Flexible sigmoidoscopy, or flex sig, is a procedure used to see inside the sigmoid colon (the last one-third of the colon) and rectum (which connects the sigmoid colon to the anus). Here’s how it works: your doctor inserts a flexible tube (about the thickness of a finger) into the anus and slowly advances it into the rectum and lower part of the colon. Probably doesn’t sound too pleasant, but through this procedure, your doctor can detect inflamed tissue, abnormal growths and ulcers. This screening method is used to look for early signs of cancer and can help doctors diagnose unexplained changes in bowel habits, abdominal pain, bleeding from the anus and weight loss.
Preparation for flex sig can vary. Some doctors will recommend one or more enemas before the procedure, others will recommend a clear liquid diet for one to three days, while others will advise you to forgo any prep. Your doctor will tell you the specifics on what will be the best prep method for you.
So here’s what everyone wants to know: what’s actually going to happen to me during a flex sig? To start the procedure, you will lie on your left side on an exam table. Your doctor then inserts a long, flexible, lighted tube called a sigmoidoscope, or scope, into the anus and slowly guides it through the rectum and into the sigmoid colon. The scope inflates the colon with air to give the doctor a better view. A tiny camera mounted on the scope transmits a video image from inside the colon to a computer screen, allowing the doctor to carefully examine the tissues lining the sigmoid colon and rectum.
You may be asked to move periodically so the scope can be adjusted for better viewing. The lining of your colon is then examined again as the scope makes its way out. You may experience a feeling of pressure, bloating or cramping during the procedure, but this will quickly subside once the air passes out of you. And the best part: as soon as the procedure is finished, you can get dressed, leave on your own, drive and resume your normal diet and activities right after.
If your doctor sees an area that needs further evaluation, he or she may take a biopsy to be analyzed. Biopsies are used to identify many conditions, and your doctor may order one even if cancer isn’t suspected.
If small polyps are found, they may be removed using special tools passed through the scope. Larger polyps, too big to remove during the procedure, can be biopsied and tested for colon cancer. If a biopsy taken during a flex sig comes back positive for colon cancer, you will need a colonoscopy to remove that polyp.
Flex sig and biopsies are safe when performed by doctors specially trained and experienced in these procedures. Complications are rare, but it's important you recognize early signs in case they do arise. Contact your doctor if you experience severe abdominal pain, fevers and chills, dizziness or rectal bleeding. Note that rectal bleeding can occur several days after the exam.
For more information about flexible sigmoidoscopy, please call the Colon Cancer Alliance’s Toll-free Helpline at (877) 422-2030.