Sigmoidoscopy and colonoscopy may help in the diagnosis of conditions such as melanosis coli due to laxative abuse, amebiasis, polyps, ulceration, Crohn’s disease, and ulcerative colitis. Upper GI endoscopy and biopsy help in the diagnosis of Crohn’s disease, giardiasis, intestinal lymphoma, lymphangiectasia, eosinophilic gastroenteritis, Whipple’s disease, mastocytosis, abetalipoproteinemia, fungal and protozoal infections.

Endoscopic examination and mucosal biopsies help in the diagnosis of some causes of acute diarrhea such as melanosis coli due to laxative abuse, inflammatory bowel disease ( Crohn’s disease and ulcerative colitis), Whipple’s disease and parasitic infections.

• Conditions such as melanosis coli due to laxative abuse, amebiasis, polyps, ulceration, Crohn’s disease, and ulcerative colitis may be diagnosed by endoscopic examination.
• Less common causes of acute diarrhea such as microscopic colitis, Whipple’s disease, and schistosomiasis may require biopsy for histological diagnosis.

• Crohn’s disease, giardiasis, intestinal lymphoma, lymphangiectasia, eosinophilic gastroenteritis, Whipple’s disease, mastocytosis, abetalipoproteinemia, fungal and protozoal infections may be diagnosed through upper GI endoscopy and biopsy.^[1]
• An aspirate of small intestinal contents may be sent for quantitative bacterial culture (aerobic and anaerobic) in case of suspected bacterial overgrowth and may be used for microscopy to detect parasites.