lafornara M, Pandharipande PV, et al: Pregnant patients suspected of having acute appendicitis: efect of MR imaging on negative laparotomy rate and appendiceal rate. Radiology 250(3):749, 2009


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Obstentrics_Williams. General Considerations and Maternal Evaluation 913 Phupong V, Bunyavejchewin S: Gasless laparoscopic surgery for ovarian cyst in a second trimester pregnant patient with a ventricular septal defect. Surg Laparosc Endosc Percutan Tech 17:565,t2007 Prado L, Nelson SJ, Nuyttens J], et al: Clinicl implementation of the AAPM Task Group 36 recommendations on fetal dose from radiotherapy with photon beams: a head and neck irradiation case report. J Appl Clin Med Phys 1(1):t1,t2000 Preston DL, Cullings H, Suyama A, et al: Solid cancer incidence in atomic bomb survivors exposed in utero or as young children. J Natl Cancer Inst 100:428,t2008 Reedy MB, Galan HL, Bean-Lijewski JD, et al: Maternal and fetal efects of laparoscopic insuiation in the gravid baboon. J Am Assoc Gynecol Laparose 2:399, 1995 Reedy MB, Kallen B, Kuehl TJ: Laparoscopy during pregnancy: a study of ive fetal outcome parameters with use of the Swedish Health Registry. Am J Obstet Gynecol 177:673, 1997 Reeves MJ, Brandreth M,


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Obstentrics_Williams. Reedy MB, Kallen B, Kuehl TJ: Laparoscopy during pregnancy: a study of ive fetal outcome parameters with use of the Swedish Health Registry. Am J Obstet Gynecol 177:673, 1997 Reeves MJ, Brandreth M, Whitby EH, et al: Neonatal cochlear function: measurement after exposure to acoustic noise during in utero MR imaging. Radiology 257(3):802,t2010 Reichel TF, Ramus RM, Caire JT, et al: Fetal central nervous system biometry on MR imaging. AJR Am J RoentgenoIt180:1t155, 2003 Reynolds JD, Booth JV, de la Fuente S, et al: A review of laparoscopy for nonobstetric-related surgery during pregnancy. Curr Surg 60: 164, 2003 Ribic-Pucelj M, Kobal B, Peternelj-Marinsek S: Surgical treatment of adnexal masses in pregnancy: indications, surgical approach and pregnancy ourcome. J Reprod Med 3, 2007 Rollins MD, Chan KJ, Price R: Laparoscopy for appendicitis and cholelithiasis during pregnancy. Surg Endosc 18:237, 2004 Rowley A, Hill SJ, Watkins A, et al: An investigation into the levels of radiation


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Obstentrics_Williams. MD, Chan KJ, Price R: Laparoscopy for appendicitis and cholelithiasis during pregnancy. Surg Endosc 18:237, 2004 Rowley A, Hill SJ, Watkins A, et al: An investigation into the levels of radiation exposure in diagnostic examinations involving luoroscopy. Br J ,1t98 Sandrasegaran K, Lall CG, Aisen AA: Fetal magnetic resonance imaging. Curr Opin Obstet Gynecol 18:605,t2006 Schwartz JL, vfozurkewich EL, Johnson TM: Current management of patients with melanoma who are pregnant, want to get pregnant, or do not want to get pregnant. Cancer 97:2130, 2003 Shakerian R, Thomson BN, Judson R, el al: Radiation fear: impact on compliance with trauma imaging guidelines in the pregnant patient. J Trauma Acute Care Surg 78(1):88, 20t15 Silvestri MT, Pettker CM, Brousseau EC, et al: Morbidiry of appendectomy and cholecystectomy in pregnant and nonpregnant women. Obstet Gynecol 11t8(6):1261,t201t1 Sisodia M1, Del Carmen MG, Boruta OM: Role of minimally invasive surgery in the management of adnexal


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Obstentrics_Williams. and cholecystectomy in pregnant and nonpregnant women. Obstet Gynecol 11t8(6):1261,t201t1 Sisodia M1, Del Carmen MG, Boruta OM: Role of minimally invasive surgery in the management of adnexal masses. Clin Obstet Gynecol 58(1t):66, 2015 Sociery for Maternal-Fetal Medicine (SMFM), Sciscione A, Berghella V, et al: Society for Maternal-Fetal Medicine (SMFM) Special Report: the maternalfetal medicine subspecialists' role within a health care system. Am J Obstet Gynecolt21 (6):607,t2014 Sorahan T, Lancashire RJ, Temperton DH, et al: Childhood cancer and paternal exposure to ionizing radiation: a second report from the Oxford Survey of Childhood Cancers. Am J Ind Med 1,t1995 Spanheimer PM, Graham MM, Sugg SL, et al: Measurement of urerine radiation exposure from lymphoscintigraphy indicates safety of sentinel lymph node biopsy during pregnancy. Ann Surg Oncol 16(5):t1143,t2009 Stather JW, Phipps A W, Harrison JD, et al: Dose coeicients for the embryo and fetus following intakes of radio


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Obstentrics_Williams. safety of sentinel lymph node biopsy during pregnancy. Ann Surg Oncol 16(5):t1143,t2009 Stather JW, Phipps A W, Harrison JD, et al: Dose coeicients for the embryo and fetus following intakes of radio nuclides by the mother. J Radiol Prot 22: 1, 2002 Stein, PO, Woodard PK, Weg JG, et al: Diagnostic pathways in acute pulmonary embolism: recommendations of the PIOPED II investigators. Radiology 242(1):15,t200 Steinbrook A, Bhavani-Shankar K: Hemodynamics during laparoscopic surgery in pregnancy. Anesth Analg 93: 15 0, 2001 Stepp K, Falcone T: Laparoscopy in the second trimester of pregnancy. Obstet Gynecol Clin North Am 31:485, 2004 Stewart RD, Nelson DB, Matulevicius SA, et al: Cardiac magnetic resonance to assess the impact of maternal habitus on cardiac remodeling during pregnancy. Am J Obstet Gynecol 214(5):640.el, 2016 Stovall M, Blackwell CR, Cundif J, et al: Fetal dose from radiotherapy with photon beams: report of AAPM Radiation Therapy Committee Task Group No. 36. Med Phys


