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UT Southwestern Medical Center’s highly skilled gastroenterology team has many years of colonoscopy experience and advanced training in removing complex colon polyps.

With a modern outpatient clinic and endoscopy area, we’re capable of providing immediate and expert care for any patient who needs screening for or is concerned about colorectal cancer.  

A colonoscopy is an exam that detects colorectal cancer or finds colon polyps before they become cancerous. It can also help to diagnose other diseases of the gastrointestinal tract, such as inflammatory bowel disease, including Crohn’s disease and ulcerative colitis.

The procedure involves the insertion of a scope with a tiny camera throughout the entire colon. Colonoscopy is the most popular colon cancer screening technique, administered to millions each year. One of the most significant advantages of a colonoscopy is that the physician can remove precancerous polyps found during the procedure, preventing these polyps from ever developing into cancer. 

Although colonoscopy is the gold standard for colon cancer screening and prevention, there are a variety of screening tests including virtual colonoscopy, which might be an option for some patients.

UT Southwestern’s physicians use colonoscopy to diagnose and treat conditions such as:

What to Expect

Our team will discuss, in detail, with each patient how to prepare for a colonoscopy. In the days before the procedure, patients will be asked to limit and eliminate certain foods from their diet. They must also cleanse the bowel with an oral laxative so that the test can visualize as much of the colon surface as possible to detect any abnormalities.    

During the exam, patients are sedated and should not feel any discomfort. The doctor inserts a long flexible tube through the rectum and moves it through the entire large intestine. As the tube moves through the intestine, the doctor is able to see the lining of the colon, providing the doctor information about the health of the colon and the presence of any precancerous lesions. If a precancerous polyp is identified, it can be removed immediately during the examination. The procedure itself takes anywhere from 30 to 60 minutes.

After the test, patients stay in a recovery room for about 30 minutes to allow the sedation to wear off. Patients will need to arrange for someone to drive them home.

Virtual Colonoscopy

In certain cases, patients may elect to have what’s called a virtual colonoscopy. In this procedure, our radiologist experts use a computed tomography (CT) scanner to take 3D images of the intestine. The day before the CT scan, patients also drink a bowel-cleansing liquid with a contrast fluid, which allows the radiologists to see the lining of the colon more clearly.

On the day of the exam, the patient undresses and lies stomach-side down on the CT table. A thin tube is inserted into the patient’s rectum to fill the colon with air. The technologist goes inside a control room to monitor the one- to two-minute CT scan; the patient can speak to the technologist at any time using a microphone built into the scanner. The CT tech then returns to assist the patient in turning over on the table, and the one- to two-minute CT scan is repeated. The radiologist reviews the pictures for completeness, and the tube is removed. The patient is assisted off the table and can get dressed and return immediately to normal activities. The air in the colon is slowly absorbed with no associated discomfort.  

The average exam takes approximately 20 minutes, from start to finish.

Patients must still prepare similarly to the standard colonoscopy – by limiting high-fiber foods and emptying the colon the day before the test. This study has the advantage of not requiring anesthesia but does not allow for the immediate removal of polyps identified at the time of the exam. If a polyp of 1 cm or greater is found, then a colonoscopy is recommended for removal. Smaller polyps might require a shorter-term follow-up surveillance exam in three years, depending on the doctor’s recommendation.

Learn more about what to expect during CT scans at UT Southwestern .

When to Have a Routine Colonoscopy

For men and women who are at average risk for developing colorectal cancer, we recommend beginning colon cancer screening at age 45. The frequency of repeat colonoscopies will be determined based on the findings of each patient’s results from the procedure. For example, an individual with a large number of precancerous polyps will be asked to return for a repeat colonoscopy sooner than an individual with no polyps.

Patients who are at an increased risk of colorectal cancer should begin colorectal cancer screening before age 45 or be screened more often.

Common increased risk factors include:

  • Family history of inherited colorectal cancer syndromes such as Lynch syndrome or familial adenomatous polyposis (FAP)
  • Family history of colorectal cancer or polyps
  • Personal history of colorectal cancer or polyps
  • Personal history of chronic inflammatory bowel disease