Diversion colitis

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Diversion colitis is an inflammation of the colon which can occur as a complication of ileostomy or colostomy, often occurring within the year following the surgery. It also occurs frequently in a neovagina created by colovaginoplasty, with varying delay after the original procedure. Despite the presence of a variable degree of inflammation the most suggestive histological feature remains the prominent lymphoid aggregates. A foul smelling, mucous rectal discharge may develop from the inflamed mucosa of the distal, unused colon.

Normally, food is digested and absorbed by the time it reaches the end of the small intestine. The leftover residue that enters the large intestine (colon) is mainly liquid waste material. If your digestive tract is working normally, the waste becomes more solid (feces) as it passes through the large intestine. The waste is held in the rectum and eliminated through the anus.

Fecal diversion is done to re-route the waste, in order to treat some diseases in the large intestine. The healthy end of the large intestine—or in some cases, the small intestine—is attached to a surgical opening in the skin. The waste is eliminated through the small opening, called a colostomy. (If the end of the small intestine is attached to the skin, the opening is called a ileostomy.) The opening has no sphincter muscles. This means that you cannot control the flow of waste out of this opening. Instead, you wear a small pouch, called an ostomy bag, to collect the waste.

Diversion colitis develops in the part of the intestine that is no longer in use. Scientists do not know exactly why this happens. One factor is that the helpful bacteria that live in the colon do not get the “food” they need. These bacteria usually live on the undigested starches and fiber in normal waste. The parts they consume are called short-chain fatty acids. When the waste no longer passes through that part of the colon, some of these bacteria start to die.

CLINICAL FEATURES — Most patients with diversion colitis evident histologically are asymptomatic. However, the likelihood of symptoms may at least in part be related to the underlying disease. In a study of 36 children with Hirschsprung’s disease, for example, only one child who maintained his ileostomy for six years developed rectal discharge. After restoration of intestinal continuity, he and the other 35 children had no symptoms for up to nine years of follow-up .

By contrast, children diverted because of severe motility disorders may develop abdominal pain and bleeding from the rectosigmoid colon. In an illustrative series, 3 of 18 children who had undergone colovaginoplasty two to seven years earlier developed neovaginal discharge and bleeding due to diversion colitis requiring treatment.

The most common symptoms in adults are rectal bleeding, tenesmus, mucus discharge, and abdominal pain. Symptoms are usually mild, and occur in 6 to 38 percent of patients. Infrequent findings include bleeding requiring transfusion, diarrhea, or sepsis from deep ulceration requiring proctectomy.

DIAGNOSIS — Diversion colitis should be considered in an individual with or without preexisting inflammatory bowel disease, who complains of cramping abdominal pain with a mucoid or bloody discharge coming from a defunctionalized, bypassed distal colon. The clinical onset may begin within a few months after surgery or after a long delay.

The diagnosis is based upon compatible clinical features and histologic findings and exclusion of other disorders that can produce similar clinical findings. These include acute self-limited colitis, C. difficile infection, and (in patients who have had the diversion performed because of ulcerative colitis or Crohn’s disease) preexisting inflammatory bowel disease. A response to short chain fatty acid therapy helps support the diagnosis.

TREATMENT — As noted above, most patients with surgical diversion of the fecal stream do not develop rectal symptoms that require investigation. In those with symptoms, restoration of intestinal continuity should be considered as early as possible after diversion since it is curative. Early reanastomosis is preferred because, with increasing delay after diversion, symptoms often become more frequent and severe and there is a progressive decrease in capacity and involution of the defunctionalized anorectum . Options for patients who are not candidates for reanastomosis are described below.

Short chain fatty acid enemas — The observation that diversion colitis results from a deficiency of short-chain fatty acids (SCFAs) provided the rationale for studies involving SCFA for treatment. Most studies have been small and observational and results have been mixed.

  • One prospective double-blind trial did not observe endoscopic or histologic remission with SCFA. However, only 1 of the 13 subjects had symptoms, most had only mild endoscopic changes, and the trial only lasted two weeks.
  • Another study demonstrated that short-term (3 week) SCFA instillation for three weeks did not control inflammation in patients with acute colitis (nine Crohn’s and one ulcerative colitis) who underwent colectomy with creation of a Hartmann pouch. Most patients had severe inflammation by endoscopy and histology more consistent with the underlying inflammatory process than with diversion colitis.
  • A clinical observation has been that children diverted for reasons other than inflammatory bowel disease seem to respond more consistently to SCFAs than adults. However, encouraging short-term results have been reported in a few children diverted for various types of colitis. Even in this group, the long-term response is unknown since most of these children had restoration of intestinal continuity within a few months after diversion.

