WASHINGTON (Reuters Health) -- When someone has all the signs of acute appendicitis, waiting to get a CT scan to confirm the diagnosis is not a good idea, researchers report. Compared with a straight-to-surgery approach, the CT strategy is linked to delayed surgery and increased risk of a burst appendix.

"There has been a somewhat reflexive use of CT since it has become widely available," Dr. Herbert Chen of the University of Wisconsin at Madison said during a presentation at Digestive Disease Week 2007, which is underway here.

Pre-operative CT is not necessary in cases with straightforward signs and symptoms of appendicitis, the investigator advised. "If, after a thorough physical examination, the diagnosis is still in question, then patients should be scanned." These patients tend to be older, female and have symptoms that are not typical for acute appendicitis.

Chen and his colleagues reviewed the records of 410 adult patients who underwent appendectomy at their institution over a 3-year period. Of these, 62 percent had a pre-operative CT scan, while 38 percent were taken straight to the operating room.

Patients who did not have a CT scan were in surgery within about 5 hours, but for those who had a scan, surgery was not performed for more than 8 hours.

The perforation rate was 17 percent in the patients who had a CT scan before surgery compared with 8 percent in those who did not.

The significantly longer time with the scan may also account for the more than two-fold increase in complications. Even with rapid intervention, there is a "significant complication rate" with acute appendicitis, Dr. Chen pointed out. "The CT should theoretically be relatively quick," Dr. Chen told Reuters Health. "But if contrast is used, then that takes time to swallow and be absorbed. Contrast is typically used, because physicians want to maximize the information obtained with exposure to radiation."