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Obstentrics_Williams. J Obstet Gynecol 214(5):640.el, 2016 Stovall M, Blackwell CR, Cundif J, et al: Fetal dose from radiotherapy with photon beams: report of AAPM Radiation Therapy Committee Task Group No. 36. Med Phys 22:63, 1995 Stroup SP, Altamar HO, L'Esperance JO, et al: Retroperitoneoscopic radical nephrectomy for renal-cell carcinoma during twin pregnancy. J Endourol 21t:735,t2007 Strzelczyk, J, Damilakis J, Marx MV, et al: Facts and controversies abour radiation exposure, part 2: low-level exposures and cancer risk. J Am Coil Radiol 4:32,t200 Suleiman OH, Anderson J, Jones B, et al: Tissue doses in the upper gastrointestinal examination. Radiology 178(3):653, 1991


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Obstentrics_Williams. Tica A, Tica os, Satoiu A, et al: Large pancreatic mucinous cystic neoplasm during pregnancy: what should be done? Gynecol Obstet Invest 5(2): 132, 2013 Tsai R, Raptis C, Fowler KJ, et al: MRI of suspected appendicitis during pregnancy: interradiologist agreement, indeterminate interpetation, and the meaning of non-visualization of the appendix. Br J Radiol 90: 1079, 2017 Twickler OM, Cunningham FG: Central nervous system indings in preeclampsia and eclampsia. In Lyall F, Belfort M (eds): Pre-eclampsiaEtiology, and Clinical Practice. Cambridge, Cambridge University Press, 2007, p 424 Twickler OM, Reichel T, McIntire DO, et al: Fetal central nervous system ventricle and cisterna magna measurements by magnetic resonance imaging. Am J Obstet Gynecol 187:927, 2002 Twickler OM, Setiawan AT, Evans R, et al: Imaging of puerperal septic thrombophlebitis: a prospective comparison ofMR imaging, CT, and sonography. AJR Am J RoentgenoIt169:t1t039, 1997


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Obstentrics_Williams. Twickler OM, Setiawan AT, Evans R, et al: Imaging of puerperal septic thrombophlebitis: a prospective comparison ofMR imaging, CT, and sonography. AJR Am J RoentgenoIt169:t1t039, 1997 Vadeyar SH, Moore RJ, Strachan BK, et al: Efect of fetal magnetic resonance imaging on fetal heart rate patterns. Am J Obstet Gynecol 182:666, 2000 van Mens TE, Scheres LJ, de Jong PG, et al: Imaging for the exclusion of pulmonary embolism in pregnancy. Cochrane Database Syst Rev 1:CD011053, 2017 Victoria T, Johnson AM, Edgar JC, et al: Comparison berween 1.5-T and 3-T MRI for fetal imaging: is there an advantage to imaging with a higher field strength? AJR Am J Roentgenol 206: 195, 2016 Vilos GA, Ternamian A, Dempster J, et al: Laparoscopic entry: a review of techniques, technologies, and complications. J Obstet Gynaecol Can 29:433,t2007 Wagner LK, Lester RG, Saldana LR: Exposure of the Pregnant Patient to Diag nostic Radiation. Philadelphia, Medical Physics Publishing, 1997


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Obstentrics_Williams. Wang L, YutJM, Wang YS, et al: Preoperative lymphoscintigraphy predicts the successful identification but is not necessary in sentinel lymph nodes biopsy in breast cancer. Ann Surg Oncol 14(8):2215,t200 Webb KE, Sakhel K, Chauhan SP, el al: Adnexal mass during pregnancy: a review. Am J Perinatol 32(11):1010, 2015 White WlvI, Zite NB, Gash J, et l:Low-dose computer tomography for the evaluation ofAank pain in the pregnant population. J EndoutoI21:1255, 2007 WO JY, Viswanathan AN: Impact of radiotherapy on fertility, pregnancy, and neonatal outcomes in female cancer patients. Int J Radiat Oncol Bioi Phys 3(5):1304,t2009


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Obstentrics_Williams. Wortman A, Miller DL, Donahue TF, et al: Embolization of renal hemorrhage in pregnancy. Obstet Gynecol 121(Pt 2 Supplt1):480, 2013 Zanotti-Fregonara P, Hindie E: Performing nuclear medicine examinations in pregnant women. Phys Med 43:159,t2017 Zanzonico PB: Internal radionuclide radiation dosimetry: a review of basic concepts and recent developments. J Nucl Med 41t:297,t2000 Zaretsky M, McIntire 0, Twickler OM: Feasibility of the fetal anatomic and maternal pelvic survey by magnetic resonance imaging at term. Am J Obstet Gynecol 189:997, 2003a Zaretsky M, Reichel TF, McIntire DO, et al: Comparison of magnetic resonance imaging to ultrasound in the estimation of birth weight at term. Am J Obstet GynecoIt189:1017, 2003b Zeeman GG, Cipolla MJ, Cunningham FG: Cerebrovascular (patho)physiology in preeclampsia. In Taylor RN, Roberts JM, Cunningham FG, et al (eds): Chesley's Hypertensive Disorders in Pregnancy, 4th ed. Amsterdam, Elsevier, 2014, p 269


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Obstentrics_Williams. Zeeman GG, Hatab M, Twickler D: Maternal cerebral blood Row changes in pregnancy. Am J Obstet Gynecol 189:968,t2003 OBSTETRICALINTENSIVE CARE ....................915 ACUTE PULMONARY EDEMA ......................917 ACUTE RESPIRATORY DISTRESS SYNDROME ........918 SEPSIS SYNDROME.............................. 921 TRAUMA....................................... 925 THERMAL INJURY............................... 930 CARDIOPULMONARY RESUSCITATION.............931 The pregnant women is exposed to the same possibiliy of injuy as at other times, the prognosis not being naturaly altered except that abortion tequenty occurs.


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Obstentrics_Williams. -J. Whitridge Williams (1903) hese observations made more than a century ago are less applicable toda) to critically ill pregnant women because of current intensive care capabilities. For example, severe medical, surgical, and obstetrical disorders complicating pregnancy are frequently managed by a multidisciplinary team for optimal care. It is axiomatic that obstetricians and other members of the health-care team must have a working knowledge of the unique considerations for pregnant women. Some of those discussed in Chapter 46 include pregnancy-induced physiological changes, alterations in normal laboratory values, and consideration for the second patient-the fetus. Because these critically ill women are usually young and in good health, their prognosis is generally better than that of many other patients admitted to intensive care units (ICUs) (Gafney, 2014).