The reports cited above are consistent with our observation that SCFAs work best for diversion colitis when the diverted segment was normal before the fecal stream was interrupted. On the other hand, we have seen two adults with Crohn’s colitis (both of whom presented with spontaneous sigmoid perforation) in whom SCFA rectal irrigation was associated with complete symptomatic response and marked histologic improvement. In those with preexisting inflammatory bowel disease, SCFAs combined with antiinflammatory drugs may be effective.

SCFA enemas are straightforward to prepare and are available at many compounding pharmacies.

  • The enema solution consists of sodium acetate (60 mmol), sodium propionate (30 mmol) and sodium n-butyrate (40 mmol) with additional sodium chloride (22 mmol) to yield an osmolality of 280 to 290 mosmol/L which is similar to plasma. The pH is adjusted to 7.0 with sodium hydroxide.
  • A dose of 60 mL should be instilled into the rectum twice daily for up to six weeks. Once improvement occurs, it can usually be maintained by a less frequent schedule.

5-aminosalicylic acid enemas — 5-aminosalicylic acid enemas have been beneficial in a case report . Such an approach may be best suited for patients who have underlying inflammatory bowel disease.

Experimental approaches — A pilot study from Brazil described a novel approach in eleven previously healthy young adults (ages 16 to 49) who had undergone loop colostomies because of abdominal trauma. Patients were instructed to irrigate the distal limb twice daily (via the colostomy) with a commercial fiber solution. Endoscopic scores improved significantly in the distal segment close to the irrigation site and the rectum. Crypt depth also improved close to the irrigation site but not in the rectum. If confirmed, these observations lend support to the nutritional hypothesis for diversion colitis and suggest a possible new means for intervention, at least in those with loop colostomies.

Cancer surveillance — Surveillance for cancer in the diverted segment is not necessary unless the underlying condition for which the operation was performed has malignant predisposition for which screening is useful.

Prophylaxis — There are no studies evaluating the benefit of prophylactic treatment to prevent diversion colitis.

Crohn’s disease — Diversion performed in a patient with Crohn’s disease demands special consideration. Clinical experience has shown that, if the distal segment was not involved clinically before diversion, early reanastomosis will improve symptoms that develop from that segment after surgery and may help avert stricture formation.

In the unusual patient with known distal colonic Crohn’s who develops rectal symptoms after diversion, a positive response to SCFA enemas supports the diagnosis of active diversion colitis and should encourage reanastomosis.

SUMMARY AND RECOMMENDATIONS

  • Diversion colitis is an inflammatory process that occurs in segments of the colorectum that are diverted from the fecal stream by surgery.
  • Diversion colitis is an inflammatory state that probably results from a deficiency of short-chain fatty acids (SCFAs), the preferred luminal nutrients for colonocytes, in the diverted segment.
  • Most patients with diversion colitis evident histologically are asymptomatic. When symptoms are present they are generally mild and can include rectal bleeding, tenesmus, mucus discharge, and abdominal pain.
  • Diversion colitis should be considered in an individual with or without preexisting inflammatory bowel disease, who complains of cramping abdominal pain with a mucoid or bloody discharge coming from a defunctionalized, bypassed distal colon. The clinical onset may begin within a few months after surgery or after a long delay. The diagnosis is based upon compatible clinical features and histologic findings and exclusion of other disorders that can produce similar clinical findings.
  • In patients with symptomatic diversion colitis in whom restoration of intestinal continuity is feasible, we suggest reanastomosis as soon as possible after diversion (Grade 2C).
  • In symptomatic patients who are not candidates for reanastomosis, we suggest a trial of short chain fatty acid enemas (Grade 2B). As a general rule, they tend to work best for patients in whom the diverted segment was normal before the fecal stream was interrupted. Short chain fatty acid enemas have to be compounded and thus they are available only in pharmacies with compounding capabilities.
  • In patients who do not respond, we suggest the addition and/or substitution with 5-ASA enemas (Grade 2C). Such an approach may be best suited for patients with underlying inflammatory bowel disease in whom it can be difficult to confidently distinguish between the contribution of underlying IBD versus diversion colitis to the clinical features.
  • Diversion performed in a patient with Crohn’s disease demands special consideration. Clinical experience has shown that, if the distal segment was not involved clinically before diversion, early reanastomosis will improve symptoms that develop from that segment after surgery and may help avert stricture formation. In the unusual patient with known distal colonic Crohn’s who develops rectal symptoms after diversion, a positive response to SCFA enemas supports the diagnosis of active diversion colitis and encourages reanastomosis.

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