CT screening lowers negative appendectomy rate from 20% to 3% at urban hospital

Five years ago, the negative appendectomy rate at Massachusetts General Hospital (MGH) in Boston was 20%, but since the advent of CT screening, it has dropped to 3%, say MGH researchers. The negative appendectomy rate measures how often patients with symptoms of appendicitis have their appendix removed and then are diagnosed as not having acute appendicitis.

For the study, the researchers analyzed 663 patients who were examined on CT for suspected appendicitis. An appendectomy was performed on 268 of the CT-screened patients. Of these 268 patients, only 8 (3%) had a negative appendectomy.

"Prior to CT the negative appendectomy rate was 20% because there was no way to be sure whether appendicitis was present or not in most patients without surgery. Because CT is very accurate in imaging the appendix and because CT is very good at finding other conditions which mimic appendicitis, the negative appendectomy rate following CT has fallen dramatically. Fewer people are having to undergo appendectomy because CT can find the normal appendix and can frequently determine what is wrong prior to surgery," said James T. Rhea, MD, lead author of the study at MGH and who is now at San Francisco General Hospital in California.

According to the study, if a patient is suspected of having appendicitis, CT can help diagnose before surgery whether appendicitis is present or whether something else other than appendicitis is causing the patient's pain. "The patient's doctor should decide if CT is needed to increase the certainty that appendicitis is present or if something else is causing the problem, but in most patients CT will be helpful in deciding whether to remove the appendix. I know that if I had symptoms that might be appendicitis, I'd want to have a CT scan," said Dr. Rhea.