Abdominoperineal resection (standard and extralevator) and pelvic exenteration are frequently performed operations. During follow-up, many patients demonstrate a perineal bulging with increases in abdominal pressure (especially during coughing, straining, or a Valsalva maneuver). This perineal hernia develops because a large portion of the pelvic floor has been removed. If an extended resection (extralevator abdominoperineal or exenteration) is performed, the defect can be particularly large, allowing the small bowel to descend into and through the pelvis. Although postoperative perineal hernias are common, they are usually asymptomatic. Symptoms that occur vary from a painless but noticeable perineal bulge to a painful bulge, bowel or urinary obstruction, and even an ischemic breakdown of the perineal skin. The incidence of hernias requiring repair has been estimated to be 1% to 7% of abdominoperineal resections and 10% of pelvic exenterations; however, the condition is under-reported, with fewer than 75 cases included in the literature. This chapter discusses evaluation, treatment, and prevention of perineal hernias.
Repair of a perineal hernia is a major surgical procedure and should be reserved for symptomatic patients who are reasonable operative candidates. Patients are evaluated preoperatively for operative risks and to exclude the possibility of recurrent cancer. The evaluation includes a complete history and physical examination, routine blood studies, contrast radiology or endoscopy of the intestine and urinary tract, and computed tomography or magnetic resonance imaging scans of the abdomen and pelvis. Upright anteroposterior and lateral films of the pelvis during a small bowel follow-through study demonstrate loops of small bowel herniating into the pelvis.
As with all procedures, the potential benefits of symptom relief must be balanced against the risks of surgery. A history of pelvic irradiation increases the potential risks of hernia repair.
Patients undergo limited oral mechanical bowel preparation (e.g., with use of polyethylene glycol) and receive systemic prophylactic intravenous antibiotics. Patients also receive venous thromboembolic prophylaxis, as well as multimodality pain management.
The hernia can be repaired via either an abdominal or perineal approach, using primary repair, mesh (synthetic or biologic), or flaps.
The patient is positioned in a modified Lloyd-Davies position, which allows access to the perineum if a combined approach is required and room for a second assistant to provide retraction in the pelvis. In addition, this position allows easy preoperative placement of ureteric stents. The pelvis is explored through a lower midline incision. If no recurrent tumor is present, the loops of small bowel in the hernia sac ( Fig. 33-1, A ) are freed of their adhesions by lysis. Care is taken to identify and protect the ureters.