Post-operative risk factors associated with artificial urinary sphincter infection-erosion

To determine the incidence of infection-erosion associated with the implantation of artificial urinary sphincters (AMS 800) in a high-risk group of patients (post-major pelvic surgery/radiotherapy), and to emphasize the commonly neglected risk factors associated with this complication.

One-hundred-and forty-five male patients aged 55-79 years (mean 71) who had had an AMS 800 artificial sphincter implanted between January 1987 and November 1993 were reviewed. All patients had undergone meticulous surgical technique, intra-operative shave and rigorous scrub, and were given peri-operative antibiotics. The mean follow-up was 34.3 months (range 1-83).

Infection-erosion occurred in 13 patients (9%), of whom 10 are currently available for follow-up. One patient died of his underlying disease (bladder cancer) and two were lost to follow-up. All 13 patients had undergone radical pelvic surgery (radical retropubic prostatectomy, radical cystectomy and abdominoperineal resection); seven patients had also received radiation therapy. Cultures of the infected AMS 800 devices revealed a pleomorphic group of organisms, specifically enteric, Gram-positive and anaerobic organisms. The risk of infection-erosion was found to be increased in the presence of two main factors, improper urethral catheterization and urethral endoscopic manipulation with an activated AMS 800 artificial sphincter in place and exposure to radiation. At the time of revision, nine of the 13 patients were found to have positive urine cultures.

Despite all the precautions taken, there remains a group of patients who are still at a higher risk of infection-erosion due to adverse circumstances that distort the anatomy of the perineal area, impair the host defence mechanisms, and ultimately enable the establishment of the infection-erosion complex. Radiotherapy is known to increase the likelihood of non-mechanical complications, specifically infection-erosion. Extreme care must be taken so that avoidable iatrogenic factors such as improper urethral catheterization and endoscopic manipulation with an activated AMS 800 device in situ are not the cause of 'failure'.