Sigmoidoscopy

A sigmoidoscopy is a medical procedure that examines the lower part of the large intestine and rectum. It’s an important tool for detecting problems and keeping people healthy. 

Whether you are scheduled for a sigmoidoscopy or want to learn more, Banner Health is here to share more about this important procedure.

What is a sigmoidoscopy?

A sigmoidoscopy, or flexible sigmoidoscopy, is a medical procedure used to examine the lining of the sigmoid colon to look for problems or signs of disease. The sigmoid colon is the lower part of the large intestine (colon) near the rectum. 

Sigmoidoscopies are just one of many endoscopy procedures that look inside the body. Gastroenterologists perform sigmoidoscopies during office visits, in hospitals or outpatient facilities. 

The gastroenterologist passes a thin, flexible tube fitted with a light and tiny camera, called an endoscope, into the anus and rectum to examine the lower third of the colon. Sometimes, small instruments can be passed through the tube to take a small piece of tissue (biopsy) or abnormal growths (polyps) to confirm a diagnosis. Tools can also be used to repair or treat conditions.

What is the difference between a sigmoidoscopy and a colonoscopy?

While a sigmoidoscopy only examines the last one-third of the large intestine (about 20 inches of the colon), a colonoscopy looks at the entire colon. Unlike a colonoscopy, sigmoidoscopy does not require sedation (medication to help you relax and feel sleepy). It also does not require the full bowel prep needed for a colonoscopy.

What is the difference between a flexible sigmoidoscopy and a rigid sigmoidoscopy?

A rigid sigmoidoscopy, also called a proctoscopy, uses a stiffer or harder scope rather than an endoscope. The shorter, unbending tube (about 25 cm long) is used to examine the rectal lining and does not extend as far into the colon as a sigmoidoscopy. A proctoscope is often used to diagnose and treat conditions such as hemorrhoids (swollen veins in your rectum and anus), rectal bleeding or swelling (inflammation) in the rectum.

Why might I need a sigmoidoscopy?

Gastroenterologists use flexible sigmoidoscopies for several reasons. Here is why your provider may recommend one:

• Preventive screening: A sigmoidoscopy is one type of test used to screen for colorectal cancer (colon cancer and rectal cancer), but it is not widely used in the U.S. for this purpose. This is because a sigmoidoscopy looks only at the lower portion of the colon, not the entire colon. If your provider believes your symptoms are due to a problem in the lower colon alone, they may decide a sigmoidoscopy is a better test. However, if your provider detects cancer during a sigmoidoscopy, they will want to search the rest of your colon for cancer with a colonoscopy.
• Diagnostic: If you are experiencing symptoms like rectal bleeding, changes in your bowel (pooping) habits or unexplained weight loss, a sigmoidoscopy can help your provider find the underlying cause. It allows for a visual examination of the colon to diagnose conditions like polyps (both benign and cancerous), hemorrhoids, inflammatory bowel disease, colitis and Crohn’s disease.
• Treat a condition: It can be used to treat a problem. By attaching tiny tools to the endoscope, your provider can remove polyps or hemorrhoids. 

Possible complications of a sigmoidoscopy

Sigmoidoscopies are very safe procedures. But like other endoscopies, they carry potential risks. These risks, though rare, include:

• Bleeding after a biopsy or polyp is removed
• A small tear or hole (perforation) in the wall of the colon or rectum
• Infection if the equipment is not properly cleaned and sterilized

If you have any worries or questions about getting a sigmoidoscopy, it's important to talk to your provider. They’ll help you understand everything and ensure your safety during the procedure.

How to prepare for a sigmoidoscopy

Your health care provider will give you specific instructions on how to prepare for a sigmoidoscopy, but generally you’ll need to:

• Sign a consent form: You may be asked to sign a form giving your provider permission to perform the procedure. Read the form carefully and ask your provider if anything needs clarification.
• Possible bowel prep: Before a sigmoidoscopy exam, you may be asked to empty your colon. This means you may eat a restricted diet the day before the test and take something to make you poop before the test. It may differ from the type of bowel prep you would do for a colonoscopy. 
• Adjust medications: Your provider may ask you to temporarily stop certain medications or adjust your dosage, especially blood thinners, to reduce the risk of bleeding during the procedure. If you have ongoing conditions such as diabetes or heart disease, your provider will give you specific instructions about your medications.

Let your provider know if you have allergies or reactions to medications, latex or tape and if you are pregnant or think you may be pregnant.

Most people do not need sedation or anesthesia, but you can discuss it with your provider if you are nervous about the procedure. Sigmoidoscopies are not painful. You may feel pressure and some gas pain, but this will pass after the test.

What to expect during a sigmoidoscopy

How a sigmoidoscopy is performed may vary depending on your condition and your provider’s practices. In general, it follows this process:

• You will change into a gown and remove any jewelry or accessories. This ensures that you are comfortable during the procedure and allows your provider easy access to the area being looked at.
• You will lie on your side on an exam table with your knees bent toward your chest (fetal position) or another specific position. This position helps the provider have a clear view of the anus and rectum.
• Your provider will gently insert the scope into your rectum and advance it into your colon. The light and camera at the end allow them to see inside your colon and rectum on a monitor.
• The camera attached to the endoscope will send pictures to a screen so your provider can see inside your digestive system. Tools may also be used to take a sample, remove polyps or make a small repair.
• You may experience bloating, pressure or cramping, but it should not be painful. Your provider may offer suggestions to help minimize discomfort, such as taking slow, deep breaths.
• When the exam is done, the scope will be taken out.

The procedure may take 5 to 10 minutes. It could take longer if your provider needs to take a tissue sample, remove polyps or make a small repair.

Recovery from a sigmoidoscopy

Once the sigmoidoscopy is complete, you will be given time to rest and recover. Your provider will discuss their findings with you and any further steps that may be necessary based on the results.

You may experience bloating, gas or mild stomach cramping. These should get better quickly. You may see a small amount of blood in your stool (poop), but this should stop within a day or so.

After the procedure, you should be able to eat, drink and resume normal activities unless instructed otherwise. 

Call your provider immediately if you have any of the following:

• Fever and chills
• Belly pain that doesn’t go away
• Dark or black stools
• Feel dizzy or faint
• Have not had a bowel movement for 3 days after your procedure

Call 911 or have someone take you to the nearest emergency department if you experience any of the following:

• Sudden chest pain
• Difficulty breathing and swallowing or gasping for air 
• Sudden loss of consciousness

How do I understand my results?

After your sigmoidoscopy, your health care provider will review what they found during the exam. If they took a tissue sample, the results may take some time to get.

If everything looks normal, it means your sigmoid colon is healthy. If there are signs of inflammation, polyps or ulcers, your provider may suggest additional testing and treatments. If you have any questions, ask your provider to help you understand.

Expert care 

Has your health care provider suggested a sigmoidoscopy? If so, Banner Health’s experts are here to help. Our dedicated team uses cutting-edge technology to ensure the best possible care.