Presurgical imaging for appendicitis needed for young women, but not men

CHICAGO - Young males do not require imaging to accurately diagnosis acute appendicitis, but young women require imaging with ultrasound, according to a new evidence-based multimodality algorithm developed by researchers at Boston University Medical Campus in Massachusetts.

In an oral presentation Monday at the 90th scientific assembly and annual meeting of the Radiological Society of North America (RSNA), lead author Dr. Sarah Bixby said that clinical evaluation alone has a 92% accuracy rate in young males, thus "young men can be sent straight to surgery without imaging."

A similar accuracy, 92%, is associated with ultrasound evaluation in young women she said. But for older men and women or "very thin patients," imaging with computed tomography (CT) is the best choice, she said.

Pregnant women are generally a more difficult group to evaluate, and she noted that in the first or second trimester, ultrasound is a good choice for assessing abdominal pain. Later in pregnancy, however, magnetic resonance imaging is more reliable.

Dr. Bixby and colleagues developed the algorithm after analyzing data from 500 consecutive appendectomy patients: 295 men and 205 women. The age range of patients was 2 days to 86 years, and the mean age was 30. The patients were grouped by imaging modality or no imaging, and 27% (n = 135) had no imaging before surgery.

Ultrasound was used in 70 patients, and MRI was used in 15 patients. Most patients who had imaging studies were evaluated by CT (n = 280).

Eighty percent of the 135 patients who had surgery with no preoperative imaging had pathology-proven acute appendicitis, "but when we only consider men, the positive rate increases to 92%," Bixby said. Of the patients evaluated with ultrasound alone, 70% of the patients were women with a mean age of 19. Fifty-nine patients had ultrasound studies that indicated appendicitis, and "54 of these women or 92% had pathology-proven appendicitis," she said.

One hundred and fifty-one men and 129 women, mean age 33, had CT evaluation prior to surgery. The CT was positive for appendicitis in 260 patients (93%), and the appendix was inflamed in 252 (97%).

Among the 15 patients in the MRI group, 12 were positive. All the MRI patients were women and seven were pregnant. "In all cases the MR diagnosis was correct," Bixby said.

During the discussion, Dr. Claude Sirlin from the University of California, San Diego, cautioned about sending young men to surgery without imaging. "In the San Diego area, we have a significant number of HIV-positive young men, and I would be concerned about simply sending them to surgery on the basis of clinical evaluation," he said. He noted, too, that other conditions, including inflammatory bowel disease, can present with clinical symptoms very similar to acute appendix.

By Peggy Peck contributing writer
November 29, 2004

Related Reading

CT can be used to rule out appendicitis, October 11, 2004

Standard-dose no better than low-dose CT for diagnosing appendicitis, July 28, 2004

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