Contrast ups CT sensitivity for acute appendicitis

In the diagnosis of acute appendicitis in adult ED patients, contrast-enhanced CT (CCT) has a significantly higher diagnostic sensitivity than non-contrast CT, according to a study published in the January issue of Academic Radiology.

The study also indicated that CCT could ease the burden on emergency physicians or radiologists by making appendixes easier to identify.

“In today's crowded EDs, the difficulty level and consuming time of physicians' interpretations would influence patients' length of stay or disposition, and the use of hospital resources,” wrote authors Yu-Hui Chiu, MD, of Wan-Fang Hospital, Taipei Medical University, Taiwan.

Chiu and colleagues retrospectively tested the necessity of intravenous contrast medium in 100 ED patients with clinical suspicion of acute appendicitis due to right lower quadrant abdominal pain. Both CCT and non-contrast CT scans were performed for each patient, with findings recorded separately and evaluated without knowledge of the patient’s final diagnosis.

Forty-two of the patients had acute appendicitis. Results showed that CCT offered significant increases over non-contrast CT for sensitivity (100 percent vs. 90.5 percent) and negative predictive value (100 percent vs. 93.5 percent). The authors reported that the appendix was easier to detect on CCT than on non-contrast enhanced images.

Despite these gains, there was not a significant difference between methods for overall accuracy.

The authors noted that many intra-abdominal diseases clinically mimic acute appendicitis, and in the current study, gastrointestinal tract diseases accounted for the majority of non-appendicitis diagnoses. Women of child-bearing age are also at great risk of misdiagnosis, with obstetric and gynecologic diseases representing more than 20 percent of non-appendicitis diagnoses.

“In patients presenting with abdominal pain suspecting for [acute appendicitis], the ultimate goal of CT imaging is to make a prompt diagnosis and reduce the delay of appendectomy,” wrote Chiu and colleagues. “We think performing CT with intravenous contrast material would be still necessary for patients suspected [acute appendicitis].”