Digestive Disease Week 2009: Patients with Inflammatory Bowel Disease at Risk for Extremely High Levels of Radiation Exposure

CHICAGO, June 2, 2009 — Patients with inflammatory bowel disease (IBD), particularly those with Crohn's disease (CD), are at potential risk for dangerously high levels of radiation exposure.

In reporting their findings at Digestive Disease Week 2009, Canadian researchers primarily attributed the excess exposure to computed tomography (CT) scans, sometimes performed excessively, they said, during diagnosis and for monitoring disease status.

Karen Kroeker, MD, a Fellow in the Division of Gastroenterology at the University of Alberta in Edmonton, et al counted the total number of abdominal radiographic studies for 392 patients with CD and 195 patients with ulcerative colitis (UC) between September 2003 and September 2008. They calculated the amount of ionizing the patients received in millisieverts (mSv).

The average radiation exposure was 2.77 mSv per patient per year for patients with CD patients and 1.77 mSv per patient per year for patients with UC.

Radiation exposure was 159% above background levels for patients with CD and 39% above background levels for patients with UC.

"Three quarters of the radiation exposure from abdominal imaging for both CD and UC patients was from CT scans," Dr Kroeker told Medscape Gastroenterology in an interview prior to her presentation. "One third of CD patients had abdominal or pelvic CT scans, compared with one fifth of UC patients."

The average age of patients with CD was 40 years (range, 15–84 years) and of patients with UC was 39 years (range, 17–77 years). The average age of patients who had undergone CT scans was 42 years for patients with CD and 36 years for patients with UC.

Dr Kroeker's team found that 34% of the CT scans for patients with CD and 41% for patients with UC were performed in the emergency department. In addition, 67% of patients with CD were subsequently admitted, compared with only 38% of patients with UC.

The most common reasons for CT scans in patients with CD were to exclude abdominal abscess (26%), for unexplained abdominal pain (14%), and to exclude bowel obstruction (12%). For patients with UC, the most common reasons were to exclude renal colic (24%) and for unexplained abdominal pain (18%).

"Clinicians need to be more judicious in their use of CT scans in IBD patients," Dr Kroeker advised. "It isn't reasonable to think we can eliminate them entirely, but we need to consider if we can get the information we need through other procedures, blood tests . . . even conventional X rays have lower levels of radiation . . . and we shouldn't overlook the value of a careful history and physical examination."

"Distinguishing between UC and CD could prevent the unnecessary use of CT scan," Dr Kroeker continued. "We need them to assess abscesses, stricturing disease, and possible bowel obstruction, and it may help in determining if surgery is needed or not, but it isn't needed for all cases of abdominal pain. Check the patient's record. A CT scan may have been done recently, and we have to consider if doing another one will really add useful information."

"The pros and cons [of CT scanning] have to be weighed carefully," Sunanda V. Kane, MD, Professor of Medicine in the Department of Gastroenterology and Hepatology at the Mayo Clinic in Rochester, Minnesota, told Medscape Gastroenterology. "[Magnetic resonance imaging] may be a better test. We have to think about what a CT scan can do and what kind of information it gives us versus what other tests can give us."

Dr Kane was the moderator of a panel on IBD, during which Dr Kroeker presented her findings.

"These findings are especially important given the age of the patients. Some of them are very young, when radiation can have especially pronounced adverse effects," Dr Kane pointed out.

Source: Medscape Medical News