Use of these criteria may serve as an aid to diagnosis and should ensure standardized entry criteria in clinical trials. It is therefore not surprising that organic disease may coexist in some. Although the criteria are not those of colon cancer, in an older patient the wise physician will exclude this at an early stage. This finding is pathognomonic of the chronic use of anthracene laxatives, such as senna, cascara or danthron. Cessation of the drug is followed in about six months by disappearance of the pigment.
Collagenous colitis is featured by chronic, watery diarrhea.
The mucosa in this condition appears normal at sigmoidoscopy and the thickened collagen plate can only be seen by microscopy. Collagenous colitis is not found in IBS when diagnosed by strict criteria so colorectal biopsy is not indicated. Of course IBS and constipation have no histologic features. A phosphate enema or other rectal application may cause transient mucosal abrasions and microscopic loss of epithelium with some polymorphonuclear reaction. The persistent pain and inattention to symptom details can lead to inappropriate surgery.