200 Diagnostic Yield of Colonoscopy in Young Adults With Lower Gastrointestinal Symptoms in Multicenter Midwest Cohort

INTRODUCTION: Serious gastrointestinal (GI) pathologies are common in older adults compared to young adults (≤40 years). There is a lack of data on the diagnostic yield of colonoscopy and flexible sigmoidoscopy in young adults with lower GI symptoms. We aimed to evaluate diagnostic yield of colonoscopy and compare overall diagnostic yield of colonoscopy versus flexible sigmoidoscopy in young adults with lower GI symptoms. METHODS: We reviewed diagnostic colonoscopies performed in young adults by 18 gastroenterologists at two different academic institutions between October 2016 to April 2019. Patients with family history of colorectal carcinoma were excluded. Diagnostic yield was calculated based on proportion of abnormal colonoscopy defined as having inflammatory bowel disease (IBD), microscopic colitis, advanced adenoma, or colorectal cancer (CRC). Presence of pathologies in left colon was considered for diagnostic yield of sigmoidoscopy. RESULTS: We included 454 patients with mean (SD) age was 31 (3) years, 162 (36%) were males and mean (SD) BMI was 30 (8.5). BRBPR was the indication for colonoscopy in 194 (43%) patients, 260 (57%) patients had colonoscopy for other lower GI symptoms (abdominal pain, diarrhea, constipation) but without BRBPR (Table 1). The overall diagnostic yield (DY) of colonoscopy in young adults with lower GI symptoms was 16%; IBD was seen in 43 (10%) patients, microscopic colitis 10 (2%), and advanced neoplasia/CRC 20 (4%) (Table 1). Overall DY in patients with BRBPR was significantly higher than patients without BRBPR (22% vs 11%, P = 0.001) (Table 2). The DY for IBD was also higher in young adults with BRBPR vs without BRBPR (15% vs 6%, P = 0.003) (Table 2). The overall DY was higher with colonoscopy compared to the predicted DY with flexible sigmoidoscopy (13.5% vs 9%) (Table 3). CONCLUSION: Significant proportions of young adults with BRBPR have abnormal pathology (22%) justifying endoscopic evaluation. For other lower GI symptoms, necessity of endoscopic evaluation should be determined clinically on a case-to-case basis as diagnostic yield is low. Colonoscopy rather than flexible sigmoidoscopy should be first line endoscopic evaluation in young patients with BRBPR due to the risk of missing IBD and advanced adenomas.