PARASTOMAL HERNIAS
By Julia Thompson RN Dip Ned BA (Psych) Grad Dip
(Adv Clin Nsg) FCN (NSW) Sigma Theta Tau
CNC Stomal Therapy. Westmead Hospital NSW and
Lesley Jack RN RM CNS
Stomal Therapy. Westmead Hospital NSW

ABSTRACT
Parastomal hernia occurs when intestine protrudes through the fascial defect around a stoma and into the subcutaneous tissue. This paper looks at the literature in relation to factors contributing to hernia development, the incidence, the effects and the common treatments for parastomal hernias.

INTRODUCTION
Herniation around a stoma is the commonest late complication of enterostome. (11) In 1980 Hughes referred to this as "an unsolved stoma problem", and we propose that it remains an unsolved problem in 1994. This paper will review some of the established facts and raise some of the still-unanswered questions.

Our interest in hernias arose from our contact with several patients whose hernias were causing them considerable concern and affecting their quality of life. Either our conservative measures had failed, or the patients were unwilling to try them because they were so adamant that they wanted the hernia surgically removed. Yet the surgeons were reluctant to operate because they believed that the chances of success were low.

Of the 594 new stomas created at Westmead Hospital between February 1990 and December 1993, there were approximately equal numbers of colostomies and ileostomies, but far fewer urinary stomas. In all, 29 stomas required attention for parastomal hernias: 20 colostomies (one transverse loop, 19 end colostomies), seven loop ileostomies, one ileal conduit and one colonic conduit. This may not seem many, but these were only the people who actually returned for help; we do not know the real incidence.

A parastomal hernia is caused by a gap between the intestinal segment forming the stoma and the surrounding tissue (Fig 1). The bowel protrudes through the defect in the fascia, resulting in a bulge at the base of the stoma. It may be partially or fully circumferential. If the opening is small the hernia is limited (parastomal), but often all the tissue surrounding the stoma thins out (peristomal). (13) The protrusion is accentuated when intra-abdominal pressure rises (e.g. during coughing or sneezing. It may be reducible (e.g. when the individual lies down); however, sometimes it is not.

FACTORS CONTRIBUTING TO PARASTOMAL HERNIA DEVELOPMENT
The development of parastomal hernias is multifactorial. One assumes that a major factor must be the 'weakness' (hole) in the abdominal wall. However, although every ostomate has this hole, they do not all develop a noticeable hernia. Since this is a specialised form of incisional hernia, it is precipitated by the same factors which lead to other types of incisional hernias. These include chronic cough, obesity, malnutrition, disorders of the urinary system and anything else which causes increased intra-abdominal pressure.

Some technical factors in stoma construction are believed to predispose the patient to hernia development. These include making the stoma in the main incision; (6) making the opening in the muscle too large, and not bringing the stoma through the rectus abdominus muscle. Sjodahl, Anderberg and Bolin (11) found stomas through the rectus had a 2.9% incidence of hernias but those lateral to the rectus had a 21.6% incidence. This highly significant difference (p=0.0004, Chi squared test) indicates that enterostomy should be constructed through the rectus obdominus muscle, not lateral to it. They also investigated the different incidence between ileostomy (2.2%) and sigmoidostomy (8.9%) and found that it was not statistically significant. However, others have made much of this difference in incidence between stoma types.

Hulten (6) proposed that it was due to the difference age groups having colostomy as compared with ileostomy surgery. However, Oritiz et al (7) took biopsies of rectus muscle at laparotomy and performed morphometric studies which demonstrated no significant difference between the two age groups (43.5 + 17.5 years and 64.8 + 12.9 years). They concluded that weakness of muscle wall due to increased age does not explain the difference in prevalence of parastomal hernias between colostomy and ileostomy.

INCIDENCE
The condition is certainly common, and increases with time after surgery. Most occur during the first 2 years after stoma formation, but some arise during the same hospitalisation in which the stoma was constructed. (8) The reported incidence of the problem varies greatly for several reasons. Many studies do not specify the length of follow-up, so this confuses the issue. (9) Another confounding aspect is that some studies only count those hernias which need treatment, whereas others include all (von Smitten et al, 1986). There are also variations according to type of enterostomy. Pearl (8) gives a table which illustrates the variation in reported incidences. Goligher (1984) proposed that "a colostomy is an unnatural protrusion through the abdominal wall and some degree of herniation may be inevitable."

