The shape of the buttocks. A useful guide for selection of anesthesia and patient position in anorectal surgery.

Recognition of the different shapes of the buttocks will help surgeons to appropriately select patients for anorectal surgery. Basically, there are three types of buttocks. In Type A, the mounds of the buttock make a low and gentle slope with the anal verge. In Type B, the mounds of the buttock are high and rise almost straight up from the anal verge. In Type C, the anus is located more anteriorly than normally. Patients with Type A buttocks are ideal candidates to use local anesthesia for hemorrhoidectomy and lateral internal sphincterotomy because it is easy to infiltrate the anesthetic agent into the anal canal. With Type C, this is somewhat more difficult, but no significant problem exists. For Type B buttocks, general or spinal anesthesia is recommended. For Types A and C buttocks, a lithotomy position will give an excellent exposure of the anorectal lumen for stripping the mucosa and submucosa. For Type B buttocks, a prone jack-knife position gives the best exposure.