Frequency of Microscopic Colitis in Patients with Chronic Watery Diarrhea

Abstract

ABSTRACT

Background: Chronic watery diarrhea is a common cause for consulting a physician in internal medicine. Microscopic colitis now has emerged as a common cause of chronic watery diarrhea, its prevalence is not clearly known. Some patients have mild symptoms that may be misinterpreted as irritable bowel syndrome.  Grossly, microscopic colitis characterized by normal or almost normal colonic mucosa and diagnosed by microscopic examination of a biopsy or sample of colon tissue obtained during colonoscopy.

Objectives: To investigate the frequency of microscopic colitis in patients with chronic watery diarrhea and compared with patients with diagnosis of diarrhea predominant irritable bowel syndrome. 

Methods: Between January 2008 and January 2013, 138 patients, age range 20-78 years (53.5 ± 11.2) were recruited into the study prospectively who had undergoing colonoscopy in gastroenterology unite of Ramadi Teaching Hospital for indication of chronic watery non bloody diarrhea with no apparent cause. Eighty four patients with chronic idiopathic watery diarrhea and Fifty four patients were diagnosed as IBS using the Rome III criteria and had watery diarrhea as predominant symptom with macroscopically normal colonoscopy findings. After looking into detailed clinical history of patients including number of daily bowel motion, duration of diarrhea,  history for autoimmune disease (rheumatoid arthritis, diabetes mellitus), drug intake (Aspirin and Non-steriodal anti inflammatory drugs) and  laboratory evidence of chronic inflammation (erythrocytes sedimentation rate), biopsy taken from each segment of colon and from any abnormal looking areas. The diagnostic criteria for microscopic colitis are applied according the universally accepted histological criteria. Statistical analyses were performed by the use of Chi square test and at the level of significant alpha < 0.05 to compare our results in those with irritable bowel syndrome and those with chronic watery diarrhea with no definite cause.

Results: A total of 138 patients were included in the study. The frequency of microscopic colitis in all patients with chronic watery diarrhea was 10.8% (15/138), 13% (11/84) in those with no IBS, while in the diarrhea predominant subgroup of IBS patients was 7.4% (4/54), i.e.  26.6% (4/15) of patients with microscopic colitis full filled the Rome III criteria of irritable bowel syndrome. Diabetes mellitus present in 8.3% (7/84) and rheumatoid arthritis present in 3.5% (3/84) of patients with idiopathic chronic watery diarrhea. Aspirin intake history present in 7.1% (6/84), Non-steroidal anti-inflammatory drugs intake history present in 4.75 % (3/84) of patients with idiopathic chronic watery diarrhea.

Conclusion: Microscopic colitis frequency within the normal level similar to that is reported in worldwide in spite of high level of infectious causes of diarrhea in our society. MC can be identified in patients with chronic watery diarrhea and subset of diarrhea predominant IBS. It appears reasonable to test for microscopic colitis in those patients by performing a colonic biopsy and the clinical criteria for IBS are not sufficient enough to rule out the diagnosis of microscopic colitis.