Obstentrics_Williams

Obstentrics_Williams. In the United States each year, 1 to 3 percent of pregnant women require critical care services, and the risk of death during such admissions ranges from 2 to 11 percent (American College of Obstetricians and Gynecologists, 2017b). hose with pregnancy-associated complications-especiall) hemorrhage and hypertension-have the greatest need for intensive care (Chantry, 2015; Gafney, 2014; Guntupalli, 2015a,b). That said, many antepartum admissions are for nonobstetrical reasons, and these include diabetes, pneumonia or asthma, heart disease, chronic hypertension, pyelonephritis, and thyrotoxicosis (Guntupalli, 2015b; Zeeman, 2006). Additionally, intrapartum and postpartum critical care for hypertensive disorders, hemorrhage, sepsis, or cardiopulmonary complications is often required. In instances of life-threatening hemorrhage, surgical procedures may be necessary, and close proximity to a delivery-operating room is paramount. For women who are undelivered, fetal well-being is also better


Obstentrics_Williams

Obstentrics_Williams. of life-threatening hemorrhage, surgical procedures may be necessary, and close proximity to a delivery-operating room is paramount. For women who are undelivered, fetal well-being is also better served by this close proximity, especially because many are delivered preterm (Kilpatrick,r2016).


Obstentrics_Williams

Obstentrics_Williams. • Organization of Critical Care he concept and development of critical care for all aspects of medicine and surgery began in the 1960s. The National Institutes of Health held a Consensus Conference (1983) and the Society of Critical Care Medicine (1988, 1999) subsequently established guidelines for ICUs. Especially pertinent to obstetrics, these costly units prompted the evolution of a step-down intermediate care unit. hese latter units were designed for patients who did not require intensive care, but who needed a higher level of care than that provided on a general ward. The American College of Critical Care Medicine and the Society of Critical Care Medicine (1998) have published guidelines for these units (Table TABLE 47-1 . Guidelines for Conditions That Could Qualify for Intermediate Care


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Obstentrics_Williams. TABLE 47-1 . Guidelines for Conditions That Could Qualify for Intermediate Care Cardiac: for possible infarction, stable infarction, stable arrhythmias, mild-to-moderate congestive heart failure, hypertensive urgency without end-organ damage Pulmonary: stable patients for weaning and chronic ventilation, patients potential for respiratory failure who are otherwise stable Neurological: stable central nervous system, neuromuscular, or neurosurgical conditions that close monitoring Drug overdose: hemodynamically stable Gastrointestinal: stable bleeding, liver failure with stable vital signs Endocrine: diabetic ketoacidosis, thyrotoxicosis that requires frequent monitoring Surgical: postoperative from major procedures or complications that require close monitoring Miscellaneous: early sepsis, patients who require closely titrated intravenous fluids, pregnant women with severe Data from Nasraway, 1998 .


Obstentrics_Williams

Obstentrics_Williams. Data from Nasraway, 1998 . Although the evolution of critical care for obstetrical patients has generally followed developments just described, there are no speciic guidelines. Most hospitals employ a blend of these concepts, and in general, units can be divided into three types.


Obstentrics_Williams

Obstentrics_Williams. First, in most hospitals, severely ill women are transferred to medical or surgical ICUs that are operated by specialists oten certified in critical care medicine. Admissions or transfers to these units are situation-speciic and based on the acuity of care needed and on the ability of the facility to provide it. For example, pregnant women who require ventilatory support, invasive monitoring, or pharmacological support of circulation are typically transferred to an ICU (Chantry, 2015). Another example is the neurological ICU (Sheth, 2012). In an earlier review of more than 25 tertiarycare referral institutions, approximately 0.5 percent of obstetrical patients were transferred to these types ofICUs (Zeeman, 2006).


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Obstentrics_Williams. A second type is the obstetrical intermediate care unit, sometimes referred to as a high-dependency care unit (HDU). One example is found at Parkland Hospital. Located within the labor and delivery unit, it has designated rooms stafed by experienced personnel. The two-tiered system incorporates the guidelines for intermediate and intensive care. Care is provided by maternal-fetal medicine specialists and nurses with experience in critical care obstetrics. As needed, this team is expanded to include other obstetricians and anesthesiologists, hospitalists, gynecological oncologists, pulmonologists, cardiologists, surgeons, and other medical and surgical subspecialists (Stevens, 2015). Many tertiary-care centers have developed similar intermediate care units and use selected triage to ICUs. Guidelines


Obstentrics_Williams

Obstentrics_Williams. Last, obstetrical ICUs are full-care ICUs but are operated by obstetrical and anesthesia personnel in the labor and delivery unit. Only a few obstetrical sevices have these capabilities (Zeeman, 2003, 2006). For smaller hospitls, transfer to a medical or surgical ICU is usually preferable, and sometimes transfer to another hospital is necessary. s discussed, indications for admission to these types of critical care units vary, however, patient mix for these units is similar (Table 47-2). he American College of Obstetricians and Gynecologists (2017b) has summarized criticl obstetrical care implementation depending on hospital size and technical facilities. Data obtained during pregnancy with pulmonary artery catheterization (PAC) have contributed immensely to the understanding of normal pregnancy hemodynamics and pathophysiology of common obstetrical conditions. These include preeclampsia-eclampsia, acute respiratory distress syndrome,


Obstentrics_Williams

Obstentrics_Williams. TABLE 47-2. Comparison of Acuity of Patient Mix for Obstetrical Critical Care Shown in Percent Care Unit Surgical.lCU Factor {n = 483)a {n = 81.3)b for such transfers must follow the federal Emergency Medical Hypertension Treatment and Labor Act (EMTALA) guidelines. According to the American Academy of Pediatrics and the American College of Obstetricians and Gynecologists (2017), the minimal monitoring required for a critically ill patient during transport includes continuous pulse oximetry, electrocardiography, and regular assessment of vital signs. They must have secure venous access, and those who are mechanically ventilated must have endotracheal tube position confirmed and secured. Left uterine displacement and supplemental oxygen is applied routinely during transport of antepartum patients. Continuous fetal heart rate or tocodynamic monitoring is individualized. Preg na ncy-Related 0.2 2 aData from Zeeman, 2003.


