Study finds chance of appendicitis 'very low' if appendix is not visible on CT

The probability of acute appendicitis is very low if there is no distinctly apparent appendix on the CT scan, and in the absence of any secondary CT signs of appendicitis, says a study by researchers from the Northwestern University Feinberg School of Medicine and Northwestern Memorial Hospital in Chicago.

For the study, the researchers analyzed the CT scans of 366 patients with abdominal pain who were referred to rule out the diagnosis of appendicitis. In 46 of the patients, the appendix was not visible on the scan. After further tests or follow-up, the researchers found that only one of those 46 patients actually had acute appendicitis.

Usually, if a physician cannot see the patient's appendix on the CT scan, the physician might recommend further investigation or observation because he or she would not be able to rule out acute appendicitis, according to Paul Nikolaidis, MD, lead author of the study. "The findings of this study might provide information to change that course of action," said Dr. Nikolaidis.

"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."

The article appears in the October 2004 issue of the American Journal of Roentgenology.

A PDF of the full study is available upon request to reporters.

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