CT, ultrasound may save women from appendectomy

September 1, 2006

Routine imaging of women who have suspected appendicitis could avoid need for costly procedure

All women of reproductive age with suspected appendicitis should be routinely imaged with ultrasound, CT, or both if clinically necessary prior to surgery, according to Dr. R. Brooke Jeffrey, a professor of radiology at Stanford, during the Stanford Multidetector-Row CT symposium in San Francisco.

In other patient groups, imaging with ultrasound or CT should be used selectively to assess complex cases of suspected appendicitis, he said.

Gynecologic conditions can often mimic appendicitis. Clinical assessment is tricky and the risk of performing unnecessary surgery is higher in this population. Imaging can help provide accurate assessment, discharge patients earlier, and avoid subjecting women to the risks of needless surgery, Jeffrey said.

"The single most important benefit of imaging is reducing unnecessary surgery. Eliminating negative appendectomy should be one of our primary goals," Jeffrey said.

A large three-year retrospective study conducted by Stanford researchers in 2002 found that imaging with CT and ultrasound helped reduce the number of unnecessary appendectomies in women over 16 years of age. In this group, the negative appendectomy rate was 28% for those who went straight to surgery. The rate was only 5% for those who underwent CT first and 4% for those who had ultrasound.

Which study to use, CT or ultrasound, is a matter of institutional preference. There has been a shift away from ultrasound to CT in suspected appendicitis, and now only 20% of cases are imaged with ultrasound. Ultrasound's overall accuracy is lower than that of CT, with a sensitivity of about 85% versus about 95% for CT. In addition, the normal appendix can be difficult to visualize with ultrasound.

"We are now in the era of CT, with high-resolution volumetric scanning," Jeffrey said.

Despite this shift in practice, however, it's important to remember the value of radiation-free ultrasound, particularly in women's imaging, he said. "Ultrasound has tremendous advantages. It's safe for use in pregnant patients. It's an interactive real-time technique," he said.

When performing ultrasound imaging of patients with abdominal pain, it's important to ask patients to point out exactly where the pain is and scan that area. Sometimes, more than one imaging study is needed.

"Ultrasound and CT are complementary, and we should never be afraid to use both if necessary to make a diagnosis to avoid a $25,000 negative appendectomy. I have no compunction about using both," Jeffrey said.