Colonoscopy and sigmoidoscopy are screening exams for colorectal cancer (commonly referred to as "colon cancer"). But false information and a misplaced sense of modesty have scared some people away from these lifesaving tests. Here are some questions you might have and some answers for them:

• What is a colonoscopy?
• What is a sigmoidoscopy
• Will it hurt?
• Who will do the exam?
• Will I be in a private room?
• How do I prepare? Will I need to miss work?
• How will I feel afterward? Will I need someone to drive me home?
• What if they find something?
• Why are these tests so important?

What is a colonoscopy?

A colonoscopy is an exam that allows a doctor to closely look at the inside of the entire colon. The doctor is looking for polyps or signs of cancer. Polyps are small growths that over time can become cancer. The doctor uses a thin (about the thickness of a finger), flexible, hollow, lighted tube that has a tiny video camera. This tube is called a colonoscope. The colonoscope is gently eased inside the colon and sends pictures to a TV screen. Small amounts of air are puffed into the colon to keep it open and allow the doctor to see clearly.

The exam itself takes about 30 minutes. Patients are usually given medicine to help them relax and sleep during the procedure.

Your doctor decides how often you need this test, usually once every 10 years, depending on your personal risk for colon cancer. It's important for people to talk with their doctor to understand their risk for colon cancer, the guidelines they should follow for testing, and whether they need to start being tested at age 50 or earlier.

What is a sigmoidoscopy?

During a sigmoidoscopy, a doctor closely looks at the lower parts of the colon, called the sigmoid colon and the descending colon, for signs of cancer or polyps. Polyps are small growths which can over time become cancer. The doctor uses a thin (about the thickness of a finger), flexible, hollow, lighted tube that has a tiny video camera. This tube is called a sigmoidoscope. The sigmoidoscope is gently eased inside the colon and sends pictures to a TV screen. Small amounts of air are puffed into the colon to keep it open and allow the doctor to see clearly.

The exam takes 10 to 20 minutes. The patient usually doesn't need medicine, but this may be an option you can discuss with your doctor.

Your doctor decides how often you need this test, usually once every 5 years, depending on your personal risk for colon cancer. It's important for people to talk with their doctors to understand their risk for colon cancer. They will want to be sure about the guidelines they should follow for testing, and whether they need to start being tested at age 50 or earlier.

Will it hurt?

No, these two exams are not painful. For the most part, patients are given medicine to sleep through the colonoscopy, so they won't feel anything. Sigmoidoscopy doesn't require medicine to make the patient sleepy, so some patients find the air pressure uncomfortable. Air is pumped into the cleaned-out colon to keep it open so that doctors can get the best pictures. While it may cause slight discomfort, it should not hurt.

Who will do the exam?

A colonoscopy is almost always done by a doctor, usually a gastroenterologist (a doctor whose specialty is the digestive tract) or a surgeon.

Sigmoidoscopy exams are often done by primary care doctors (general practitioners, family doctors, and internal medicine doctors) in their offices. Studies show that a well-trained clinical nurse specialist, nurse practitioner, or physician’s assistant can do sigmoidoscopies very well too.

Will I be in a private room?

Colonoscopy is done in a private area; it may be a hospital outpatient department, a clinic, an ambulatory surgery center, or a doctor's office. The patient's privacy is a top concern.

Sigmoidoscopy is always done in a private room, too; no other patients are around. Doctors and nurse specialists are professional and very careful to respect the patient's privacy.

How do I prepare? Will I need to miss work?

The preparation for both colonoscopy and sigmoidoscopy makes you to go the bathroom a lot! The doctor will give you instructions. Read these carefully a few days ahead of time, since you may need to shop for special supplies and get laxatives from a pharmacy. If you are not sure about any of the instructions, call the doctor's office and go over them step by step with the nurse. Many people consider the bowel preparation (often called the "bowel prep") the most unpleasant part of the test. You follow a special diet the day before the exam and take very strong laxatives before the procedure. You may also need enemas to clean out the colon. The key to getting good pictures is to have the colon cleaned out.

Because colonoscopy is usually done with drugs that make you sleepy, people usually will miss a day of work. Ask your doctor whether you'll need to miss work before a sigmoidoscopy. For either test you'll need to stay close to a bathroom. You might want to schedule the exam for a Monday, so you can be at home the day before without taking that day off work.

How will I feel afterward? Will I need someone to drive me home?

Most people feel OK after a colonoscopy. They may feel a bit woozy from the drugs (anesthesia). They'll be watched and given fluids as they wake up. They may have some gas, which could cause mild discomfort. Because of the medicines given for the test, most facilities require that you bring someone to take you home.

After a sigmoidoscopy, you get up and walk out. There should be no problem driving yourself home, as long as you have not had any drugs to make you sleepy during the test.

What if they find something?

If a small polyp is found, your doctor will probably remove it. Over time some polyps could become cancer. If your doctor sees a large polyp, a tumor, or anything else abnormal, a biopsy will be done. For the biopsy, a small piece of tissue is taken out through the colonoscope or sigmoidoscope. It is sent to a lab to be checked under a microscope for cancer or pre-cancer cells.

Why are these tests so important?

Colorectal cancer screening helps people stay well and save lives. Regular colorectal cancer testing is one of the most powerful weapons for preventing colorectal cancer. Removing polyps prevents colorectal cancer from ever starting. And cancers found in an early stage are more easily treated. Nine out of 10 people whose colon cancer is discovered early will be alive 5 years later. And many will live a normal life span.

But too often people don't get these tests. Then the cancer can grow and spread without being noticed, like a silent invader. In many cases, by the time people have any symptoms the cancer is very advanced and very hard to treat.

Last Medical Review: 08/21/2009
Last Revised: 08/21/2009