Prostatic abscess

A 72-year-old man presented to the emergency department with a 3-week history of fever, dysuria and rectal pain, along with urinary frequency and urgency. The patient had a 10-year history of type 2 diabetes and benign prostatic hypertrophy, which had been treated with metformin and finasteride, respectively. His examination was remarkable for a palpable, tender fluctuant mass on digital rectal examination of the prostate. He had a white blood cell count of 13.5 (normal range 4–10) × 10⁹/L and a serum creatinine level of 141 (baseline 114) μmol/L. Urine microscopy showed moderate bacteria; large positive leukocyte esterase and positive nitrite results were seen on urine dipstick testing. He was admitted to hospital with a diagnosis of prostatis and started on ceftriaxone administered intravenously (1 g/d).

Because the patient remained febrile for more than 48 hours after treatment was started, we obtained contrast-enhanced computed tomography (CT) of the abdomen and pelvis, which showed heterogeneous attenuation of the prostate gland suggestive of prostatic abscesses (Figure 1; Appendix 1, available at www.cmaj.ca/lookup/doi/10.1503/cmaj.200470/tab-related-content). A urine culture identified Klebsiella pneumoniae. Results for blood culture were negative. A few days after admission, he had difficulty urinating, which required insertion of an indwelling urethral catheter. He underwent a transurethral resection of the prostate and abscess drainage. Histopathology of a biopsy specimen showed inflammation with necrosis and abscess formation. Urinary retention developed after the resection; we prescribed ciprofloxacin administered orally and discharged our patient to home with an indwelling catheter that was removed after 2 days. At a follow-up visit 6 weeks later, he reported no symptoms.

Figure 1:

Coronal computed tomography scan of the abdomen and pelvis in a 72-year-old man with rectal pain and fever, showing prominent right perinephric stranding (blue arrow). Enlargement (7 cm in diameter) and heterogeneous attenuation of the prostate gland with nonenhancing fluid-density collections are suggestive of prostatic abscesses (red arrow).

Prostatic abscesses occur in 2.7% of patients with acute bacterial prostatitis,¹ which occurs most commonly in older patients with diabetes mellitus. Other predisposing factors include long-term catheterization, prostatic manipulation, urethral obstruction and an immunocompromised state.¹ Gram-negative bacilli and Enterococcus are most frequently involved.¹ The presentation of a prostatic abscess is similar to that of bacterial prostatitis;¹ however, fluctuance of the prostate on digital rectal examination can suggest the presence of an underlying abscess. Findings on CT include enlargement and heterogeneous attenuation of the prostate with nonenhancing fluid-density collections. Management options include antibiotics (abscesses < 1 cm),² transrectal ultrasonography-guided aspiration, transurethral resection of the prostate and open drainage.^3,4 Transrectal ultrasonography-guided aspiration is preferred because of its low risk of complications and may be repeated. However, failure is common for aspiration of abscesses greater than 3 cm or with an anechoic or heterogeneous appearance; for these lesions, transurethral resection of the prostate is preferred.⁴ Older age, high-grade fever, urinary retention, positive results for blood cultures and benign prostatic hyperplasia are associated with poor outcomes.¹