Flexible signoidoscopy is a procedure that is commonly used by primary
care physicians for the evaluation of rectal disorders and for colore
ctal screening. Retroflexion of the endoscope improves views of the an
orectum and rectal vault, which increases the diagnostic yield of sigm
oidoscopy. We report three cases of rectal lesions that were not detec
ted when flexible sigmoidoscopy was performed without retroflexion. Th
e lesions were all malignant or premalignant. The illustrative cases d
emonstrate the value of retroflexion in flexible sigmoidoscopy for the
detection of rectal lesions.