FRIDAY, Oct. 1 (HealthDayNews) -- The probability of acute appendicitis is very low if the appendix is not clearly visible on a computed tomography (CT) scan and if the patient has no secondary CT signs of appendicitis, says a study in the October issue of the American Journal of Roentgenology.

Researchers at Northwestern University and Northwestern Memorial Hospital in Chicago analyzed the CT scans of 366 people with abdominal pain. In 46 of the patients, the appendix was not visible on the CT scan. Further tests and follow-up revealed that only one of those 46 patients actually had acute appendicitis.

Typically, if a doctor can't see the patient's appendix on the CT scan, the doctor would recommend further investigation or observation to rule out appendicitis.

"The findings of this study might provide information to change that course of action," lead author Dr. Paul Nikolaidis said in a prepared statement.

"Physicians treating patients with abdominal pain in these instances can be more confident that the chance of their patient having acute appendicitis is actually very low. This is good news for the patient, as well, since it may shorten their hospital or emergency room or observation unit stays, and the real cause of their pain can be more quickly ascertained," Nikolaidis said.

More information

The U.S. National Digestive Diseases Information Clearinghouse has more about appendicitis.