A condition known as diversion colitis frequently develops in segments of the colorectum after surgical diversion of the fecal stream; it persists indefinitely unless the excluded segment is reanastomosed. The disease is characterized by bleeding from inflamed colonic mucosa that mimics the bleeding of idiopathic inflammatory bowel disease, and it may culminate in stricture formation. We hypothesized that this condition is caused by the absence of luminal short-chain fatty acids, the preferred metabolic substrates of colonic epithelium. We studied four patients with diversion colitis, none of whom had evidence of Crohn's, idiopathic ulcerative, or infectious colitis. The excluded segment of the rectosigmoid contained negligible concentrations of short-chain fatty acids. When D-glucose was instilled, it did not undergo appreciable anaerobic fermentation. Instillation of a solution containing short-chain fatty acids twice daily resulted in the disappearance of symptoms and the inflammatory changes observed at endoscopy, over a period of four to six weeks. Remission has been maintained for up to 14 months (in one patient) by instillation daily to twice weekly. Administering enemas containing isotonic saline, or omitting treatment for periods of two to four weeks during the regimen, by contrast, did not produce any improvement or rapid relapse of the colitis. Histologic observation revealed a distinctive type of mucosal inflammation that resolved more slowly and less completely than the gross appearance of the inflamed mucosa. From these preliminary studies we infer that diversion colitis may represent an inflammatory state resulting from a nutritional deficiency in the lumen of the colonic epithelium, which is effectively treated by local application of short-chain fatty acids, the missing nutrients.

Treatment of Diversion Colitis with Short-Chain-Fatty Acid Irrigation

https://www.gastrojournal.org/article/S0016-5085(04)00461-5/pdf

From symptom to diagnosis: clinical distinctions among various forms of intestinal inflammation

Short-chain fatty acids (SCFAs), mainly acetate, propionate, and butyrate, produced by microbial fermentation of undigested food substances are believed to play a beneficial role in human gut health. Short-chain fatty acids influence colonic health through various mechanisms. In vitro and ex vivo studies show that SCFAs have anti-inflammatory and anticarcinogenic effects, play an important role in maintaining metabolic homeostasis in colonocytes, and protect colonocytes from external harm. Animal studies have found substantial positive effects of SCFAs or dietary fiber on colonic disease, but convincing evidence in humans is lacking. Most human intervention trials have been conducted in the context of inflammatory bowel disease. Only a limited number of those trials are of high quality, showing little or no favorable effect of SCFA treatment over placebo. Opportunities for future research include exploring the use of combination therapies with anti-inflammatory drugs, prebiotics, or probiotics; the use of prodrugs in the setting of carcinogenesis; or the direct application of SCFAs to improve mucosal healing after colonic surgery.

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Role of short-chain fatty acids in colonic inflammation, carcinogenesis, and mucosal protection and healing.

This review summarizes some of the common diagnostic problems encountered by pathologists when evaluating patients with chronic colitis and in whom inflammatory bowel disease (IBD) is either suspected or within the differential diagnosis. Both ulcerative colitis (UC) and Crohn's disease (CD) show characteristic, but non-specific, pathological features that may overlap and result in a diagnosis of 'indeterminate colitis' (IC). However, other reasons why pathologists may entertain a diagnosis of IC include failure to recognize or accept certain 'hardcore' histological features as indicative of CD, an attempt to classify cases of chronic colitis based on mucosal biopsy material or in the absence of adequate clinical and radiographic information, and the presence of other disease processes that mask, or mimic, IBD. In addition, some cases of UC may show unusual CD-like features, such as discontinuous or patchy disease, ileal inflammation, extracolonic inflammation, granulomatous inflammation in response to ruptured crypts, aphthous ulcers, or transmural inflammation. Furthermore, other forms of colitis, such as microscopic colitis, diverticulitis and diversion colitis may, on occasion, also show IBD-like changes. The clinical and pathological features that aid in the distinction between these entities, and others, are covered in detail in this review.

Diagnostic difficulties in inflammatory bowel disease pathology.

When all of the macroscopic and microscopic features of Crohn's disease and ulcerative colitis are present, the correct diagnosis is usually made without difficulty. When some of the changes are absent, the accuracy of diagnosis is reduced. This review has outlined those diseases which feature some of these pathological changes and may masquerade as idiopathic chronic inflammatory bowel disease. Some of the pathological mimics are iatrogenic while other common diseases, such as bacterial infection, ischaemia, and diverticulosis may produce confusing histological appearances. The picture is complicated by the fact that many of these pathological imitators may themselves cause or predispose to chronic inflammatory bowel disease, or may complicate chronic inflammatory bowel disease. For example, drugs and infectious agents are recognisable causes of relapse in ulcerative colitis; Crohn's disease may cause diverticulitis in patients with diverticulosis; and lymphoma may complicate ulcerative colitis. It behooves all practising histopathologists to recognise these mimics of ulcerative colitis and Crohn's disease to ensure appropriate management for patients with inflammatory pathology of the intestines.

https://jcp.bmj.com/content/jclinpath/44/9/726.full.pdf

Pathological mimics of chronic inflammatory bowel disease.

Diverting the fecal stream has been considered to benefit the course of Crohn's disease. Clinical signs and symptoms have not, however, been distinguished previously from the objective inflammatory changes in the distal segment. We reviewed the course of 16 consecutive patients with Crohn's disease in whom sigmoidoscopy showed normal mucosa at the time of diversion and who underwent an ileostomy or colostomy, the rectal segment being left in place. As early as 3 months after diversion, all 16 patients showed progressive friability, ulceration, and exudation in the retained rectum. Stricture occurred in four and lead to abdominoperineal resection in three. Four of eight patients with only moderate inflammation on sigmoidoscopy underwent reanastomosis which was followed by a return to a normal-appearing rectal mucosa. The rectal segment inflammed after diversion rarely shows the histological characteristics of Crohn's disease when resected. This leads us to suspect that the disorder of nonspecific "diversion colitis" might account for this phenomenon entirely, or at least it may accelerate the Crohn's disease process. Continuity of the intestinal tract should be maintained in the course of Crohn's disease surgery if feasible. If a diversion is clinically warranted, reanastomosis should be considered as early as possible despite progressive inflammation of the rectal mucosa.

The fate of the rectal segment after diversion of the fecal stream in Crohn's disease: its implications for surgical management.

https://www.gastrojournal.org/article/0016-5085(84)90547-X/pdf

Sheldon C. Sommers

Papers

The fate of the rectal segment after diversion of the fecal stream in Crohn's disease: its implications for surgical management.

Proctitis after fecal diversion in Crohn's disease and its elimination with reanastomosis: implications for surgical management. Report of four cases