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Obstentrics_Williams. Preg na ncy-Related 0.2 2 aData from Zeeman, 2003. bData from Baskett, 2009; Keizer, 2006; Paxton, 2014; Small, 201n2; Stevens, 2006; Vasquez, 2007. (Columns of indications do not total 100 percent because some diagnoses are not listed. and amnionic-fluid embolism (Clark, 1988, 1995, 1997; Cunningham, 1986, 1987; Hankins, 1984, 1985). Also, because of these studies, most have concluded that such monitoring is seldom necessary (American College of Obstetricians and Gynecologists, 2013; Gidwani, 2013; Magder, 2015). In nonobstetrical patients, randomized trials of nearly 5000 subjects have shown no benefits with PAC (Harvey, 2005; National Heart, Lung, and Blood Institute, 2006; Sandham, 2003). According to a Cochrane Database review, no randomized trials have used PAC for preeclampsia management (Li, 2012). he overall mechanisms, benefits, and risks were recently reviewed by Magder (2015).


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Obstentrics_Williams. Formulas for deriving some hemodynamic parameters are shown in Table 47-3. hese measurements can be indexed for body size by dividing by body surface area (BSA). Normal values for nonpregnant adults are used, but with the caveat that these may not necessarily reflect changes induced by the more "passive" uteroplacental perfusion. In a landmark investigation, Clark and colleagues (1989) used PAC to obtain cardiovascular measurements in healthy pregnant women and again in these same women when nonpregnant (Chap. 4, p. 62). Because increased blood volume and cardiac output are compensated by decreased vascular resistance and increased pulse rate, ventricular performance remains within the normal range at term.


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Obstentrics_Williams. Cardiac complications are a common indication for ICU admission of pregnant women (Guntupalli, 2015b). Evaluation of cardiac unction is frequently performed using echo cardiography. his technology is indispensable in interrogating cardiac anatomy and especially right-ventricular unction (Krishnan, 2015; hiele, 2015). It is considered in more detail in Chapter 49 (p. 951), and some norml values are listed in the Appendix (p. 1261). A working knowledge of cardiovascular physiology in pregnancy is paramount to understanding the pathophysiology of gestational complications discussed later in this chapter and throughout the book. TABLE 47-3. Formulas for Deriving Various Cardiopulmonary Parameters


Obstentrics_Williams

Obstentrics_Williams. TABLE 47-3. Formulas for Deriving Various Cardiopulmonary Parameters BSA = body surface area (m2); CVP = central venous pressure (mm Hg); DBP = diastolic blood pressure; HR = heart rate (beats/min); MAP = mean systemic arterial pressure (mm Hg); MPAP = mean pulmonary artery pressure (mm Hg); PCWP = pulmonary capillary wedge pressure (mm Hg); SBP = systolic blood pressure. Critical Care and Trauma 91.7


Obstentrics_Williams

Obstentrics_Williams. Critical Care and Trauma 91.7 The incidence of pulmonary edema complicating pregnancy averages 1 in 500 deliveries at tertiary referral centers. The two general causes are: (1) cardiogenic, namely, hydrostatic edema caused by high pulmonary capillary hydraulic pressures, and (2) noncardiogenic, that is, permeability edema caused by capillary endothelial and alveolar epithelial damage. In pregnancy, noncardiogenic pulmonary edema is more common. Taken in toto, studies in gravidas indicate that more than half who develop pulmonary edema have some degree of sepsis syndrome in conjunction with tocolysis, severe preeclampsia, or obstetrical hemorrhage combined with vigorous luid therapy (O'Dwyer, 2014; hornton, 2011).


Obstentrics_Williams

Obstentrics_Williams. lthough cardiogenic pulmonary edema is less frequent, common precipitating causes include resuscitation for hemorrhage and vigorous treatment of preterm labor. In one study, the causes in 51 women with pulmonary edema were cardiac failure, tocolytic therapy, iatrogenic luid overload, and preeclampsia (Sciscione, 2003). In another study, more than half of cases were associated with preeclampsia, and the other three causes had equal distribution (Hough, 2007). In still another study of 53 cases, 83 percent were caused by hypertensive disorders, 11 percent cardiac, and 6 percent sepsis (O'Dwyer, 2015). Although used less commonly today, tocolytic therapy with �-mimetic drugs at one time was the cause of up to 40 percent of pulmonary edema cases (DiFederico, 1998; Gandhi, 2014; Jenkins, 2003).


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Obstentrics_Williams. Endothelial activation is the common denominator that is associated with preeclampsia, sepsis syndrome, and acute hemorrhage-or frequently combinations thereof-and they are the most common predisposing factors to pulmonary edema (T able 47-4). As discussed, these clinical scenarios are often associated with corticosteroids given to induce fetal lung TABLE 47-4. Some Causes and Associated Factors for Pulmonary Edema in Pregnancy Noncardiogenic permeability edema: endothelial activation with capillary-alveolar leakage Sepsis syndrome: pyelonephritis, metritis Tocolytic therapy: �-mimetics, MgS04


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Obstentrics_Williams. Noncardiogenic permeability edema: endothelial activation with capillary-alveolar leakage Sepsis syndrome: pyelonephritis, metritis Tocolytic therapy: �-mimetics, MgS04 Cardiogenic pulmonary edema: myocardial failure with maturation along with vigorous luid replacement and tocolytic therapy (Thornton, 2011). Parenteral 3-agonists are indisputably linked to pulmonary edema. Studies have also associated magnesium sulfate given for preeclampsia (Gandhi, 2014; Wilson, 2014; Xiao, 2014). Combined therapy is also causative. In one study of nearly 800 women given magnesium sulfate for preterm labor, 8 percent developed pulmonary edema, and half of this afected group had also received terbutaline (Samol, 2005).


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Obstentrics_Williams. Ventricular failure causing pulmonary edema in pregnancy is usually associated with some form of gestational hypertension. Although it can be due to congenital or acquired anatomical defects, diastolic dysfunction is frequently from chronic hypertension, obesity, or both (Jessup, 2003; Kenchaiah, 2002). In these women, acute systolic hypertension exacerbates diastolic dysfunction and causes pulmonary edema (Dennis, 2012; Gandhi, 2001). Of note, concentric and eccentric hypertrophy is two-to threefold more common in black women compared with white women (Drazner, 2005). In a case-control study of 28 gravidas with preeclampsia and pulmonary edema, half of them were undelivered (Gandhi, 2014).


