ACEP: CT No Help in Suspected Appendicitis

NEW ORLEANS Oct. 16 -- CT scans for patients with suspected acute appendicitis add no diagnostic value and may be associated with worse outcomes, reported researchers here.

Those who had CT scans before surgery were about three times more likely to have a perforated or gangrenous appendix by the time they got to the operating room, a New York team said at the American College of Emergency Physicians meeting here.

In a retrospective study of all patients with suspected appendicitis who presented to an urban ER over one year and who later went on to appendectomy, those whose care was delayed by a wait for a CT scan had a worse outcome than patients who were sent to the first available OR, found Christopher Perry, M.D.. of Lincoln Medical and Mental Health Center, and colleagues, and Weill Cornell Medical School.

In addition to increasing the risk of a worse outcome, "a CT scan also exposes patients to increased radiation as well as potential radiocontrast adverse events," the investigators wrote in a poster presentation. "Increase in emergency department turnaround time due to [CT] may worsen ED overcrowding."

Previous studies have shown that the positive predictive value of CT scans in patients with acute appendicitis was on a par with that of good history taking and physical exam alone, and that an increase in the use of CT from 1994 to 2000 was associated with a significant increase in ED waiting time, but no significant decrease in negative laparotomies, the authors noted.

Dr. Perry and colleagues asked whether the extra time involved in getting a CT scan for patients with suspected acute appendicitis could be associated not just with increased expense and radiation exposure, but also suboptimal clinical care. They conducted a retrospective chart review of all adults with suspected appendicitis during 2003.

Only those patients who went to the OR and were diagnosed with appendicitis were included in the analysis. Pathology reports were used to verify the operative report, and the patients' demographic and clinical characteristics were also collected.

The authors analyzed the data as proportions, and tested associations with chi-square and logistic regression to determine statistical significance at an alpha of 0.05.

They identified from all available records 140 adults ages 18 and older with a final pathology-confirmed appendicitis. There were a total of 16 (11%) perforations and an additional 10 (7%) gangrenous appendices, for a total of 26 (19%) complicated cases.

A total of 56 patients of the 140 patients (42%) had a CT done prior to operation. The authors found that CT scanning was associated with a significant increase in perforated or gangrenous appendicitis, with an unadjusted odds ratio of 2.5 (95% confidence interval, 1.0-6.0).

When the investigators adjusted for patient gender, race, and duration of symptoms of more than 48 hours, they found that CT was associated with a three-fold risk for a worse outcome (odds ratio 3.1, 95% CI, 1.2 to 8.1; P values not shown).

The investigators concluded that "CT scanning appears to be associated with a worse outcome in patients with appendicitis who present to the ED. Further studies need to explore this potentially harmful effect further and determine whether any benefit from lower negative laparotomy rates are sufficient to warrant performing CTs in suspected appendicitis."

They noted that the study was limited by its retrospective design, some missing chart data, some incomplete histories and physical exam data, and by uncertainties about why CT studies were ordered in some of the cases.

They are planning to conduct a randomized controlled study to explore further a possible association between CT and worse appendicitis outcomes.