In our series the poppy seed test had the highest sensitivity to detect colovesical fistulas. However, abdominopelvic computerized tomography, colonoscopy and cystoscopy are essential diagnostic procedures because the presence of colon or bladder cancer as an underlying cause of colovesical fistula will determine further therapy.

RESULTSAfter excluding four patients (7%) with bilateral benign renal tumours, six (11%) with metastatic bilateral RCC and three (5%) who had bilateral RN, the cancer-specific outcome was analysed. For 44 patients with bilateral RCC who had surgery with intent to cure and avoid dialysis, 13 (30%) had stage pT1a, 10 (23%) pT1b, nine (17%) pT2 and 12 (27%) pT3 disease. At 5 and 10 years, the cancer-specific survival rates were 86% and 75%, and the local recurrence-free survival rates were 87% and 80%. The median serum creatinine level at the latest follow-up was 1.18 mg/dL in patients after bilateral NSS and 1.40 mg/dL after unilateral NSS and contralateral RN ( P < 0.05). CONCLUSIONSThese long-term data support the concept that NSS, whenever possible bilateral, is the treatment of choice for bilateral synchronous sporadic RCC. NSS provides adequate local tumour control and cancer-specific survival. Preservation of renal function is more efficient with bilateral NSS than with unilateral NSS and contralateral RN.