In this study we were looking for Risk Factors (RF) for postoperative bladder catheterization in surgical patients. Patients were randomized in two groups with different bladder volumes limits for bladder catheterization; a fixed postoperative bladder volume limit of 500mL or the patients own Maximum Bladder Capacity (MBC). Knowing the patient’s own MBC reduces the incidence of postoperative bladder catheterization1. Of the 1851 patients 196 patients were catheterized (111 in 500group, 85 MBCgroup, RR=0.723, p=0.034). Table 1 is showing univariate analysis of all possible RF for postoperative bladder catheterization. Important RF were age ≥60 years, spinal anesthesia, duration of surgery ≥60 min, surgery on the lower abdomen or lower extremity and a preoperative bladder volume ≥150mL. Multivariate analyses showed that using the MBC in patients ≥60 years made no difference compared to using the 500mL limit. Here the incidence of catheterization is already high (17%) (Table 2). In patients <60 years the most important multivariate adjusted RF for bladder catheterization were spinal anesthesia and surgery ≥60min. Using the MBC reduces the chance be catheterized for patients <60 years (RR=0.62, P=0.009). For patients ≥60 years most important RF were spinal anesthesia and male gender (Table 3). We conclude that for patients ≥60 years it is important to monitor postoperative bladder volumes, especially in males, after spinal anesthesia and after surgery on the lower abdomen or extremity. In patients <60 years it is worth wile to ask them to measure their MBC before the operation. This will lower the chance of postoperative catherization, especially after spinal anesthesia, or when the duration of surgery is ≥60min or after surgery on the lower abdomen or lower extremity. 

09 / The influence of the maximum bladder capacity on risk factors for postoperative urinary catheterization.