Other estimates of incidence vary from 1-50%, but Pearl (8) puts 10% as a realistic estimate, noting that only 10-20% of these need repair. According to Hughes (5) and Winkler (13) the incidence is higher in loop colostomies, which they note are often temporary or palliative. The incidence seems to be lower following ileostomy and urinary diversion, with Hulten (6) and Ortiz et al (7) reporting 3-10% and Devlin (1983) reporting 5-10%.

Parastomal hernia is obviously a common problem. But how big a problem is it? This depends on the size of the hernia, on the individual who has it and on how that person interprets their situation.

EFFECTS OF PARASTOMAL HERNIAS
A parastomal hernia may cause a range of psychological and physical symptoms. To the onlooker it may just be a 'lump', and 'unsightly bulge'. To the nurse or doctor it represents a protrusion through a weakened muscle. But to the individual concerned, its appearance may evoke their worst fears…of a recurrence of their disease! Or it may be an embarrassment, causing them to retreat from normal social activities.

CASE A : Annie, a 72-year-old woman, underwent extensive surgery for ovarian cancer. She was repulsed by the sight of her open wounds and stoma, and covered her head with her nightgown whenever they were dressed. Eventually she watched the stoma care. Weeks passed before she was fit to walk, and when she finally stood in the bathroom and looked at her abdomen to learn to participate in stoma care, she was devastated by what she saw…a lump - the very thing that had caused her to go to the doctor in the first place!

CASE B : Katie, a 50-year-old woman, had a temporary sigmoid colostomy to divert faeces from a repaired recto-vaginal fistula. She had a history of obesity, had lost approximately 30kgs some years prior to the ostomy surgery and was desperate not to regain weight. She developed a moderate-sized parastomal hernia about 2 months post-operatively. About the time she was due to return to work someone, believing her to be pregnant, asked her when the baby was due. She was so embarrassed and upset that she refused to return to work or even to socialise with her friends until the stoma was closed some 14 months after the original surgery, and would not give permission for a photograph to be taken.

Other effects include instability of the abdominal wall and a strange feeling, "as if everything is falling out." This can later give way to abdominal aching and discomfort, and even intermittent intestinal obstruction. Strangulation of the contents of the hernia may necessitate bowel resection, (3,4) although Winkler (13) comments that this is uncommon in large peristomal hernias because the sac is so large.

Difficulty may arise during defecation. Appliances may not fit properly due to the altered contour. Because the contents of the hernial sac protrude when the person stands, but then recede when they are recumbent, this causes the skin alternately stretch and relax, disrupting the seal on the appliance and leading to leakages and excoriation. This problem is worse in those with ileostomies and urostomies because of the nature of the effluent.

Interestingly, there are occasions when stomas are easier to manage after a hernia occurs because it corrects a previous indentation which hindered appliance fixation.

When irrigating is the usual method of colostomy management there may be poor return, thought to be due to a siphon effect, as described by Winkler (13).

DESCRIPTION OF THE HERNIA
The hernial sac is lined with peritoneum and covered by a thin layer of scar tissue. As the protrusion increases, the subcutaneous fat thins out so that finally only a delicate covering is left. In extreme cases pressure ulceration may perforate, resulting in a fistula. The hernial sac may contain loops of small bowel, omentum, prestomal loops of colon and even transverse colon. The sac may become very large to strangulation is less likely, but the muscular defect may remain relatively small, in which case, theoretically, the possibility for surgical correction is good. (2)

EXTERNALLY
The hernia starts as a low, round protrusion, usually with the stoma in the middle. But in the course of time, with enlargement and loosening of the skin, the sac descends and the stoma may be difficult for the individual to see. This can also make appliance management difficult. A hernia may be complicated by loosening of the mesenteric pedicle and lengthening of the mesentery within the peritoneal cavity, which gives rise to prolapse. Loop ostomies are more likely to be affected, but end ostomies may also have this complication.

TREATMENT
Many people do not seek treatment if the hernia is small, and in people with a temporary stoma it is self-limiting because the defect will be repaired during stoma closure.

Tretbar (12) comments that in the older age group, who tend to have more weight in their abdomen, there are advantages in resiting a stoma above the umbilicus, where the rectus muscle is usually thicker and stronger than below the umbilicus, the there is less transmitted pressure to stretch the tissues through which the stoma protrudes.

