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Merck Manual

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Gerald L. Andriole


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Prostatitis refers to a disparate group of prostate disorders that manifests with a combination of predominantly irritative or obstructive urinary symptoms and perineal pain. Some cases result from bacterial infection of the prostate gland and others, which are more common, from a poorly understood combination of noninfectious inflammatory factors, spasm of the muscles of the urogenital diaphragm, or both. Diagnosis is clinical, along with microscopic examination and culture of urine samples obtained before and after prostate massage. Treatment is with an antibiotic if the cause is bacterial. Nonbacterial causes are treated with warm sitz baths, muscle relaxants, and anti-inflammatory drugs or anxiolytics.


Prostatitis can be bacterial or, more commonly, nonbacterial. However, differentiating bacterial and nonbacterial causes can be difficult, particularly in chronic prostatitis.

Bacterial prostatitis can be acute or chronic and is usually caused by typical urinary pathogens (eg, Klebsiella, Proteus, Escherichia coli) and possibly by Chlamydia. How these pathogens enter and infect the prostate is unknown. Chronic infections may be caused by sequestered bacteria that antibiotics have not eradicated.

Nonbacterial prostatitis can be inflammatory or noninflammatory. The mechanism is unknown but may involve incomplete relaxation of the urinary sphincter and dyssynergic voiding. The resultant elevated urinary pressure may cause urine reflux into the prostate (triggering an inflammatory response) or increased pelvic autonomic activity leading to chronic pain without inflammation.


Prostatitis is classified into 4 categories (see table NIH Consensus Classification System for Prostatitis). These categories are differentiated by clinical findings and by the presence or absence of signs of infection and inflammation in 2 urine samples. The first sample is a midstream collection. Then digital prostate massage is done, and patients void immediately; the first 10 mL of urine constitutes the 2nd sample. Infection is defined by bacterial growth in urine culture; inflammation is defined by the presence of white blood cells in urine. The use of the term prostatodynia for prostatitis without inflammation is discouraged.


NIH Consensus Classification System for Prostatitis




Urine Finding




Acute bacterial prostatitis

Acute symptoms of urinary infection








Chronic bacterial prostatitis

Recurrent urinary infection with same organism








Chronic prostatitis /chronic pelvic pain syndrome

Primarily symptoms of pain, voiding, and sexual dysfunction











Asymptomatic inflammatory prostatitis

Discovered incidentally during urologic evaluation (eg, prostate biopsy, seminal fluid analysis) for other conditions




* Previously called prostatodynia.

+/ means possibly present; + means present; means absent.

NIH = National Institutes of Health; WBC = white blood cell.

Data from Krieger JN, Nyberg L, Nickel JC: NIH consensus definition and classification of prostatitis. JAMA 282:236–237, 1999.

Symptoms and Signs

Symptoms vary by category but typically involve some degree of urinary irritation or obstruction and pain. Irritation is manifested by frequency and urgency, obstruction, a sensation of incomplete bladder emptying, a need to void again shortly after voiding, or nocturia. Pain is typically in the perineum but may be perceived at the tip of the penis, lower back, or testes. Some patients report painful ejaculation.

Acute bacterial prostatitis often causes such systemic symptoms as fever, chills, malaise, and myalgias. The prostate is exquisitely tender and focally or diffusely swollen, boggy, indurated, or a combination. A generalized sepsis syndrome may result, characterized by tachycardia, tachypnea, and sometimes hypotension.

Chronic bacterial prostatitis manifests with recurrent episodes of infection with or without complete resolution between bouts. Symptoms and signs tend to be milder than in acute prostatitis.

Chronic prostatitis/chronic pelvic pain syndrome typically has pain as the predominant symptom, often including pain with ejaculation. The discomfort can be significant and often markedly interferes with quality of life. Symptoms of urinary irritation or obstruction also may be present. On examination, the prostate may be tender but usually is not boggy or swollen. Clinically, inflammatory and noninflammatory types of chronic prostatitis/chronic pelvic pain syndrome are similar.

Asymptomatic inflammatory prostatitis causes no symptoms and is discovered incidentally during evaluation for other prostate diseases when white blood cells are present in the urine.


