Objective: To determine the incidence of detrusor instability (DI) detected by conventional and ambulatory bladder pressure monitoring, any link between urodynamic findings before and after colposuspension, and between patients' symptoms and the urodynamic findings.
Patients and methods: Sixty-five patients, scheduled to undergo colposuspension on the basis of pure genuine stress incontinence on conventional cystometrography (CMG), also underwent ambulatory monitoring (AM) before surgery. All were requested to return 3 months afterward for repeat CMG and AM in random order. In all, 56 patients completed all assessments before and after surgery. In addition to the urodynamic assessment, the patients' symptoms before and after surgery were compared using a detailed questionnaire.
Results: On AM before surgery, half the patients showed some DI; afterward, the incidence on AM was 70% and on CMG was 27%. However, on AM, 25% of patients who had DI before surgery showed no evidence of it afterward. Of the 19 women who complained of urgency preoperatively, 16 showed DI on preoperative AM. However, of the 37 women denying urgency preoperatively, 12 (32%) also showed evidence of DI on preoperative AM.
Conclusions: There is a significant incidence of DI detected by CMG after colposuspension in patients who are stable before surgery. The incidence of DI on AM was significantly higher than on CMG both before and after surgery. However, the preoperative urodynamic finding of increased DI on AM does not exclusively predict its presence postoperatively on AM or CMG. In addition, a patient history of urgency does not correlate well with the urodynamic findings before or after surgery. Therefore, from this study it appears that the postoperative symptomatic or urodynamic state cannot be predicted reliably from those before surgery.