Parastomal Herniae

Raj Kapaia

Powerpoint File

“Some degree of herniation around a colostomy is so common that this complication may be regarded as inevitable” Goligher (1984)

Parastomal hernia is an incisional hernia related to an abdominal wall stoma, and its management is a common clinical dilemma. Once established it is difficult to treat. Many operative factors have been claimed to influence its occurrence and numerous techniques of repair have been described, testament to the problems with this condition.

Clinical diagnosis involves examination with the patient standing, lying and performing a valsalva manoeuvre, after removal of the appliance. Digital examination of the stoma allows assessment of the fascial aperture and the parastomal tissues. If the hernia cannot be demonstrated, CT may be necessary.

Devlin classified parastomal herniae into four types: interstitial, where the hernial sac lies within the layers of the abdominal wall; subcutaneous, where the sac lies in the subcutaneous plane; intrastomal, where the sac penetrates into a spout ileostomy; peristomal (prolapse), where the sac is within a prolapsing stoma. This system of classification is, however, not in common use, though it does allow a specific description of any hernia detected by CT.

Most parastomal herniae are asymptomatic. They may, on the other hand, produce symptoms ranging from mild parastomal discomfort to life- threatening complications, such as strangulation, perforation and obstruction. They may contain omentum, small bowel, stomach and colon. Many patients have parastomal discomfort or pain, intermittent obstructive episodes and difficulty with appliance application that may result in skin irritation, especially with an ileostomy. Psychological problems due to inability to conceal the stoma may also arise.

The range of incidence is wide and depends on the intensity and duration of follow-up, and the use of imaging. The majority of parastomal herniae seem to occur within the first 2 years of formation, though the risk does extend for life, and crudely seem to occur in 20-30% of stomas. However, the rate of occurrence seems to vary with the type of stoma. Ileal conduits have an incidence of 6-10%; otherwise the incidence varies with the type of stoma, colostomies having a higher rate (4-48%) to ileostomies (2-28%).

The risk factors for the development of parastomal herniae can be divided into intrinsic and extrinsic factors. Intrinsic factors include, age, obesity, wound infection and smoking. Extrinsic factors include emergency surgery, location of stoma and previous hernia repair.

The site of formation of the stoma on the anterior abdominal wall has long been thought to influence the incidence of parastomal herniae, however this is not borne out in what studies are available. Similarly, the size of the initial opening in the abdominal wall was felt to influence its formation. It has been suggested that a one finger aperture is suitable for an end ileostomy and two fingers for a loop ileostomy, with similar recommendations for colostomies. Others have been more precise, recommending 1.5-2cm openings for stomas. However there has never been a consensus. Additionally, it appears that herniation still occurs despite these recommendations. More recently it has been suggested that mesh be placed around the stoma at the time of its formation in an attempt to prevent enlargement of the fascial aperture. There are no data as yet to show if this will reduce the rate of hernia formation. Currently the best advice would be to use the smallest opening compatible with the creation of a viable stoma.

The best treatment for a parastomal hernia is to restore continuity of the intestine, thus removing the stoma. Clearly this is not feasible in the case of a permanent stoma. Most herniae are managed conservatively, with or without the use of a stomal supporting device; intervention being reserved for strangulation or obstruction and also where there is difficulty with the appliance. Parastomal pain and cosmesis are also relative indications for repair. In addition if the stoma is going to be revised, any associated hernia should be repaired at the same time.

The surgical options are many, but the literature suggests that the results are less than satisfactory. The surgical options fall into three categories: (a) stoma relocation; (b) local tissue repair and (c) either intraperitoneal, extraperitoneal or a fascial onlay of a prosthesis.

(a) Stoma Relocation This may be achieved with or without formal laparotomy. This is particularly useful if the stoma site is not ideal, as can occur if the stoma was a consequence of emergency surgery. Sites for relocation may be limited, however, if the patient has had multiple operations. Unfortunately, published series would appear to demonstrate that further herniation is the same as for that after primary stoma formation. There is a small amount of evidence that relocation with the addition of mesh support is associated with a lower incidence of recurrent parastomal herniation.

(b) Local Tissue Repair The technical simplicity of local tissue repair makes this an attractive option. Repair can be effected by suture of the musculoaponeurotic tissues of the fascial aperture. The overall results are poor, with recurrence rates of 46-100%. Though the numbers in most series are small, one has to accept that this technique in isolation is more likely to fail than not.

(c) Prosthesis Repair The use of prosthetic mesh in the repair of other herniae has prompted its use in parastomal herniae. Rosin and Bonardi were the first to describe the use of a facial onlay of polyethylene mesh in 1977. Since then techniques for the placement of mesh intraperitoneally, and preperitoneally have been described, as has the use of laparoscopic approaches. The fascial onlay method involves mobilisation of the stoma at the mucocutaneous junction or at a distance from it, the latter theoretically having less risk of contamination. Again, most series are small, however there does appear to be a reduction in rates of recurrence.

Intraperitoneal placement, originally described by Sugarbaker in 1980, involves the placement of mesh at laparotomy. There were problems with adhesion formation to the mesh and subsequent intestinal obstruction. Consequently experience with this technique is limited. More recently, the introduction of less irritative meshes and laparoscopy has seen increasing use of this method for parastomal hernia repair. There are insufficient numbers to enable any conclusions to be drawn, though initial results look promising.

The placement of mesh in the plane between the posterior fascia/peritoneum and the rectus muscle has been described. Numbers are very small, presumably because of the difficulty in establishing the right plane. Unfortunately significant complications have been relatively common though recurrence rates are acceptable.

In conclusion, parastomal herniae occur frequently following stoma formation. Repair to date has given poor results, though with newer techniques these would appear to be improving. Studies in the prevention of herniation when stomas are formed are urgently required. Similarly, large, possibly multicentre, trials of parastomal hernia repair, using more modern techniques, are required to address this difficult clinical problem. Additionally the optimal time for repair has not been established.