  • Urinalysis

  • Prostate massage except possibly in acute bacterial prostatitis

Diagnosis of type I, II, or III prostatitis is suspected clinically. Similar symptoms can result from urethritis, perirectal abscess, or urinary tract infection. Examination is helpful diagnostically only in acute bacterial prostatitis.

Febrile patients with typical symptoms and signs of acute bacterial prostatitis usually have white blood cells and bacteria in a midstream urine sample. Prostate massage to obtain a postmassage urine sample is thought to be unnecessary and possibly dangerous in these patients (although danger remains unproved) because bacteremia can be induced. For the same reason, rectal examination should be done gently. Blood cultures should be obtained in patients who have fever and severe weakness, confusion, disorientation, hypotension, or cool extremities. For afebrile patients, urine samples before and after massage are adequate for diagnosis.

For patients with acute or chronic bacterial prostatitis who do not respond favorably to antibiotics, transrectal ultrasonography and sometimes cystoscopy may be necessary to rule out prostatic abscess or destruction and inflammation of the seminal vesicles.

For patients with types II, III, and IV (nonacute prostatitis) disease, additional tests that can be considered are cystoscopy and urine cytology (if hematuria is also present) and urodynamic measurements (if there is suspicion of neurologic abnormalities or detrusor-sphincter dyssynergia).


  • Treatment varies significantly with etiology

Acute bacterial prostatitis

Nontoxic patients can be treated at home with antibiotics, bed rest, analgesics, stool softeners, and hydration. Therapy with a fluoroquinolone (eg, ciprofloxacin 500 mg orally twice a day or ofloxacin 300 mg orally twice a day) is usually effective and can be given until culture and sensitivity results are known. If the clinical response is satisfactory, treatment is continued for about 30 days to prevent chronic bacterial prostatitis.

If sepsis is suspected, the patient is hospitalized and given broad-spectrum antibiotics IV (eg, ampicillin plus gentamicin). Antibiotics are started after the appropriate cultures are taken and continued until the bacterial sensitivity is known. If the clinical response is adequate, IV therapy is continued until the patient is afebrile for 24 to 48 hours, followed by oral therapy usually for 4 weeks.

Adjunctive therapies include nonsteroidal anti-inflammatory drugs and potentially alpha-blockers (if bladder emptying is poor) and supportive measures such as sitz baths. Rarely, prostate abscess develops, requiring surgical drainage.

Chronic bacterial prostatitis

Chronic bacterial prostatitis is treated with oral antibiotics such as fluoroquinolones for at least 6 weeks. Therapy is guided by culture results; empiric antibiotic treatment for patients with equivocal or negative culture results has a low success rate. Other treatments include anti-inflammatory drugs, muscle relaxants (eg, cyclobenzaprine to possibly relieve spasm of the pelvic muscles), alpha-adrenergic blockers, and other symptomatic measures, such as sitz baths.

Chronic prostatitis/chronic pelvic pain syndrome

Treatment is difficult and often unrewarding. In addition to considering any and all of the above treatments, anxiolytics (eg, selective serotonin reuptake inhibitors [SSRIs], benzodiazepines), sacral nerve stimulation, biofeedback, prostatic massage, and minimally invasive prostatic procedures (such as microwave thermotherapy) have been attempted with varying results.

Asymptomatic inflammatory prostatitis

Asymptomatic prostatitis requires no treatment.

Key Points

  • Prostatitis can be an acute or chronic bacterial infection or a more poorly understood group of disorders typically characterized by irritative and obstructive urinary symptoms, urogenital diaphragm muscle spasm, and perineal pain.

  • Treat patients who have chronic bacterial prostatitis and nontoxic patients who have acute bacterial prostatitis with a fluoroquinolone and symptomatic measures.

  • Hospitalize patients who have acute bacterial prostatitis and systemic symptoms that suggest sepsis and give broad-spectrum antibiotics such as ampicillin plus gentamicin.

  • For men with chronic prostatitis or chronic pelvic pain syndrome, consider anxiolytics (eg, SSRIs, benzodiazepines), sacral nerve stimulation, biofeedback, prostatic massage, and minimally invasive prostatic procedures (eg, microwave thermotherapy).

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