These depend upon the site affected. There are three typical patterns. Small bowel disease usually affects the ileocaecal segment. The patient presents with colicky abdominal pain, diarrhoea, and weight loss (see Section 18.2.4) 129. Colonic disease may present as colitis with bloody diarrhoea, urgency, and frequency, similar to that of ulcerative colitis. Discontinuous disease with fibrosis and stenosis may, however, cause diarrhoea without bleeding or colonic obstructive symptoms. Fistulation to adjacent organs may give rise to the distinct clinical feature of a colovesical or rectovaginal fistula. Ileocolic fistula between the ileum and the sigmoid colon is usually due to ileal disease. Colonic disease is secondary and may cause an increase in diarrhoea or no symptoms at all. Perianal disease is a particular feature of Crohn's disease: a chronic anal fissure may be the first presenting symptom.

Barium enema may show areas of discontinuous disease. In patients with stricture (Fig. 1) 1056, in whom the diagnosis may be in doubt, a colonoscopy will show mucosal changes, and information from multiple biopsies will allow the exact distribution of disease to be documented (Fig. 2) 1057,1058. Colonic stricture should be carefully investigated since it may indicate occult malignancy. Blood tests, including measurement of ESR or viscosity and C-reactive protein levels will give an indication of disease activity. Serum albumin levels indicate nutritional status.

There are two clinical pictures which must be distinguished in the management of colonic Crohn's disease. Administration of steroids, and occasionally azathioprine, is appropriate treatment for disease flares, which give rise to mucosal ulceration and oedema. This treatment is similar to that used for ulcerative colitis. Fibrosis and thickening, with obstruction or formation of a fistula and an abscess often requires surgical treatment, however. Before surgery is undertaken nutritional status must be assessed. Patients with extensive gut disease or sepsis may be severely nutritionally depleted: serum albumin level and weight loss history are a rough guide to the degree of the nutritional problem. Intravenous nutrition or, in some suitable cases, nasoenteric feeding may be necessary.

As with small intestinal disease, the management of Crohn's disease of the colon is medical unless a specific complication is present (Table 1) 330.

Although Crohn's disease of the colon may behave like ulcerative colitis, surgical treatment is different in a number of respects.

The usual indication is acute fulminating Crohn's colitis with bleeding, toxic dilatation, or perforation. It is important to note that the perforation can occur without toxic dilatation. The procedure of choice is usually a subtotal colectomy with formation of an end ileostomy. A mucous fistula may be constructed initially if there is relative rectal sparing. Oversewing of the rectal stump at the level of the peritoneal reflection is advised only if the rectum is normal, since in the presence of active Crohn's disease there is the risk of breakdown and intra-abdominal sepsis. The formation of a mucus fistula also has the advantage of allowing topical steroid irrigation of the defunctioned distal rectum.

There is a limited place for primary resection and ileorectal anastomosis as an emergency procedure, for example in patients who are fit, in whom there is no pre-existing sepsis, and when the rectum is spared. If the operative field is contaminated, the risk of dehiscence, leakage, or fistula formation is high and it would be wise to employ a proximal loop ileostomy in these cases. The indications for a primary proctocolectomy in emergency situations are also limited. If there is severe bleeding from the rectum there may be no choice, but secondary rectal excision is best performed at a later date, when the patient's general condition has improved.

Use of an emergency defunctioning loop or split ileostomy should be considered. Defunctioning of diffuse or multiple site colonic disease may allow it to resolve, and in about one-third of patients gut continuity can be restored without resection. A loop ileostomy has the advantage that closure does not require a laparotomy, but the disadvantage that, unless constructed properly, overspill occurs and defunction of the distal bowel is not complete.

Following an emergency operation for Crohn's colitis the patient is usually left with a mucus fistula or oversewn rectal stump. Patients in whom restoration of intestinal continuity may be possible have to be carefully selected. An ileorectal anastomosis is only advised where there is rectal sparing, minimal small bowel disease, and quiescent anal disease. They must therefore be carefully investigated by a rectal examination, proctoscopy, and anal manometry. Continuing inflammation in the rectal stump can be due to defunction colitis as well as Crohn's disease, and this should be borne in mind when interpreting rectal biopsies.

