PURPOSE: To prove extravasation after radical retropubic prostatectomy (RRP) nowadays a cystoradiogram is essential. In the present study the diagnostic value of dynamic transrectal ultrasound and cystoradiogram to find an extravasation was compared. MATERIALS AND METHODS: For detection of an extravasation Cystoradiogram and dTRUS were performed in 250 patients who had undergone RRP. TRUS was performed dynamically, that means that the urinary bladder was filled up with common salt solution backwards by using the transurethral catheter. Anastomosis was inspected by transrectal ultrasound. Detectable extravasation was measured and documented. To verify the results a cystoradiogram was carried out afterwards. In cases of detectable extravasation the results of measurement were compared to the results of dTRUS. RESULTS: The mean age was 65 years. An extravasation could be detected in 46 % within the first 7 days and in 18 % after 14 days. At day 21 an extravasation could not be seen in any patient. Seven days postoperative the mean volume of extravasation was 11 ml (3 - 50 ml) and after 14 days 9 ml (3 - 25 ml) for dTRUS. For cystoradiogram 12 ml (3 - 45 ml) and 9 ml (4 - 23 ml), respectively. The average time until catheter removal was 8 days (5 - 35 days). 60 % of the patients were continent immediately after removing the catheter, 40 % were incontinent for not more than 3 months after removal of the catheter (35 % ICS I and 5 % ICS II). A prolonged urinary incontinence and serious postoperative complications were not observed. CONCLUSION: Dynamic transrectal ultrasound is a reliable and reasonable method to identify extravasation after RRP. Furthermore radiation exposure (on average 60 cGy/cm (2)/cystoradiogram) can be avoided by replacing the cystradiogram with dTRUS slips with the dTRUS.