Ventral hernias can occur after any abdominal incision. They are relatively common after open colorectal surgery, and patients with an abdominal stoma are particularly prone to the development of hernias. Patients with ventral hernias often present a complex surgical problem. In such patients, the effects of the prior surgeries combine with the difficulty of achieving a permanent repair of sometimes large or complex defects in the presence of significant comorbidities. Parastomal hernias in particular are a challenge for which no uniform approach has been defined. Specific areas of controversy include the choice of prosthetic material in the presence of contamination, its position relative to the layers of the abdominal wall, and its placement via open or laparoscopic techniques. The context of a patient with inflammatory bowel disease (IBD)—with the associated risk of a repeat operation—can further complicate matters. An important variable in the decision-making process of parastomal hernia repair is whether the stoma is permanent or temporary. In this chapter we seek to address these controversial topics and difficult procedures relating to abdominal hernia surgery.
Permanent Enterostomy—Parastomal Hernia Repair
A parastomal hernia is defined as an incisional hernia related to an abdominal wall stoma. Rates as high as 50% have been reported, and some consider it an inevitable complication after formation of an enterostomy. Computed tomography (CT) is the most sensitive method of detection, although any palpable bulge or defect adjacent to a stoma is sufficient for diagnosis. Several classification schemes have been proposed, but none has been universally accepted or has had a meaningful impact on decision making in clinical practice. Our preferred method of description is summarized in Table 95-1 .
|Subcutaneous||Hernia sac within subcutaneous tissue||Most common|
|Interstitial||Hernia sac within layers of abdominal wall||High strangulation risk|
|Peristomal||Hernia sac circumferentially encloses stoma|
|Intrastomal||Hernia sac between intestinal wall and everted intestine|
Although data are limited to retrospective comparative studies, it is widely accepted that forming an ostomy through the rectus abdominis muscle results in fewer parastomal hernias when compared with stomas situated lateral to rectus or those brought through the midline. Not surprisingly, a stoma aperture that is too large places the patient at increased risk for subsequent hernia formation. This association is supported by the relationship between bowel caliber and hernia incidence. For example, end colostomies have a parastomal hernia rate between 4% and 48% compared with that of end ileostomies, which have a range from 1.8% to 28.3%. Medical comorbidities such as obesity, wound infection, old age, steroid use, chronic respiratory disorders, and malnutrition also have been implicated as risk factors.
Some practitioners believe that parastomal hernias require no treatment at all, and repair rates range from 11% to 70%. Although small asymptomatic hernias detected by a CT scan can be managed nonoperatively, most will become symptomatic and require repair, particularly in the presence of a concurrent midline incisional hernia. Indications for surgery include obstruction, incarceration, prolapse, pain/discomfort, bleeding, or difficulty maintaining a seal with the stoma appliance, typically associated with large hernias.
Repair techniques can be performed in an open or laparoscopic manner, each of which has its own benefits and limitations. Although local revision with primary fascial repair is technically simple and avoids the use of a prosthetic or additional laparotomy, it is associated with recurrence rates of 46% to 100%. A more radical technique is stoma relocation, but this procedure requires an additional laparotomy and results in three potential hernia sites: the original stoma aperture, the repeat laparotomy incision, and the new stoma. Relocation has been associated with recurrence rates of 24% to 86% and overall complication rates as high as 88%. Regardless of the approach, primary repair without prosthetic reinforcement has been largely abandoned. In a large systematic review, Hansson et al concluded that direct repair has more recurrences and wound infection than when a repair is reinforced with a prosthetic. Although obstruction, fistulization, and mesh erosion are legitimate concerns, the use of prosthetic reinforcement for parastomal hernia repair appears to be safe, with a low overall rate of mesh infection or excision. Therefore, almost all parastomal hernias are currently repaired using prosthetic reinforcement placed via an open laparotomy or laparoscopically.
Open repair of a permanent ostomy can be performed using a number of techniques. Prosthetic material can be placed above the anterior rectus fascia (onlay), within the retrorectus space (sublay), or within the peritoneal cavity exposed to the viscera (underlay). The review by Hansson and colleagues demonstrated that the lowest recurrence rate occurred with sublay mesh placement (6.9%). Onlay mesh placement has lower wound morbidity (1.9%) but higher rates of mesh infection/excision (2.6%). The findings are summarized in Table 95-2 .
|COMPLICATIONS (95% CI)|
|Technique||No. Studies||No. Repairs||Wound Infection, % (95% CI)||Mesh Infection, % (95% CI)||Other, % (95% CI)||Recurrence, % ∗ (95% CI)|
|Suture repair||5||106||11.8 (6.1-20.2)||–||10.8 (5.3-18.9)||69.4 (59.7-78.3)|
|Onlay mesh||8||176||1.9 (0.4-5.5)||2.6 (0.7-6.4)||8.3 (4.5-13.7)||17.2 (11.9-23.4)|
|Sublay mesh||3||42||4.8 (0.6-16.2)||0 (0.0-8.4)||7.1 (1.5-19.5)||6.9 (1.1-17.2)|
|Sugarbaker||1||20||5.0 (0.1-24.9)||0 (0.0-16.8)||10.0 (1.2-31.7)||15.0 (3.2-37.9)|
|Keyhole||4||45||2.2 (0.0-11.8)||2.2 (0.0-11.8)||17.8 (8.0-32.1)||7.2 (1.7-16.0)|
|All laparoscopic mesh||12||338||3.3 (1.6-5.7)||2.7 (1.2-5.0)||12.7 (10.2-17.5)||14.2 (10.7-18.0)|