AEM: CT use for appendicitis soars in the ED

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The percentage of patients with appendicitis who underwent a CT in the emergency department (ED) climbed from 6.3 percent among adults in 1996 to 69 percent in 2006 and from 0 percent among children to 59.8 percent in the same interval, according to a study published in the August issue of Annals of Emergency Medicine.

CT is often used in the evaluation of appendicitis in the ED. To better understand trends in the use of CT in ED visits in which appendicitis was diagnosed, researchers completed an analysis of the National Hospital Ambulatory Medical Care Survey (NHAMCS) database for 1992 through 2006.

The sample comprised 447,011 ED visits from which 1,088 visits with a diagnosis of appendicitis were analyzed. Of these visits, 30.9 percent represented pediatric patients and 69.1 percent were adult patients.

CT utilization spiked for both groups during the decade, while appendicitis diagnoses as a percentage of ED visits increased 1.9 percentage points for adults from 1992 to 2006 and decreased 1.2 percentage points for children in the same time period.

“The use of CT imaging in every patient being considered for a diagnosis of appendicitis is not standard of care. The use of clinical findings to risk-stratify patients and guide decisions about further testing has been advocated, with no mention that CT should be the modality of choice if imaging is indicated,” wrote Daniel S. Tsze, MD, MPH, from the division of pediatric emergency medicine and department of emergency medicine at Warren Alpert Medical School of Brown University in Providence, R.I.

Tsze et al referred to previous studies supporting the use of ultrasound in the evaluation of appendicitis and noted that clinical evaluation and selective imaging can deliver low rates of negative appendectomy results and appendiceal perforation in children.

In other studies, the researchers also found that adult patients diagnosed by clinical evaluation alone had shorter time to the operating room and no difference in perforation rates than those who underwent CT.

The authors offered several reasons behind the upsurge in CT in the evaluation of appendicitis. It provides high sensitivity and specificity. Because appendicitis has a high incidence of atypical presentation, physicians welcome the high diagnostic accuracy of CT. In addition, appendicitis is a common diagnosis listed in malpractice claims.

Tsze and colleagues acknowledged the lack of data regarding the percentage of patients who undergo CT for appendicitis evaluation with subsequent negative results.

Some single center studies have reported decreases in negative appendectomy result rates and fewer appendiceal perforations in the last decade. However, the results cannot definitively be linked to CT nor are they generalizable because the studies were conducted at academic medical centers.

“There may be a potential benefit that increased CT use confers on patients with, and being evaluated for, appendicitis,” wrote Tsze and colleagues. However, increased malignancies stemming from radiation exposure represent a risk. Ultrasound avoids such risks, but the limited data about ultrasound in the NHAMC databases did not permit an analysis, the researchers noted.