Patient education: Sigmoidoscopy (The Basics)

What is sigmoidoscopy? — This is a test that looks at the inner lining of the large intestine. The large intestine is also called the colon (figure 1).

A sigmoidoscopy is similar to a colonoscopy. But it only looks at the last part of the colon. A colonoscopy looks at the whole colon. A sigmoidoscopy does not require as much preparation.

Often, people have a sigmoidoscopy as a way to "screen" for colon cancer. It can also check for polyps in the colon or rectum. Polyps are growths that could turn into cancer. If you have polyps, the doctor can usually take them out during sigmoidoscopy. Taking polyps out lowers your chances of getting cancer.

Your doctor might also order a sigmoidoscopy if you have:

●Blood in your bowel movements

●A change in your bowel habits

●Rectal pain or persistent diarrhea that you cannot explain

How do I prepare for a sigmoidoscopy? — Your doctor will give you instructions about what to do.

Before your procedure, your doctor will do an exam. In some cases, they might also send you to get blood tests or other tests.

Your doctor will also ask you about your "health history." This involves asking you questions about any health problems you have or had in the past, past surgeries, and any medicines you take. Tell them about:

●Any medicines you are taking – This includes any prescription or "over-the-counter" medicines you use, plus any herbal supplements you take. It helps to write down and bring a list of any medicines you take, or bring a bag with all of your medicines with you.

●Any allergies you have

●Any bleeding problems you have – Certain medicines, including some herbs and supplements, can increase the risk of bleeding. Some health conditions also increase this risk.

You will also get information about:

●Eating and drinking before your procedure – You might be asked to follow a "low-residue" diet for a few days. This means avoiding foods that have a lot of fiber and are hard to digest. Then, you might need to switch to only clear liquids for 1 day before the procedure. Your doctor or nurse will tell you what foods you can and cannot eat.

●Cleaning out the colon – The last part of your colon needs to be cleaned out before a sigmoidoscopy. This is so your doctor can get a better look at the inside lining. You will get instructions for how to do a "bowel preparation." This often includes using laxatives and/or an enema shortly before the test. For an enema, you squirt liquid into your rectum.

●What help you will need when you go home – For example, you might need to have someone else bring you home or stay with you for some time while you recover. But this is not always the case.

Ask the doctor or nurse if you have questions or if there is anything you do not understand. Tell them if you are having any trouble preparing for your sigmoidoscopy.

What happens during a sigmoidoscopy? — When it is time for the procedure:

●You might get an "IV," which is a thin tube that goes into a vein. This can be used to give you fluids and medicines.

●Your doctor might give you medicines to help you relax. This is not always done for a sigmoidoscopy.

●You will lie on your left side with your knees bent.

●The doctor will put a thin, flexible tube, or "scope," into your anus (figure 2). The tube has a camera and light on the end. They will gently move the tube up into your rectum and colon.

●The doctor will use the camera to look inside the last part of your colon.

●The doctor might do a test called a biopsy. For a biopsy, they take a small piece of tissue from your colon. Then, they look at the tissue under a microscope to check for cancer or inflammation.

●The doctor might also remove any polyps (growths) that they see in your colon.

●You will not feel it if the doctor takes a biopsy or removes a growth.

●The procedure usually takes 5 to 15 minutes.

What happens after a sigmoidoscopy? — After a sigmoidoscopy:

●Most people can go back to their regular activities, if they did not get medicines to help them relax. This includes eating as usual.

●If you got medicines to help you relax, your doctor will recommend that you do not drive or go to work for the rest of the day.

●Your doctor will tell you when to start taking any medicines that you had to stop before the test.

●If your sigmoidoscopy shows any problems, you will probably need to get a colonoscopy. This is so your doctor can look at the rest of your colon. Your doctor will tell you if you need to schedule this.

What are the risks of a sigmoidoscopy? — Your doctor will talk to you about all of the possible risks, and answer your questions. Possible risks include:

●Bleeding

●Injury or tearing of the lining of the colon – If severe, this could require surgery.

●Infection

When should I call the doctor? — Call your doctor or nurse right away if you have any of the following after your sigmoidoscopy:

●Belly pain that is much worse than gas pain or cramps

●Bloated and hard belly

●Vomiting

●Fever

●A lot of bleeding from your anus

More on this topic

Patient education: Colonoscopy (The Basics)
Patient education: Colon and rectal cancer screening (The Basics)
Patient education: Colon polyps (The Basics)
Patient education: Clear liquid diet (The Basics)
Patient education: How to give an enema (The Basics)

Patient education: Flexible sigmoidoscopy (Beyond the Basics)
Patient education: Colonoscopy (Beyond the Basics)
Patient education: Screening for colorectal cancer (Beyond the Basics)
Patient education: Colon polyps (Beyond the Basics)