INFLUENCE OF PREOPERATIVE BLADDER CAPACITY AND COMPLIANCE ON THE OUTCOME OF ARTIFICIAL SPHINCTER IMPLANTATION IN PATIENTS WITH NEUROGENIC SPHINCTER INCOMPETENCE

We performed a retrospective study of 23 patients with neurogenic sphincteric incompetence who had undergone implantation of an artificial urinary sphincter to determine if bladder capacity and compliance as determined by cystometrography could predict the need for enterocystoplasty. Study criteria were neurogenic sphincteric incompetence, no previous operations on the lower urinary tract, and performance of preoperative and postoperative cystometrography. Patients were 5 to 17 years old at implantation. Incontinence was caused by myelomeningocele (18 patients), sacral agenesis (3) and spinal cord tumor (2). The 8 patients for whom preoperative cystometric bladder capacity was greater than 60% of the expected capacity for age have been followed for a mean of 60 months. All 8 patients are continent and none required enterocystoplasty. Preoperative bladder compliance exceeded 2 ml./cm. water in all patients (group 1). Of the 15 patients for whom preoperative cystometric bladder capacity was less than 60% of the expected value (group 2, small bladders) 8 followed an average of 72 months had a compliance greater than 2 ml./cm. water and have done well without bladder augmentation. In contrast, 7 patients in this group (46%) required enterocystoplasty: 6 for persistent or recurrent incontinence and 1 for upper tract changes. The average interval between artificial sphincter placement and enterocystoplasty was 14 months. Patients with a small bladder that required augmentation had a preoperative bladder compliance of less than 2 ml./cm. water. We conclude that small bladder capacity, as determined by cystometrography in patients with neurogenic sphincteric incompetence but a bladder compliance of less than 2 ml./cm. water predicts the future need for bladder augmentation. In all other patients, with good medical treatment and followup, the possible adverse effects of a small capacity bladder can be prevented or corrected. With this strategy we have been able to avoid enterocystoplasty with its attending potential complications in 70% of our patients with neurogenic incontinence and favorable urodynamics regardless of preoperative cystometric bladder capacity.