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Getting ready for a flexible sigmoidoscopy: why, the prep, the day of, and after
For anyone who has a flexible sigmoidoscopy coming up, or who is helping someone through one. The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK, part of the NIH) says flexible sigmoidoscopy is a procedure in which a doctor uses a flexible tube with a camera to look inside your rectum and lower colon, to find the cause of symptoms such as bleeding from the anus, changes in bowel movements, belly pain or weight loss, and, rarely, to screen for colorectal cancer. This page passes on, by name, what NIDDK says: why doctors use it; your health, your medicines and the special diet; the bowel prep; what happens during the procedure; and the results, the risks, and when to get care right away. It builds the words to say and the questions to ask, and prints a card for the fridge.
Right now
- Trouble breathing, chest pain, fainting, or heavy bleeding with dizziness? Call 911 (ours).
- After a flexible sigmoidoscopy: severe pain or bloating in your belly, fever or vomiting, bloody bowel movements that do not get better, bleeding from the anus that does not stop, dizziness, or weakness? NIDDK says to seek care right away.
- Side effects keep you from finishing the bowel prep? NIDDK says to call a health care professional.
- Not sure whether to stop a medicine before it? Ask the doctor who ordered the procedure. Do not stop or change a prescribed medicine on your own (ours).
- It is all too much, or you are thinking of ending your life? Call or text 988, any hour (ours).
More help
- The belly, on this site: Getting ready for a colonoscopy · Colon polyps · Hemorrhoids · Bleeding in the digestive tract · Ulcerative colitis · Crohn’s disease · Getting ready for an upper GI endoscopy · An upset stomach: find the right page.
- Getting there and getting ready: Rides to care · My medicines list · Symptom diary · Get ready for your appointment.
- If the news is hard: When the doctor says cancer.
- Care and costs: When you need a doctor and can’t pay · Medical bills.
- In a crisis: Help right now (988, 911). All our free tools.
An upset stomach, and not sure this is the right page? The pages on this site for throwing up, diarrhea, heartburn and constipation, on one list.
This page and its wording were written with AI (Claude) for Scarlet Beast (our AI policy). No doctor or nurse has reviewed it. The facts were read on October 17, 2026 on NIDDK’s Flexible Sigmoidoscopy page (NIH) and its Spanish version, both last reviewed in July 2024 and saying the same things, except the rate of perforation, which differs between the two, so we give no number for it; the cards also point to NIDDK’s Colonoscopy, Virtual Colonoscopy and Colon Polyps pages. The numbers (screening usually from age 45; older than 75, talk with your doctor; about 10 to 20 minutes; bleeding in about 1 in 20,000 procedures) are NIDDK’s. Ours: 911 for trouble breathing, chest pain, fainting, or heavy bleeding with dizziness; asking ahead which medicines change, and never stopping one on your own; writing down when the special diet and the clear liquids start; asking which prep and when; asking whether you will get a sedative and need a ride; telling the team you are nervous; asking who tells you the results and whether a colonoscopy comes next; the card; 988 when it is too much; health centers when money is tight; and the order of the steps. What we left out: laxative, enema and sedative names, brands, doses, and clinical pages for providers. This page saves nothing and loads no trackers.