Normal Colonoscopy Findings
Precise knowledge of endoscopic anatomy is essential for training of colonoscopy, correct description of pathological findings, and understanding the clinical characteristics of colorectal disease. The division of the colon into segments is based primarily on anatomical rather than functional aspects: the rectum, sigmoid colon, descending colon, transverse colon, ascending colon, and cecum. The rectum, about 15–18 cm long, is the final straight part of the colon. The sigmoid colon forms, on average, 40 cm loop between the rectum and the descending colon. The descending colon runs relatively straight along the left flank, and the transverse colon is the longest and most mobile part of the colon. The ascending colon passes downward from the hepatic flexure to the cecum. The cecum is separated from the terminal ileum by the ileocecal valve. The normal variant of colonoscopy includes nonspecific erythema of rectum, iatrogenic mucosal injury, suction polyps, lymphoid nodules, everted appendix, aphthous ulcers, and uterine cervix. After operation, postoperative anatomical changes such as appendiceal stump after appendectomy and stoma may also be observed.