Flexible sigmoidoscopy is performed as described below for colonoscopy, except that IV medication is usually not needed. Rigid sigmoidoscopy is usually performed with the patient in the knee-chest position. After rectal examination, the perianal area is examined, and the lubricated instrument is gently inserted 3 to 4 cm past the anal sphincter. The obturator is removed, and the instrument is inserted under direct vision. An anoscope is inserted its full length as described above for rigid sigmoidoscopy, usually with the patient in the left lateral position.
Complications are exceedingly rare when the procedure is properly performed.
Therapeutic indications include removal of polyps, coagulation of bleeding sites, reduction of volvulus or intussusception, and decompression of acute or subacute colonic dilatation. Absolute contraindications include acute shock, acute MI, peritonitis, intestinal perforation, and fulminant colitis. Relative contraindications include poor bowel preparation or massive intestinal hemorrhage, poor patient cooperation, diverticulitis, recent abdominal surgery, history of multiple pelvic operations, or a large hernia. Patients with cardiac or proximal joint prostheses need antibiotic prophylaxis to prevent endocarditis. After rectal examination in the left lateral position, a colonoscope is gently inserted through the anal sphincter into the rectum.