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Obstentrics_Williams. In women with an underlying cardiomyopathy, heart failure is commonly precipitated by preeclampsia, hypertension, hemorrhage and anemia, and puerperal sepsis (Cunningham, 1986; Sibai, 1987). In many of these, when echocardiography is done later, systolic function is normal as measured by ejection fraction, but evidence for diastolic dysunction can often be found (Aurigemma, 2004). The use of brain natriuretic peptide (BNP) has not been evaluated extensively in pregnancy (Seror, 2014). his neurohormone is secreted from ventricle myocytes and fibroblasts with distention seen in heart failure. In nonpregnant patients, values < 100 pgl mL have an excellent negative-predictive value, and levels >500 pg/mL have an excellent positivepredictive value. It is problematic that levels frequently are 100 to 500 pg/mL, and thus nondiagnostic (Ware, 2005). Values for N-terminal BNP and atrial natriuretic peptide (ANP) are both elevated with preeclampsia (Szabo, 2014; Tihtonen, 2007). his is


Obstentrics_Williams

Obstentrics_Williams. are 100 to 500 pg/mL, and thus nondiagnostic (Ware, 2005). Values for N-terminal BNP and atrial natriuretic peptide (ANP) are both elevated with preeclampsia (Szabo, 2014; Tihtonen, 2007). his is discussed in greater detail in Chapter 4 (p. 63), and normal values for pregnancy are given in the Appendix (p. 1259).


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Obstentrics_Williams. Acute pulmonary edema requires emergency care. Furosemide is given in 20-to 40-mg intravenous doses along with therapy to control severe hypertension. Further treatment depends on whether a woman is ante-or postpartum. A live fetus prohibits the use of cardioactive drugs that might rapidly lower peripheral resistance and in turn severely diminish uteroplacental circulation. he cause of cardiogenic failure is determined by echocardiography, which will help direct further therapy. Acute pulmonary edema is not, per se, an indication for emergency cesarean delivery.


Obstentrics_Williams

Obstentrics_Williams. Acute lung injury that causes a form of severe permeability pulmonary edema and respiratory failure is termed acute respiratory distress syndrome (ARDS). This is a pathophysiological continuum from mild pulmonary insuiciency to dependence on high inspired oxygen concentrations and mechanical ventilation. Uniform criteria for its diagnosis are lacking, and thus the incidence is variably reported for pregnancy. In one survey of the Nationwide Inpatient Sample, 2808 pregnant women with ARDS were identified (Rush, 2017). he incidence ranged from 36 to 60 cases per 100,000 births, and the maternal mortality rate was 9 percent. In its most extreme form, requiring ventilatory support, the associated mortality rate is 45 percent. This rate can be as high as 90 percent if caused or complicated by sepsis (Phua, 2009). Although gravidas are younger and usully healthier thn the overall population, they still have mortality rates of 25 to 40 percent (Catanzarite, 2001; Cole, 2005). Finally, if


Obstentrics_Williams

Obstentrics_Williams. by sepsis (Phua, 2009). Although gravidas are younger and usully healthier thn the overall population, they still have mortality rates of 25 to 40 percent (Catanzarite, 2001; Cole, 2005). Finally, if ARDS develops antepartum, the perinatal mortality rate is correspondingly high.


Obstentrics_Williams

Obstentrics_Williams. Most investigators define ARDS as radiographically documented pulmonary iniltrates, a ratio of arterial oxygen tension to the fraction of inspired oxygen (Pao2:Fio2) <200, and no evidence of heart failure (Mallampalli, 2010; hompson, 2017). Revised by international consensus, the Berlin Dinition was described by the ARDS Definition Task Force (2012) and includes categories of mild, moderate and severe. To date, for most interventional studies, a working diagnosis of acute lung injuy is made when the Pao2:Fio2 ratio is <300 and is coupled with dyspnea, tachypnea, oxygen desaturation, and radiographic pulmonary infiltrates (Wheeler, 2007). ARDS is a pathophysiological description that begins with an acute lung injury from various causes (Table 47-5). In pregnant TABLE 47-5. Some Causes of Acute Lung Injury and Respiratory Failure in Pregnant Women Pneumonia: bacterial, viral, aspiration Sepsis syndrome: chorioamnionitis, pyelonephritis, puerperal infection, septic abortion


Obstentrics_Williams

Obstentrics_Williams. Pneumonia: bacterial, viral, aspiration Sepsis syndrome: chorioamnionitis, pyelonephritis, puerperal infection, septic abortion Hemorrhage: shock, massive transfusion, transfusion- Embolism: amnionic fluid, trophoblastic disease, air, fat Data from Cole, 2005; Duarte, 2014; Golombeck, 2006; Lapinsky, 2015; Martin, 2006; Sheffield, 2005; Sibai, 20104; Snyder, 201n3; Zeeman, 2003, 2006. women, sepsis and difuse infectious pneumonia are the two most common single-agent ARDS causes. Pyelonephritis, puer peral pelvic infection, and chorioamnionitis are the most frequent causes of sepsis. As discussed on page 917, severe preeclampsia and obstetrical hemorrhage are also commonly associated with permeability edema. Importantly, more than half of pregnant women with ARDS have some combination of sepsis, hemor rhage, shock, and luid overload. The contribution of tranosion related acute lung injuy (TAIl) is unclear (Chap. 41, p. 791).


Obstentrics_Williams

Obstentrics_Williams. Endothelial injury in the lung capillaries releases cytokines that recruit neutrophils to the inflammation site. Here, they elaborate more cytokines to worsen tissue injury. There are three stages of ARDS development. First, the exudative phase follows widespread injury to microvascular endothelium, including the pulmonary vasculature, and there is also alveolar epithelial injury. These result in increased pulmonary capillary perme ability, surfactant loss or inactivation, diminished lung volume, and vascular shunting with resultant arterial hypoxemia. Next, the ibroprolierative phase usually begins 3 to 4 days later and lasts up to day 21. Last, theibrotic phase results from healing, and despite this, the long-term prognosis for pulmonary func tion is surprisingly good (Herridge, 2003; Levy, 2015).


Obstentrics_Williams

Obstentrics_Williams. With pulmonary injury, the clinical condition depends largely on the insult magnitude, the ability to compensate for it, and the disease stage. For example, soon after the initial injury, physical findings are absent except perhaps hyperventilation. And at irst, arterial oxygenation usually is adequate. Pregnancy-induced mild metabolic alkalosis may be accentuated by hyperventilation. With worsening, clinical and radiological evidence for pulmonary edema, decreased lung compliance, and increased intrapulmonary blood shunting become apparent. Progressive alveolar and interstitial edema develop with extravasation of inflammatory cells and erythrocytes.


