COVID-19 updates, including vaccine information, for our patients and visitors Learn More


Colorectal Cancer: Colonoscopy Q&A

Colon cancer is the third most common cancer in the United States and the second leading cause of cancer death, killing almost 50,000 Americans each year. The primary medical tool for detecting – and preventing – colon cancer is the colonoscopy, which involves prepping the patient’s bowel and inserting a scope to look for polyps and other potential warning signs.

Current guidelines call for men and women with average risk of colon cancer to undergo a colonoscopy (or one of two other tests) every 5 to 10 years after the age of 45. A recent survey by the Colon Cancer Alliance (CCA), however, pointedly notes that most people don’t follow the guidelines.

We asked Dr. William Sandborn, a gastroenterologist at UC San Diego Health, why people tend to avoid the procedure, what they should know and why the mandatory pre-procedure laxative tastes so terrible.

Q: The CCA survey found that 70 percent of adults age 50 and older who had been told they should get a colonoscopy had not done so, primarily due to fears about the procedure. What are patients typically afraid of, and what do you tell them to allay those fears?

A: I think patients are afraid of two things, pain from the procedure and embarrassment due to the personal nature of the procedure. From the pain perspective, patients receive intravenous sedatives which are adjusted during the procedure to ensure patient comfort. From the embarrassment perspective, patients wear a gown and are then covered with sheets during the procedure. This keeps the patient from feeling exposed.

Q: Most survey participants said they rely upon the Internet when seeking information about colonoscopy screenings. Is that a good resource? What specific kinds of information should people look for?

A: The Internet can sometimes be a good source of information, but it is variable in quality and accuracy, and the specific details might not apply to an individual patient. Most physicians who perform colonoscopies have information that is provided to the patient prior to the procedure and a staff of nurses and assistants who can answer questions. Getting your information directly from the physician and the endoscopy site that will perform your procedure is probably the best strategy.

Q: What’s the status on virtual colonoscopies, which use imaging technologies instead of an endoscope? Are they comparable to actual colonoscopies? Better? Worse?

A: Virtual colonoscopy is an x-ray test performed with a CAT scan machine. The accuracy is generally comparable to colonoscopy. However, patients still have to undergo a bowel prep, they are exposed to diagnostic radiation from the CAT scan, and if a polyp is detected (this can happen in up to 30 percent of cases), then they still have to undergo a colonoscopy to have the polyp removed, which means a having a second procedure. For all of these reasons, most colon cancer screening examinations are still performed using colonoscopy.

Q: The vast majority of people surveyed said bowel prep was the hardest part of the colonoscopy testing experience. That brings up a question asked by almost every person who’s ever gone through the process: Why can’t they make a better-tasting liquid purgative?

A: This is a great question, and whoever finds the answer is going to have a good business and a lot of grateful customers. One secret is that your taste buds are on the front two-thirds of your tongue, so if you use a flexible straw and put the end of the straw at the back of your tongue you can swallow the prep without tasting it.

UC San Diego Health Expertise

GI Quality Seal 

UC San Diego Health is at the forefront of endoscopic technology. Our physicians utilize endoscopy in combination with other diagnostic and surgical techniques to effectively address numerous conditions through the least invasive approaches possible. Our Endoscopic Ultrasound (EUS) and Interventional GI Endoscopy Program is recognized by the American Society for Gastrointestinal Endoscopy as a premier program in the United States. Program Director Thomas Savides, MD, is a past councilor for the American Society for Gastrointestinal Endoscopy.

Appointments & Referrals


La Jolla

Meet Our Specialists