eMedicine Specialties > Urology > Infections and Related Inflammatory Conditions

Chronic Bacterial Prostatitis: Differential Diagnoses & Workup

Author: Sunil K Ahuja, MD, Chief of Minimally Invasive Urology, Department of Urology, Staff Urologist, Santa Teresa Community Hospital
Contributor Information and Disclosures

Updated: Mar 13, 2008

Differential Diagnoses

Nonbacterial Prostatitis
Prostate Cancer: Biology, Diagnosis, Pathology, Staging, and Natural History
Prostatitis, Bacterial
Urethral Strictures
Urethritis

Other Problems to Be Considered

Acute prostatitis
Prostatic stones
Anatomic obstruction due to prostatic hyperplasia, urinary stricture disease, or bladder neck dysfunction

Workup

Laboratory Studies

• Microscopic examination  
  • Commonly, chronic prostatitis (category II in the 1995 NIH prostatitis classification system) is diagnosed after microscopic examination of the EPS and a positive culture finding after a prostatic massage. If a patient presents with symptoms of an acute urinary tract infection and/or the patient is febrile, an EPS should not be obtained because the patient likely has acute prostatitis. In this situation, a vigorous prostatic massage may result in urinary sepsis.
  • The generally accepted level of WBCs in an EPS for a diagnosis of chronic prostatitis (category II) is more than 10 WBCs/hpf (40X objective) or an observation of clumping WBCs with the presence of oval fat bodies and a positive EPS culture finding. Category III prostatitis is divided into IIIa and IIIb based on whether greater or fewer than 10 WBCs are seen on microscopic examination of the EPS, respectively. However, the management approaches for these two categories do not differ.
  • Finding WBCs in an EPS is not diagnostic of chronic bacterial prostatitis (CBP) because this finding is commonly associated with nonbacterial prostatitis, urethritis, prostatic stones, or recent ejaculation. 
• Positive urine culture findings after a prostatic massage  
  • Performing this procedure helps confirm the diagnosis of CBP.
  • The classic 4-glass Meares-Stamey test for localization of the infection to the prostate is cumbersome and impractical. A more sensitive and practical test that is simpler to perform is preprostatic and postprostatic massage urine culture.²
  • The ejaculate can also be cultured. This may indicate a prostatic infectious source.
  • Carefully observe the culture for a colony count that is 10 times higher in the postprostatic massage culture compared to the preprostatic massage culture, which confirms CBP. This is the widely accepted standard.
  • Perform the prostatic massage during the rectal examination by kneading the prostate from front to back and from lateral to medial until a milky fluid is obtained from the urethra. This may require as long as a minute of fairly vigorous massage; therefore, inform the patient of the intended plan and goal. Sometimes, milking the urethra hastens the appearance of the fluid. Then, touch the fluid to a microscopic slide for examination.
  • The pH of prostatic fluid rises when infection is present, from 6.5 to higher than 8.0.
  • Prostate-specific antigen (PSA) levels are often elevated. Do not construe this finding as an elevation associated with prostate cancer unless the level remains elevated after repeat testing. Repeat testing should be performed 6 weeks after resolution of the prostatitis.

Imaging Studies

• Transrectal ultrasonography 
  • This study is not helpful unless an abscess is present. Abscesses are extremely rare, but if present, patients may also have a high fever and appear quite ill. CT scanning may also be helpful in this situation if transrectal ultrasonography is not available. MRI may also be used but is usually not as readily available in most acute situations.
  • Transrectal ultrasonography findings may also help identify prostatic stones. In certain patients with frequent recurrences, prostatic stones may be a contributing factor in CBP.

Procedures

• Prostate biopsy  
  • This is the most definitive but least practical modality used to diagnose bacterial prostatitis. It is also potentially dangerous for the patient.
  • Viewing the specimen under microscopy can help identify a focal infiltration of inflammatory cells into the prostatic stroma. The specimen also serves as a source from which to culture organisms. However, in the face of an active infection such as acute prostatitis, performing a biopsy could precipitate sepsis. Therefore, prostate biopsy is not recommended as a diagnostic modality.
  • On the other hand, category IV prostatitis is diagnosed using prostate biopsy. Category IV prostatitis is asymptomatic but may be responsible for elevations in PSA levels, resulting in the need for a diagnostic biopsy to help exclude prostate cancer.
• If the patient has frequent recurrences of chronic prostatitis, other tests may help exclude an anatomic obstruction due to prostatic hyperplasia, urinary stricture disease, or bladder neck dysfunction. If this is the case, appropriate treatment (eg, transurethral incision of a urethral stricture, transurethral resection of the prostate or bladder neck) may be indicated.
• Retrograde urethrography, uroflowmetry, and postvoid residual testing are described as follows:  
  • Retrograde urethrography is performed to help confirm the presence of a urethral stricture. It is performed by injecting contrast into the urethral meatus and obtaining pelvic radiography. If a stricture is present, narrowing of urethral caliber is observed.
  • Uroflowmetry is a simple urodynamic test to help evaluate the rate of urine flow over time. It is used in patients with prostatitis to help evaluate for obstruction secondary to a urethral stricture or prostatic enlargement. Results are obtained in graphical form. Normal study results show a rapid rise to a peak and then a gradual drop-off back to baseline. A urethral stricture is indicated by a rapid rise to a low point, a plateau for the remainder of the study, and then a drop-off at the termination of the study. In prostatic enlargement, a wide variety of patterns is present, but the peak flow is usually less than 15 mL/s, and a stop-start pattern may also be present. To help delineate abnormalities and to differentiate a stricture from prostatic enlargement, cystoscopy should be performed.
  • Postvoid residual testing measures the volume of urine left in the bladder immediately after voiding. This volume can be measured by catheterizing the bladder or by using a bladder scanner. Although the results are nonspecific, they can give clues to the presence of lower tract dysfunction, which may require surgical intervention to relieve prostatic obstruction or urethral stricture.

Histologic Findings

Chronic inflammation is common after biopsy specimens have been obtained to help evaluate for prostate cancer. Findings usually include large focal lymphocytic infiltrates amid the normal prostatic stroma; however, biopsy rarely, if ever, is used to diagnose prostatitis. If an asymptomatic patient is found to have inflammation in the prostatic tissue, this is categorized as category IV prostatitis, ie, asymptomatic inflammatory prostatitis.

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