A colonoscopy is a medical procedure designed to prevent and detect colorectal cancer. A colonoscopy examines the entire colon and rectum for polyps and any abnormalities. Polyps and abnormalities may be benign or cancerous. The invasive nature of the colonoscopy makes it a difficult choice for some individuals. According to the American Cancer Society, alternative procedures that can detect colorectal polyps and cancer include a barium enema, a sigmoidoscopy and a virtual colonoscopy.
Barium Enema
A barium enema uses X-rays to examine the lining of your rectum and colon, according to Medline Plus, a publication of the National Institutes of Health. Barium sulfate enters the colon via a lubricated enema tube placed in the rectum. A small balloon at the tip of the enema tube inflates to keep barium in the colon. Barium sulfate enables the images of the colon and rectum to appear distinctly on the X-ray. The procedure lasts 30 to 45 minutes. If X-rays show polyps or any abnormalities, a colonoscopy for polyp removal and biopsy will need to be performed.
Sigmoidoscopy
A sigmoidoscopy examines the lower large bowel of the colon and the rectum. A digital rectal exam occurs before the sigmoidoscope enters the rectum. A sigmoidoscope is a hollow tube instrument that can be rigid or flexible. The doctor uses the hollow center of the tube to see into the rectum and colon. The hollow shape of the tube also permits the entry of forceps and other instruments for polyp removal and biopsies. The procedure lasts 10 to 20 minutes, according to Medline Plus.
Virtual Colonoscopy
A virtual colonoscopy uses either MRI or CT scans to create three-dimensional images of the colon and rectum. Air pumps through a small tube inserted into the rectum to allow for a better view of the colon. Either the MRI or CT machine produces images of the colon and rectum while the patient lies inside. The specialized computer software used for this procedure combines images into three-dimensional pictures of the colon and rectum. The procedure lasts 20 minutes, according to Medline Plus. If images from the virtual colonoscopy show polyps or abnormalities, a colonoscopy for polyp removal and biopsy will need to be conducted.