Obstentrics_Williams

Obstentrics_Williams. Ideally, pulmonary injury is identified at this early stage, and speciic therapy is directed at the underlying insult. Further progression to acute respiratory failure is characterized by marked dyspnea, tachypnea, and hypoxemia. Additional lung volume loss results in worsening of pulmonary compliance and increased shunting. Difuse abnormalities are heard by auscultation, and a chest radiograph characteristically demonstrates bilateral lung involvement (Fig. At this phase, the injury ordinarily would be lethal in the absence of ventilatory support. When shunting exceeds 30 percent, severe refractory hypoxemia develops along with metabolic and respiratory acidosis that can result in myocardial irritability, dysfunction, and cardiac arrest.


Obstentrics_Williams

Obstentrics_Williams. Reduced ARDS mortality rates have resulted from advances in care of the critically ill (Levy, 2015). his requires close attention to: (1) recognizing and treating underlying medical and surgical disorders, (2) minimizing procedures and their complications, (3) administering prophylaxis against venous thromboembolism, gastrointestinal bleeding, aspiration, and central venous catheter infection, (4) promptly diagnosing nosocomial infections, and (5) providing adequate nutrition. FIGURE 47-1 Anteroposterior chest radiograph of a secondtrimester pregnant woman with marked bilateral parenchymal and pleural opacification secondary to acute respiratory distress syndrome (ARDS) due to pyelonephritis.


Obstentrics_Williams

Obstentrics_Williams. In cases of severe acute lung injury, providing adequate oxygenation of peripheral tissues is balanced against maneuvers that further aggravate lung injury. At least intuitively, increasing oxygen delivery should produce a corresponding increase in tissue uptake, but this is diicult to measure. Support of systemic perfusion with intravenous crystalloid and blood is imperative. As discussed earlier, the trial conducted by the National Heart, Lung, and Blood Institute (2006) showed that pulmonary artery catheter use did not improve outcomes. Because sepsis is commonplace in lung injury, vigorous antimicrobial therapy is given for infection, and any necrotic tissues are debrided. Oxygen delivery can be greatly improved by correction of anemia. Speciically, each gram of hemoglobin carries 1.25 mL of oxygen when 90-percent saturated. By comparison, increasing the arterial P02 from 100 to 200 mm Hg results in the transport of only 0.1 mL of additional oxygen for each 100 mL of blood.


Obstentrics_Williams

Obstentrics_Williams. Reasonable goals in caring for the woman with severe lung injury are to attain a Pao2 of 60 mm Hg or 90-percent oxygen saturation using an inspired oxygen content < 50 percent and positive end-expiratory pressures < 15 mm Hg. With regard to the pregnancy, it remains controversial whether delivery of the fetus improves maternal oxygenation (Mallampalli, 2010). In a study of 29 women undergoing mechanical ventilation, 10 were delivered while intubated (Lapinsky, 2015). This was associated with a modest improvement in respiratory function in perhaps half, but no factors were identiied that predicted a better outcome.


Obstentrics_Williams

Obstentrics_Williams. Noninvasive ventilation, that is, positive pressure ventilation by face mask, may be efective in some women in early stages of pulmonary insuiciency (Duarte, 2014). Early intubation is preferred in the gravida if respiratory failure is more likely than not, and especially if it appears imminent. Many successful formulas for mechanical ventilation are employed, and initially a tidal volume :;6 mLlkg is optimal (Levy, 2015; Schwaiberger, 2016). High-frequency oscillation ventilation (HFOV) is controversial in ARDS (Ferguson, 2013; Slutsy, 2013). Adjustments are made to obtain a Paoz>60 mm Hg or a hemoglobin oxygen saturation 290 percent and a Pacoz of 35 to 45 mm Hg. Lower levels for Paoz are avoided, because placental perfusion may be impaired (Levinson, 1974).


Obstentrics_Williams

Obstentrics_Williams. For women who require ventilation for any length of time, the maternal mortality rate is 10 to 20 percent. In a study of 51 such women, almost half had severe preeclampsia, and most required intubation postpartum. Eleven were delivered while being ventilated, and another six were discharged undelivered (Jenkins, 2003). here were two maternal deaths, including a woman who died as a complication of tocolytic treatment. In three other reports, maternal mortality rates ranged from 10 to 25 percent (Chen, 2003; Lapinsky, 2015; Schneider, 2003). In most cases, delivery did not improve maternal outcome.


Obstentrics_Williams

Obstentrics_Williams. With severe lung injury and high intrapulmonary shunt fractions, it may not be possible to provide adequate oxygenation with usual ventilatory pressures, even with 100-percent oxygen. Positive end-expiratory pressure is usually successful in decreasing the shunt by recruiting collapsed alveoli. At low levels of 5 to 15 mm Hg, positive pressure can typically be used safely. At higher levels, impaired right-sided venous return can result in decreased cardiac output, lowered uteroplacental perfusion, alveolar overdistention, falling compliance, and barotrauma (Schwaiberger, 2016; Slutsky, 2013).


Obstentrics_Williams

Obstentrics_Williams. As discussed in Chapter 33 (p. 620), extracorporeal membrane oxygenation (ECM 0) has been successfully used for neonatal meconium aspiration syndrome. Preliminary observation suggests that it may be useful in adults with ARDS (Brodie, 2011; Levy, 2015; Peek, 2009). ECMO use has been reported in pregnant women. In one study, 12 patients with inluenza-induced lung failure were treated with ECMO, and of four maternal deaths, three were due to anticoagulation-related hemorrhage (Nair, 2011). In another study, the duration of support in four survivors was 2 to 28 days (Cunningham, 2006). In a review of 29 treated gravidas, 80 percent of cases were due to ARDS, and the maternal and perinatal mortality rate was 28 percent (Anselmi, 2015). Technical aspects of ECMO were reviewed by Brodie and Bacchetta (2011).


Obstentrics_Williams

Obstentrics_Williams. he propensity of the hemoglobin molecule to release oxygen is described by the oyhemoglobin dissociation curve (Fig. 47-2). For clinical purposes, the curve can be divided into an upper oxygen association curve representing the alveolar-capillary environment and a lower oxygen dissociation portion representing the tissue-capillary environment. Shifts of the curve have their greatest efect at the steep portion because they afect oxygen delivery. A rightward shit is associated with decreased hemoglobin ainity for oxygen and hence increased tissue-capillary oxygen :0 60= :l FIGURE 47-2 Oxyhemoglobin dissociation curve. With higher oxygen tension (Pao2) in the pulmonary alveoli, adult hemoglobin is maximally saturated compared with that at the lower oxygen tension in the tissue capillaries. Note that at any given oxygen tension, fetal hemoglobin carries more oxygen than adult hemoglobin, as indicated by percent saturation.


