When you go in for a medical procedure, there are all kinds of questions that typically run through your mind: will it hurt, how long will it take, and who will be doing the procedure? But one question that probably never occurs to most people is whether the doctor's equipment is clean. We just assume it is. Now, some say that assumption might be wrong, that certain instruments called scopes are being re-used time after time without proper cleaning. Here's Cindy Dibiasi with more on this frightening possibility.

CINDY DIBIASI: Anita McKenzie enjoys moving to a beat. Several nights a week you can find her at a gym exercising her passion.

ANITA McKENZIE: I love dancing. It's like that's the way that I get my exercise, that's the way that I keep my weight where I like to have it.

CINDY DIBIASI: A self-described “health nut,” Anita always watched what she ate and never smoked. And after several members of her family died from colon cancer, she decided to get tested with a colonoscopy.

ANITA McKENZIE: Given my family history, it hit home with me and I said, well, I'd better check this out and do something about it, just to make sure that I'm ok.

CINDY DIBIASI: In a colonoscopy doctors use a flexible endoscope, a long tube, with a tiny camera on the end that allows them to see and remove suspicious growths.

The test showed Anita had two such growths and they were successfully taken out. But that wasn't the end of the story. A couple of months after the test, Anita came down with something.

ANITA McKENZIE: I was feeling like I had the flu, very sluggish, tired and weak.

CINDY DIBIASI: It turns out Anita had hepatitis, an infectious disease which she claims she picked up from her colonoscopy. Anita says the test she took to stay healthy in fact made her sick.

ANITA McKENZIE: It was traumatic, I felt ashamed because I just felt dirty.

DAVID LEWIS, PhD, UNIVERSITY OF GEORGIA: There is a significant risk of infection with endoscopes and few people are aware.

CINDY DIBIASI: David Lewis is a microbiologist. He charges that improper cleaning of endoscopes, used not only to diagnose colon cancer but a host of other conditions, may be spreading infection from patient to patient.

DAVID LEWIS, PhD: I estimate that 2.7 percent of the procedures result in some sort of infection. That amounts in the United States to about 270,000 infections a year. That's everything from the common cold to hepatitis.

CINDY DIBIASI: But Lewis says most of those infections are never reported, because of fear of lawsuits, or no one bothers to trace the cause.

DAVID LEWIS, PhD: When a patient becomes infected, they go to a different doctor than the doctor that did the endoscopy, so the two events are often not connected.

CINDY DIBIASI: The Food and Drug Administration regulates the equipment used in the cleaning process and helps write the cleaning guidelines.

In the early 1990's the FDA examined the interiors of more than 200 endoscopes which were supposedly clean. It found one out of five was dirty. What's more, nearly half of the facilities it inspected had at least one endoscope, which was ready to be used on a patient, which was in the FDA's words, “visibly encrusted with debris.” FDA official Timothy Ulatowski says the problem has improved but he admits there are still some risks.

TIMOTHY ULATOWSKI, FOOD AND DRUG ADMINISTRATION: Most of the problems that we've encountered have been attributed to user problems, user errors, breakdowns in procedure by the users.

CINDY DIBIASI: The cleaning process is difficult and tedious. First, a technician must carefully scrub the intricate inside channels of the endoscope with tiny brushes. If debris is missed, it can harden and chip off during other procedures. Next the scope is put into a high tech dishwasher that cleans it either with a disinfectant or with sterilizing chemicals. After being rinsed with purified water, it's flushed with alcohol to dry. But too often hospitals take short cuts according to Lewis.

DAVID LEWIS, PhD: We need to do two things, a better job of cleaning, and follow manufacturers and FDA recommendations with sterilization and disinfection.

CINDY DIBIASI: Lewis has gotten the attention of congressman Anthony Weiner who's calling on the government to investigate.

REP. ANTHONY WEINER, (D) NEW YORK: We don't know how big a problem this is. And I've always pursued the philosophy that if we have the ability to make it a little bit safer, an ability to make it a little bit surer for consumers of medical care, we should try to do that.

CINDY DIBIASI: Gastroenterologist Stanley Benjamin does as many as eight colonoscopies a day at Georgetown University Medical Center. He tells his patients the procedure is safe.

STAN BENJAMIN, MD, AMER. SOCIETY FOR GASTROINTESTINAL ENDOSCOPY: I've had my family members endoscoped in this unit. I would not do that if I thought I was exposing them to some great risk.

CINDY DIBIASI: Dr. Benjamin says the medical profession goes to great lengths to make sure endoscopes are clean. And he says any possible risks are far outweighed by the benefits.

STAN BENJAMIN, MD: Five percent of the U.S. population will get colon cancer. The risk of getting an infection related to an endoscopy is one in 1.8 million procedures. Get a colonoscopy.

CINDY DIBIASI: Anita is better now and says she's not sorry she got a colonoscopy but next time she'll make sure the doctors are more careful.

ANITA McKENZIE: I want to continue to maintain my health and be cautious, but it's just making me feel very vulnerable.

SHARYL ATTKISSON: You should not let fear of infection keep you from getting any exam that involves an endoscope. But if you're concerned, here are some questions to ask your doctor beforehand. Do you have written procedures for endoscope cleaning? Have you or your staff been specially trained in scope cleaning? How is the cleaning process monitored? The answers are no guarantee that the scope is clean. But if your doctor evades the questions, there may be a problem and you should get the exam done at another place.