Tc-99m HMPAO-labeled WBC scans to detect appendicitis in women.

Fifty female patients with acute abdomen and suspected appendicitis but atypical findings were included in this study. After intravenous injection of Tc-99m HMPAO-labeled WBCs, serial anterior abdominal/pelvic images at 30, 60, 120, and 240 minutes were obtained by a gamma camera. Any abnormal localization of WBC accumulation in the right lower quadrant of the abdomen with equal to or greater than bone marrow activity was considered as a positive scan. Thirty patients had positive WBC scans and underwent laparotomy, 28 had proven appendicitis, and 2 were not related to appendicitis. Twenty patients had negative WBC scans, 2 patients underwent laparotomy and were proved to have appendicitis. The remaining 18 patients did not undergo surgery and revealed no evidence of appendicitis after follow-up. The overall sensitivity, specificity, accuracy, and positive and negative predictive values for WBC scans to diagnose appendicitis is 93.3%, 90.0%, 92.0%, 93.3%, and 90.0%, respectively. In conclusion, Tc-99m HMPAO-labeled WBC imaging provides a rapid and highly accurate method for diagnosis of appendicitis in female patients with equivocal clinical examinations.