A man with double urinary ducts developed benign prostatic hyperplasia (BPH) and began leaking urine into the abdominal cavity, suggesting that his enlarged prostate triggered the condition, according to a recent Japanese study.

The man was successfully treated with a transurethral resection of the prostate (TURP) procedure and treatment for vesicoureteral reflux — the scientific term for when urine flows backwards from the bladder to the kidneys.

The report, “Extravasation of Urine Associated with Bilateral Complete Ureteral Duplication, Vesicoureteral Reflux and Benign Prostatic Hyperplasia,” suggests that abdominal urinary leakage should be considered in men with flank pain, particularly if they have BPH or a duplicated urinary duct. The study appeared in the journal Urology Case Reports.

Researchers at Japan’s Dokkyo Medical University said the 71-year-old man sought care when he started experiencing stomach pains. Examinations revealed that he had signs of ongoing inflammation. The man said his problems with strained urination had begun about a year earlier, though he had never felt symptoms before that.

Scans revealed that the man had two urinary ducts instead of one — a condition that affects up to 4 percent of the population. Further examinations showed that the man had an enlarged prostate and urine that had leaked into the space surrounding the kidneys. In addition, the patient experienced backward urine flow in both urinary ducts. This is common in people with double ureters, and may also be caused by the blockade of urinary outflow in men with BPH.

At first, the patient had a catheter implanted to relieve pressure and get rid of the urinary leakage. He then had a TURP procedure and was injected with Deflux (dextranomer/hyaluronic acid), which is often used to prevent backward urine flow. The treatment was successful, and three months after the surgery the man showed no signs of urine leaking into the abdomen.

Although the combination of abnormalities presented in this case report is very rare, the research team says that since both BPH and the presence of double urinary ducts are linked to vesicoureteral reflux, physicians should consider the possibility of abdominal urine leakage when a patient with any of these features has flank pain.