Pathological Patterns in Chronic Diarrhea With Normal Colonoscopy

Inclusion Criteria: * all patients with chronic diarrhea and had normal colonoscopy Exclusion Criteria: * Inflammatory bowel diseases (ulcerative colitis, crohns disease and indeterminate colitis). * Systemic disease associated with chronic diarrhea, e.g. Diabetes mellitus and Thyroid disease. * Drugs causing chronic diarrhea, e.g. antibiotics, antidepressants and angiotensin converting enzyme inhibitors. * Chronic diarrhea due to decreased digestion as in pancreatic insufficiency,bile acid deficiency and Infectious colitis