Diversion colitis involves inflammation in the large intestine brought on after surgical treatment that diverts the fecal stream away from the large intestine, usually to a temporary ileostomy or colostomy. It should not be confused with being a type of inflammatory bowel disease (IBD), even though it often mimics the symptoms of IBD. Diversion colitis can occur after surgical treatment for intestinal-related conditions such as fecal incontinence, bowel cancer, or spontaneous chronic constipation that is not related to an obvious underlying cause.1
What is diversion colitis?
Diversion colitis is the widespread and non-specific inflammation of a defunctioned colon (or defunctionalized bowel). If an individual undergoes a colectomy or ileostomy that diverts the fecal stream away from a portion of the colon, this unused portion becomes defunctioned. The defunctioned portion of the colon no longer carries fecal waste, but may not be removed from the body depending on the reason the diversion occurred in the first place, as well as the risk of completing the procedure. A large portion of individuals, as high as 91%, who have a defunctioned colon will develop diversion colitis, however, not all of these individuals will experience symptoms.2 Signs of diversion colitis can be found during an endoscopic exam or colonoscopy.3,4 Individuals who have the colon removed but who still have a rectum may experience a similar condition called diversion proctitis, where inflammation is found in the rectum, rather than the colon.5
What are the symptoms of diversion colitis?
Many individuals with diversion colitis will be asymptomatic, or experience no symptoms. However, some individuals may experience abdominal cramping or pain, bleeding or discharge from the rectum, and tenesmus.3,4Tenesmus refers to rectal cramping or pain that makes an individual feel as though they need to have a bowel movement even though the bowels are empty, or such as in the case of diversion colitis, the rectum is no longer attached to the bowels.
What causes diversion colitis?
It is thought that diversion colitis is a result of changes in the bacterial composition of the defunctioned section of the colon. Diversion colitis may also be due to a reduction in nutrients delivered to the cells that live in the defunctioned colon after fecal matter has stopped passing through. The deprivation of one nutrient specifically, short chain fatty acids, is thought to play a role in the development of diversion colitis.4,6,7
How is diversion colitis treated?
Diversion colitis is most often treated by reanastomosis, or the rejoining of the defunctioned bowel to the rest of the intestines.1 In most cases, this reconnecting of the intestines quickly does away with the inflammation and restores the colon to a healthy state. Diversion proctitis is also treated through reconnection of the rectum.5 It is very important for physicians to recognize the difference between diversion colitis and inflammatory bowel disease because the treatment options are vastly different. While the treatment option for diversion colitis is most often reconnection of the intestines, for those with inflammatory bowel disease, the best option would be to remove the diseased colon entirely.1
There are some cases where reconnection may not be a feasible or beneficial treatment option. In instances where this is not possible, there are other treatment options that can be pursued and may help improve symptoms. These options include, but are not limited to, enemas containing short chain fatty acids (also called short-chain fatty acid irrigation or short-chain fatty acid topical treatment) and enemas containing corticosteroids.4,6,7
As mentioned, not everyone with diversion colitis experiences symptoms, so some may go undiagnosed and therefore not undergo treatment. In some severe cases if diversion colitis is left untreated, it may lead to colonic stricture (the narrowing of a section of the intestines) or the complete loss of function of the defunctioned bowel. This means that even if the bowel was reconnected in the future, it may not ever regain its full function.7Additionally, some preliminary research has suggested that diversion colitis may act as a trigger for the flare or development of inflammatory bowel disease in the future, specifically ulcerative colitis, however, more research is needed to determine the exact relationship between these conditions.4 Recent studies have shown that diversion colitis may return in the years following reconnection, but these patients are most often asymptomatic and the inflammation is only detected through laboratory testing.6