Obstentrics_Williams

Obstentrics_Williams. interchange. Rightward shifts are produced by hypercapnia, metabolic acidosis, fever, and increased 2,3-diphosphoglycerate levels. During pregnancy, the erythrocyte concentration of 2,3-diphosphoglycerate is increased by approximately 30 percent. This favors oxygen delivery to both the fetus and maternal peripheral tissues.


Obstentrics_Williams

Obstentrics_Williams. Fetal hemoglobin has a higher oxygen ainity than adult hemoglobin. As seen in Figure 47-2, its curve is positioned to the left of the adult curve. To achieve 50-percent hemoglobin saturation, the Paoz must be 27 mm Hg in the mother compared with only 19 mm Hg in the fetus. Under normal physiological conditions, the fetus is constantly on the dissociation, or tissue, portion of the curve. Even with severe maternal lung disease and very low Paoz levels, oxygen displacement to fetal tissues is favored. Another example of this comes from pregnant women who live at high altitudes. Here, despite a maternal Paoz of only 60 mm Hg, the fetal Paoz is equivalent to that of fetuses at sea level (Subrevilla, 1971).


Obstentrics_Williams

Obstentrics_Williams. Although mortality outcomes are similar, conservative rather than liberal fluid management is associated with fewer days of mechanical ventilation (Wiedemann, 2006). Some pregnancyinduced physiological changes predispose to a greater risk of permeability edema from vigorous fluid therapy. Colloid oncotic pressure (COP) is determined by serum albumin concentration, and 1 gl dL exerts approximately 6 mm Hg pressure. As discussed in Chapter 4 (p. 68), serum albumin concentrations normally drop in pregnancy. This results in a decline in oncotic pressure from 28 mm Hg in the nonpregnant woman to 23 mm Hg at term and to 17 mm Hg in the puerperium (Benedetti, 1979; Dennis, 2012). With preeclampsia, endothelial activation with leakage causes extravascular albumin loss and lowered serum albumin levels. As a result in these cases, 14 mm Hg postpartum (Zinaman, 1985). hese changes have a significant clinical efect on the colloid oncotic pressure/wedge pressure gradient. Normally, this gradient


Obstentrics_Williams

Obstentrics_Williams. As a result in these cases, 14 mm Hg postpartum (Zinaman, 1985). hese changes have a significant clinical efect on the colloid oncotic pressure/wedge pressure gradient. Normally, this gradient exceeds 8 mm Hg. However, when it is 4 mm Hg or less, the risk for pulmonary edema rises. No benefits are gained by albumin rather than crystalloid infusions in these women (Uhlig, 2014). hese associations were reviewed by Dennis and Solnordal (2012).


Obstentrics_Williams

Obstentrics_Williams. No long-term follow-up studies address gravidas who recover from ARDS. In nonpregnant subjects, risks for impaired global cognitive function at 3 and 12 months are significant (Pandharipande, 2013). Data from nonpregnant patients indicate a 1-to 2-year hiatus before basic normal activity is restored in all. In a 5-year follow-up study, Herridge and associates (201r1) reported normal lung function but signiicant exercise limitation, physical and psychological sequelae, decreased physical quality of life, and increased use of health-care services.


Obstentrics_Williams

Obstentrics_Williams. This syndrome is induced by a systemic inlammatory response to bacteria or viruses or their by-products such as endotoxins or exotoxins. The severity of the syndrome is a continuum or spectrum 47-3). According to the Centers for Disease Control and Prevention (CDC), sepsis caused 6.2 percent of pregnancy-related deaths in the United States from 201r1 to 2013 (Creanga, 2017). It was also a signiicant cause of maternal mortality in Michigan and the United Kingdom (Bauer, 2015; 110hamed-Ahmed, 2015; Nair, 2015).


Obstentrics_Williams

Obstentrics_Williams. Infections that most commonly cause sepsis syndrome in obstetrics are pyelonephritis (Chap. 53, p. 1028), chorioamnionitis and puerperal sepsis (Chap. 37, p. 667), septic abortion (Chap. 18, p. 351), and necrotizing fasciitis (Chap. 37, p. 671). With severe sepsis, the mortality rate in nonpregnant patients is 20 to 35 percent and is 40 to 60 percent with septic shock (Angus, 2013; Munford, 2015). With shock, the mortality rate in pregnancy has been reported to be 30 percent (Mabie, 1997; Snyder, 2013). That said, the maternal mortality risk from sepsis is significantly underestimated (Bauer, 2015; Chebbo, 2016; Mohamed-Ahmed,r2015).


Obstentrics_Williams

Obstentrics_Williams. Most of what is known concerning sepsis pathogenesis comes from study of lipopolysaccharide-LPS or endotoxin (Munford, 2015). The lipid A moiety is bound by mononuclear blood cells, becomes internalized, and stimulates release of mediators and a series of complex downstream perturbations. Clinical aspects of the sepsis syndrome are manifest when cytokines are released that have endocrine, paracrine, and autocrine actions (Angus, 2013; Singer, 2016).


Obstentrics_Williams

Obstentrics_Williams. Although the sepsis syndrome in obstetrics may be caused by several pathogens, most cases represent a small group. For example, pyelonephritis complicating pregnancy caused by Escherichia coli and Klebsiela species commonly is associated with bacteremia and sepsis syndrome (Cunningham, 1987; Snyder, 2013). And although pelvic infections are usually polymicrobial, bacteria that cause severe sepsis syndrome are frequently endotoxin-producing Enterobacteriaceae, most commonly E coli (Eschenbach, 2015). Other pelvic pathogens are aerobic and anaerobic streptococci, Bacteroides species, and Clostridium species. Some strains of group A 3-hemolytic ) SIRS-fever, tachycardia, tachypnea, leukocytosis, leukopenia t::, Organ system dysfunctionacidosis, encephalopathy, oliguria, hypoxemia, coagulopathy Spectrum of Severity FIGURE 47-3 The sepsis syndrome begins with a systemic inflammatory response syndrome (SIRS) in response to infection that may progress to septic shock.


Obstentrics_Williams

Obstentrics_Williams. Spectrum of Severity FIGURE 47-3 The sepsis syndrome begins with a systemic inflammatory response syndrome (SIRS) in response to infection that may progress to septic shock. streptococci and Staphylococcus aureus-including communityacquired methicillin-resistant strains (CA-MRSA)-produce a superantigen that activates T cells to rapidly cause all features of the sepsis syndrome-toxic shock syndrome (Moellering, 2011; Soper, 2011). his is discussed further in Chapter 37 (p. 675).