In some patients with colonic Crohn's disease a single localized segment is affected, causing either a stricture, fistula, or abscess. It is reasonable to perform a limited resection with an immediate colocolonic anastomosis in these patients. This preserves macroscopically normal colonic tissue and may have a functional advantage in preserving colonic water handling. Allan et al. have reported their experience in 36 patients treated by segmental colectomy. The 10-year reoperative rate for recurrent disease was 66 per cent, compared with 53 per cent among patients undergoing subtotal colectomy and ileorectal anastomosis. There was no clinical evidence of an anastomotic leak in 29 patients, suggesting that the procedure can be safe.

This is indicated in patients with severe diffuse colonic disease and rectal sparing. It is particularly indicated in younger patients, since it allows them to complete their education, start a career, and begin a family without the risk of sexual dysfunction or the disability associated with a stoma and perianal wound. This operation is contraindicated if the anal sphincter has been damaged as a result of previous perianal surgery or severe perianal disease, or if the patient has extensive rectal disease. In the presence of extensive small bowel disease, recurrence rates after ileorectal anastomosis may be high.

The majority of patients have a good functional result with an ileorectal anastomosis, provided that the reservoir function of the rectum can be maximized by anastomosis at the rectosigmoid junction. The majority of patients will have less than six bowel actions a day and troublesome diarrhoea is unusual. The worst functional outcome is seen in patients who have obvious macroscopic disease of the rectum.

The major early complication is anastomotic dehiscence, which occurs in between 5 and 30 per cent of patients. A covering loop ileostomy may reduce the incidence of this complication, although if this is thought necessary it may not be wise to perform the ileorectal anastomosis at all. The operative mortality ranges from 0 to 5 per cent. Recurrence rates are shown in Table 2 331: these seem to be higher than those in similar patients undergoing proctocolectomy and ileostomy.

Recurrence of disease does not always mean that a proctocolectomy and ileostomy is inevitable. Recurrence at the ileorectal anastomosis can be dealt with medically or by a further resection and ileorectal anastomosis.

Total colectomy with formation of an end ileostomy and mucous fistula

Total colectomy with formation of an end ileostomy and a mucous fistula or oversewing of the rectal stump has the advantage of safety and reduces the risk of recurrence proximal to an anastomosis. The recurrence rates in the ileum and ileostomy are similar to those seen after a proctocolectomy. The main indication is as an emergency procedure for severe colitis, but subsequent restoration of continuity is often not possible. This operation can also be used for the treatment of severe proctitis or severe perianal disease in patients likely to suffer delayed perianal wound healing or persistent perineal sinus. Continuing sepsis in the perineum, however, often means that the rectal stump has to be removed later. Operative mortality is of the order of 8 per cent and recurrence proximal to the stoma in the ileum is 13 per cent over 10 years.

This is indicated for extensive colonic disease involving the rectum, with or without perianal disease. It is also indicated in patients with severe anorectal disease, even in the presence of an apparently normal upstream colon. Recurrence rates in the proximal colon and the problem of a liquid flush end colostomy are considerable. A permanent end ileostomy is therefore preferable.

The incidence of stomal dysfunction is high. Complications associated with the stoma include retraction, prolapse, fistula formation, and obstruction. Most of these can be managed by local revision, but in the presence of recurrent Crohn's disease, laparotomy and resection is often necessary.

There is a high incidence of delayed perianal wound healing with resulting long-term morbidity and a persistent perianal sinus. Healing rates are slower if the wound is left open than is the case in patients treated with suture and suction drainage. Healing rates range from 63 per cent by 12 weeks to 33 per cent by 6 months. If there is faecal contamination and the risk of sepsis is high, the perineal wound should be left open. Perianal wounds which show delayed or non-healing are associated with high fistula in ano, faecal contamination, and postoperative perineal wound infection.

Management should be conservative initially, but if after a few months the perineal wound is recurrently discharging or has exuberant granulation tissue around the sinus it should be explored. Primary causes of long-term failure to heal include a foreign body such as a stitch, a pilonidal sinus, hydradenitis, an enteroperineal fistula, retained rectal mucosa, and malignancy. A large number of procedures have been suggested, such as currettage, suture and excision, muscle grafting, and skin grafting; all are associated with a variable success rate.

A significant number of patients develop urinary and sexual dysfunction as a result of nerve injury and perineal fibrosis. The incidence can be reduced by a perimuscular excision of the rectum and an intersphincteric excision of the anus.

