The shape of intestinal segments used for reconstruction

The geometry of intact and detubularized intestinal segments is examined to establish guidelines for estimating the length of bowel required for urinary reconstruction. Because a sphere has the highest ratio of volume to surface area of any geometric form, whenever bowel is detubularized the resulting spherical reservoir will always hold a larger volume than the original cylinder, but unfortunately there is no simplistic formula to estimate this gain. Therefore, tables are presented which calculate the resulting volumes and the gain in volume of detubularized spherically shaped reservoirs used for bladder augmentation and substitution. These tables demonstrate the striking gain in volume that results from detubularizing bowel and provide guidelines for determining the length of bowel segments required for different types of urinary tract reconstruction.