Obstentrics_Williams

Obstentrics_Williams. drome. Examples include exotoxins from Clostridium pertingens or sordellii, toxic-shock-syndrome toxin-1 (TSST -1) from S au reus, and toxic shock-like exotoxin from group A 3-hemolytic streptococci (Daif, 2009; Soper, 2011). These last exotoxins cause rapid and extensive tissue necrosis and gangrene, especially of the postpartum uterus, and may cause profound cardiovascular collapse and maternal death (Nathan, 1993; Sugiyama, 2010). In a review discussed subsequently, the maternal mortality rate from these infections was 58 percent (Yamada, 2010).


Obstentrics_Williams

Obstentrics_Williams. Thus, the sepsis syndrome begins with an inflammatory response that is directed against microbial endotoxins and exotoxins (Angus, 2013). CD4 T cells and leukocytes are stimulated to produce proinflammatory compounds that include tumor necrosis factor-a (TNF-a), several interleukins, other cytokines, proteases, oxidants, and bradykinin that result in a "cytokine storm" (Russell, 2006). Many other cellular reactions then follow that include stimulation of pro-and antiinflammatory compounds, procoagulant activity, gene activation, receptor regulation, and immune suppression (Filbin, 2009; Moellering, 2011). It is also likely that interleukin-6 (IL-6) mediates myocardial suppression (Pathan, 2004).


Obstentrics_Williams

Obstentrics_Williams. he pathophysiological response to this cascade is selective vasodilation with maldistribution of blood low. Leukocyte and platelet aggregation cause capillary plugging. Worsening endothelial injury causes profound permeability, capillary leakage, and interstitial fluid accumulation (Fig. 47-4). Depending on the degree of injury and inflammatory response, a pathophysiological and clinical continuum evolves as depicted in Figure 47-3. The clinical syndrome begins with subtle signs of Cytokines and other inflammatory mediators lead to endothelial junction separation FIGURE 47-4 Endothelial permeability. The normal interendothelial interface is shown in the left inset. Cytokines and other inflammatory mediators disassemble the cellular junctions, resulting in microvascular leaks (right).


Obstentrics_Williams

Obstentrics_Williams. sepsis from infection and terminates with septic shock, which is defined by hypotension unresponsive to intravenous hydration. In its early stages, clinical shock results primarily from decreased systemic vascular resistance that is not compensated fully by increased cardiac output. Hypoperfusion results in lactic acidosis, decreased tissue oxygen extraction, and end-organ dysfunction that includes acute lung and kidney injury. he sepsis syndrome has myriad clinical manifestations that, at least in part, are dependent on the specific invading microorganism and its particular endo-or exotoxins. Some of the general efects of LPS are as follows: 1. Central nervous system: confusion, delirium, somnolence, coma, combativeness, fever 2. Cardiovascular: tachycardia, hypotension 3. Pulmonary: tachypnea, arteriovenous shunting with dysoxia and hypoxemia, exudative iniltrates from endothelialalveolar damage, pulmonary hypertension 4.


Obstentrics_Williams

Obstentrics_Williams. Cardiovascular: tachycardia, hypotension 3. Pulmonary: tachypnea, arteriovenous shunting with dysoxia and hypoxemia, exudative iniltrates from endothelialalveolar damage, pulmonary hypertension 4. Gastrointestinal: gastroenteritis-nausea, vomiting, and diarrhea; ileus; hepatocellular necrosis-jaundice, transaminitis 5. Renal: prerenal oliguria, azotemia, acute kidney injury, proteinuria 6. Hematological: leukocytosis or leukopenia, thrombocytopenia, activation of coagulation with disseminated intravascular coagulopathy 7. Endocrine: hyperglycemia, adrenal insuiciency 8. Cutaneous: acrocyanosis, erythroderma, bullae, digital gangrene.


Obstentrics_Williams

Obstentrics_Williams. Endocrine: hyperglycemia, adrenal insuiciency 8. Cutaneous: acrocyanosis, erythroderma, bullae, digital gangrene. Thus, although capillary leakage initially causes hypovolemia, if intravenous crystalloid is given at this point, then sepsis hemodynamically can be described as a high cardiac output, low systemic vascular resistance condition (Fig. 47-5). Concomitantly, pulmonary hypertension develops, and despite the high cardiac output, severe sepsis also causes myocardial depression (Munford, 2015; Ognibene, 1988). This is often referred to as the warm phase of septic shock. hese indings are the most common cardiovascular manifestations of early sepsis, but they can be accompanied by some of the other clinical or laboratory aberrations listed above.


Obstentrics_Williams

Obstentrics_Williams. The response to initial intravenous hydration may be prognostic. Most pregnant women who have early sepsis show a salutary response with crystalloid and antimicrobial therapy, and if indicated, debridement of infected tissue. Conversely, if hypotension is not corrected following vigorous luid infusion, then the prognosis is more guarded. At this juncture, if there also is no response to 3-adrenergic inotropic agents, this indicates severe and unresponsive extracellular luid extravasation with vascular insuiciency, overwhelming myocardial depression, or both. Oliguria and continued peripheral vasoconstriction characterize a secondary, cold phase of septic shock that is rarely survived. Another poor prognostic sign is continued renal, pulmonary, and cerebral dysfunction once hypotension has been corrected (Angus, 2013; Chebbo, 2016). The average risk of death increases by 15 to 20 percent with failure of each organ system. With three systems, mortality rates are 70 percent (Martin,


Obstentrics_Williams

Obstentrics_Williams. has been corrected (Angus, 2013; Chebbo, 2016). The average risk of death increases by 15 to 20 percent with failure of each organ system. With three systems, mortality rates are 70 percent (Martin, 2003; Wheeler, 1999).


Obstentrics_Williams

Obstentrics_Williams. FIGURE 47-5 Hemodynamic efects of sepsis syndrome. Values for normal women at term are shown by dots. With early sepsis, there is high cardiac output and low vascular resistance. With fluid resuscitation, cardiac output increases even more, but so does capillary hydraulic pressure. With continued sepsis, there may be myocardial depression to further increase capillary hydraulic pressure. Decreased plasma oncotic pressure (serum albumin [g] x 6 mm Hg) contributes to interstitial lung fluid and endo/epithelialoleak causes alveolar flooding. LVSWI = left ventricular stroke work index; PCWP = pulmonary capillary wedge pressure.