Approach

Diagnose prostatitis on the basis of history and clinical examination, supported by the results of diagnostic tests (i.e., urine culture and sensitivity). Urinary tract infection (UTI) is the single greatest risk factor for developing prostatitis. Benign prostatic hyperplasia may result in residual urine that acts as a nidus for infection, so it too may be considered a risk factor for the condition. Acute prostatitis is the most common urological diagnosis in men aged <50 years in the US.[6] It is also the third most common urological diagnosis in men aged >50 years.[7]

History and physical examination

The herald symptoms of acute prostatitis include malaise, fever, chills, and a clinical picture of sepsis accompanied by dysuria, perineal or genital pain, and urinary frequency.[26][27] These may be accompanied by symptoms and signs of urinary obstruction: diminished calibre of urinary stream, slowing stream, even acute urinary retention with the presence of an indwelling Foley catheter. Transrectal prostate biopsy or transurethral resection of the prostate may be associated with the development of prostatic infection, particularly in patients who have an untreated urinary infection at the time of their prostatic procedure.

The most common site for pain is in the region of the prostate and perineum. Pain in the scrotum and testes is also common, while some patients complain of pain in the penis, suprapubically, or in the lower back.[28] In men with acute bacterial prostatitis, digital rectal examination (DRE) will reveal an intensely tender prostate gland. The gland may also feel soft, boggy, and warm to the touch on examination. A DRE should be performed gently; avoid prostatic massage because it can induce bacteraemia and sepsis.​[12][29]​

Laboratory tests

Take a midstream urine culture in patients with acute bacterial prostatitis symptoms to guide diagnosis and tailor antibiotic treatment.​[12][29]​ Urinalysis and urine culture are often the only laboratory tests required in patients with acute bacterial prostatitis. Microscopic examination of the urine may demonstrate the presence of leukocytes and bacteria, and a urine culture is frequently positive in the acute setting. Consider performing blood cultures in febrile patients with acute bacterial prostatitis; they are likely to show the same organism as the urine culture.[12] 

Prostatic massage should not be performed in acute prostatitis as it can induce bacteraemia and sepsis.​[12][29]​ However, in patients with chronic prostatitis (symptoms persisting for more than three months), consider performing quantitative bacterial localisation cultures and microscopy of the segmented urine and expressed prostatic secretion to categorise clinical prostatitis.[12] Known as the Meares and Stamey 4-glass test, this includes bacterial cultures of the initial voided urine (VB1), midstream urine (VB2), expressed prostatic secretions (EPS), and a post-prostatic massage urine specimen (VB3).[30] The VB1 is tested for urethral infection or inflammation, and the VB2 is tested for urinary bladder infection. The EPS are cultured and examined for white blood cells (>10 to 20 per high-power field is considered abnormal). The post-massage urine specimen (VB3) is believed to flush out bacteria from the prostate that remain in the urethra. The Meares and Stamey 4-glass test is, however, rarely performed in contemporary practice because of its expense and complexity.[29]​ The 2-glass test (pre-massage and post-massage specimens) has been shown to have similar diagnostic sensitivity to the 4-glass test.[29][31]

Serum prostate-specific antigen (PSA) can be elevated in some cases of prostatitis. European guidelines recommend against PSA testing because it provides no practical diagnostic information for prostatitis.[12] Raised PSA levels should not be mistaken for prostate cancer.[32] Furthermore, in patients with elevated PSA and grade IV (asymptomatic) prostatitis, a decrease in PSA following treatment does not predict the absence of prostate carcinoma.[33]

Invasive tests

Cystoscopy is not routinely indicated in men with suspected prostatitis. In patients with haematuria or other symptoms (e.g., weight loss), cystoscopic examination of the lower urinary tract (along with urine cytology) is indicated to exclude carcinoma of the bladder.[34]

Perform transrectal ultrasound in patients with acute symptoms who have not responded to antibiotic therapy.[35] The European Association of Urology advises it is unreliable as a diagnostic tool for prostatitis, but may be useful in selected cases to rule out prostatic abscess.[12] It may be useful in making the diagnosis of prostatic cysts, abscesses, and seminal vesicle obstruction.[36][37][38] It may also identify a distended bladder or significant urinary residual in the bladder. Unfortunately, ultrasound cannot unequivocally distinguish between benign and malignant prostatic disease.

Prostate biopsy is not recommended as part of routine work-up and is not advisable in patients with untreated bacterial prostatitis because of the increased risk of sepsis.[12] If a prostate biopsy is considered necessary (for example, if another diagnosis e.g., carcinoma of the prostate is suspected) European guidelines recommend using the transperineal approach because this is associated with lower sepsis rates than transrectal biopsy.[12] Perineal prostate biopsies may also be taken to help in the detection of difficult to culture micro-organisms, but these are recommended only for research purposes. In patients with chronic prostatitis, prostate biopsy cultures have shown no difference compared to asymptomatic controls.[39] Carcinoma of the prostate may be a consideration if the patient has persistent induration, nodularity, or firmness on DRE, or elevated PSA.

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