Proctocolectomy is associated with the lowest recurrence rate but it has an operative mortality of between 3 and 9 per cent. The postoperative stay in hospital is often long, while the patient learns to care for their stoma, and also due to delayed perineal wound healing. Recurrence rates following proctocolectomy are about half of those seen after restorative surgery (see Table 2 331). Recurrent disease is usually located in the distal ileum.

In a small proportion of patients with Crohn's disease only the rectum is involved, often associated with severe perianal disease. If the disease cannot be controlled medically a permanent end colostomy may be suitable for selected patients. Particular indications for this procedure include a high fistula or rectovaginal fistula, together with narrow anorectal strictures. Problems of perineal wound healing should be borne in mind, together with the difficulty in managing a liquid colostomy experienced by some patients.

Faecal diversion (loop ileostomy) has been advocated by the Oxford group as an alternative to conventional surgical management in the following circumstances.

1.To achieve colonic healing and allow intestinal continuity to be restored without resection where the disease is diffuse but not severe enough to warrant a proctocolectomy.

2.To facilitate major resection in those with poor health.

3.To limit resection in patients with diffuse disease.

4.To avoid growth retardation in children with diffuse colitis requiring colectomy.

5.To protect or avoid a primary anastomosis, and after small bowel resection in patients with persistent colonic disease.

6.In the management of refractory perianal disease as a means of delaying or even preventing proctocolectomy.

A limited number of patients are suitable for this form of management. The percentage of patients in whom intestinal continuity can be restored varies from over 60 per cent to less than 30 per cent, and relapse after restoration of continuity ranges from 28 to 60 per cent. Nevertheless, a proximal loop ileostomy is a relatively minor procedure and in the debilitated patient may buy time before definitive surgery is contemplated.

Over 50 per cent of patients with Crohn's disease have anal lesions; these are most common in those with rectal disease. Fissure in ano is the most common lesion and may be asymptomatic. Such a fissure can heal with medical management or may become chronic and the site of subsequent fistula formation, probably by distorting anal glands. These fissures are often painless, but if there is an associated submucosal or intersphincteric abscess pain is so severe that proximal defunction is necessary (Fig. 3a) 1059. Anal surgery for fissure should be avoided as far as possible. A fistula in ano may develop either directly as a result of Crohn's disease or secondary to its effect upon the anal gland anatomy; fistulae are sometimes multiple and complex (Fig. 3(b)) 1060. Associated abscesses have to be drained but every attempt should be made to conserve any sphincter muscle. The key note to management is to be conservative.

Since many of these fistulae are asymptomatic or only intermittently symptomatic, treatment with metronidazole, steroids, and occasionally azathioprine can have dramatic effects on control of progress of disease, provided that no undrained pus is present.

Proper assessment is difficult in the clinic and symptomatic patients should undergo an examination under anaesthesia. Fistula tracts are carefully probed and curretted; if associated abscesses cannot be drained without division of muscle a seton can be left in place, often for many weeks or months, to control symptoms. A long-term indwelling seton functioning as a drain can often prevent or delay the need for proctectomy. I usually use a 2-mm diameter coloured plastic vessel loop tied loosely rather than tightly (Fig. 4) 1061. If the disease is progressive or fails to respond to conservative management despite repeated examinations under anaesthesia it is worth considering a proximal diversion (see above). Proctectomy is necessary for the treatment of severe disease unresponsive to conservative therapy. Bear in mind that long-standing fistula in ano may undergo malignant change in patients with Crohn's disease.

These may be quiescent, but can be very troublesome (Fig. 5) 1062. Asymptomatic patients need no treatment, and low fistulae can be laid open. A chronic indwelling seton can be used for drainage, as for perianal fistula, and where there is no severe rectal disease or proximal disease, repair of a fistula by a vaginal flap can be successful. Patients with intractable disease and those developing incontinence require a proctectomy.

Great care must be taken in treating haemorrhoids in patients with Crohn's disease. A haemorrhoidectomy should be avoided as far as possible; symptoms will generally settle spontaneously or following local steroid applications (Table 3) 332.

Allan A, Andrews H, Hilton CJ, Keighley MRB, Allan RN, Alexander Williams J. Segmental colonic resection is an appropriate operation for short skip lesions due to Crohn's disease in the colon. World J Surg 1989; 13: 611–16.

Lee ECG. Surgery for Crohn's disease. Gut 1984; 25: 217.

Williams JG, Wong WD, Rothenberger DA, Goldberg SM. Recurrence of Crohn's disease after resection. Br J Surg 1991; 78: 10–19.