Although local repair sounds easier because there is no need for a laparotomy, the procedure may be technically difficult, requiring wide undermining and careful dissection which sometimes leads to post-operative fluid collections and secondary infections, particularly when prosthetic mesh is used.(5)

A technique for hernia repair using Marlex mesh is outlined by Rosin and Bonardi, (10) and also successfully used and reported on by Abdu.(1) An eliptical incision dissects the colostomy from the skin and down through subcutaneous tissue to the fascia. The hernial sac is opened and the stoma clamped to avoid spillage. The hernial sac is dissected free, opened and reduced. The peritoneum is closed with chromic catgut. The fascia is approximated with interrupted, non-absorbably sutures. Redundant colon is removed. Marlex is tailored to cover the area of the hernia and dissection, with the end of the colon passing through a hole in the Marlex. The Marlex is sutured to the fascia. The wound is irrigated and a drain inserted before closure of the subcutaneous tissues and skin. The stoma is refashioned. Dry dressings are applied for 24 hours then an appliance is fitted. Antibiotics are administered for 3 days, then the haemovac is removed. Attention to aseptic technique is critical, since infection in Marlex is devastating.

Bayer, Kyzer and Chaimoff (2) propose a technique whereby the colostomy is strengthened with Marlex (polypropylene) mesh at the time of the original operation, in order to prevent subsequent herniation. In their technique, a ring of Marlex with four crosswise prolongations is sutured to the fascia. They reported a series of 43 persons, with no hernia or prolapse up to 4 years later.

CONCLUSION
This paper has presented some ideas about the development, incidence, effects and treatment of parastomal hernias. But there are still unanswered questions. What is the actual incidence? Apart from pre-operative siting and good surgical technique, are there any other measures a surgeon can take to reduce the incidence of hernias? Should stomal therapists be encouraging more people to wear support binders or corsets as a preventive measure? Should corsets have a hole in them for the appliance, or is this merely mimicking the original problem? Are there other conservative measures available?

Because parastomal hernias are common and have the potential to severely reduce quality of life, they are a subject worthy of careful consideration by those caring for persons with a stoma.

Reference
1. Abdu RA (1982) Repair of paracolostomy hernia with Marlex mesh,
DisColon Rectum 25:529-531.

2. Bayer I, Kyzer S and Chaimoff C (1986) A new approach to Primary strengthening of colostomy with Marlex mesh to Prevent paracolostomy hernia,
Surgery, Gynaecology and Obstetrics 163: 579-580

3. Cuthbertson A, Collins J (1977) Strangulated para-ileostomy Hernia,
Aust NZJ Surg 47: 86-87.

4. Daniell S (1981) Strangulated small bowel hernia with a Prolapsed colostomy stoma,
JR Soc Med 74: 687-688.

5. Hughes E (1980) Unsolved stoma problems, Paper presented at the 10th annual conference of the Australian Association Of Stomal Therapy Nurses, Perth 28-3-80.

6. Hulten L (1984) Prevention and management of paracolostomy hernia, Paper presented at the conference of the World Congress of Enterostomal Therapists, South Africa.

7. Ortiz H, Gracia F, Sara M, de Miguel M, Garrido J and Perez I (1991) Is colostomy hernia related to age?
Journal of the World Council of Enterostomal Therapists 11 (2): 19.

8. Pearl RK (1989) Parastomal hernias,
World Journal of Surgery 13: 569-572.

9. Porter JA, Salvati EP, Rubin RJ, Eisenstat TE (1989) Complications of colostomies.
Dis Colon Rectum 32 (44): 299-302.

10. Rosin JD and Bonardi RA (1977) Paracolostomy hernia repair with Marlex mesh.
Dis Colon Rectum 20 (4): 299-302.

11. Sjodahl R, Anderberg B and Bolin T (1988) Parastomal hernia in relation to site of the abdominal wall,
Br J Surg 75: 339-341.

12. Tretbar LL (1988) Insoluble stomal complications: the need For surgical revision, Conference Proceedings from the WCET Congress, Norway.

13. Winkler R. (1986) Stoma Therapy: An Atlas and Guide for Intestinal Stomas.
Georg Thieme Verlag Stuttgart, New York: 55.

Further reading
Doberneck Rc (1991) Revision and closure of the colostomy, Surg Clin North Am 7(1):193.

Ortiz H, Sara M, de Miguel M, Marti J, Petri M, Lopez E and Tegido M (1993) Does the frequency of Colostomy hernia depend on the colostomy location in the Abdominal wall? Journal of the World Council of Enterostomal Therapists 13(2): 13-14.

Santora TA, Roslyn JM (1993) Incisional Hernia,
Surg Clin North Am 73(3):557-570.