Comparison between technetium-99m hexamethylpropyleneamineoxide labeled white blood cell abdomen scan and abdominal sonography to detect appendicitis in female patients with an atypical clinical presentation.

BACKGROUND/AIMS: Acute appendicitis is a clinically challenging surgical disease which is particularly difficult to diagnosis in women. An atypical presentation is a major obstacle to quickly diagnose acute appendicitis.

METHODOLOGY: Fifty female patients with acute abdomen pain who were suspected of having appendicitis, but who had atypical findings were included in this study. After an intravenous injection of technetium-99m hexamethylpropyleneamineoxide (Tc-99m HMPAO) labeled white blood cells, serial anterior abdomen-pelvis images at 30 min, 60 min, 120 min and 240 min were obtained using a gamma camera. Meanwhile, at the point of maximal tenderness, abdominal sonography was performed with a graded compression technique for both longitudinal and transverse images.

RESULTS

Thirty-two patients received a laparotomy for surgical and pathological diagnoses. The remaining 18 patients did not receive operations and showed no evidence of appendicitis after at least a one-month follow-up period. Two patients had false-positive white blood cell scan findings and 2 patients had false-negative white blood cell scan findings. The overall sensitivity, specificity, and accuracy for white blood cell scans in diagnosing appendicitis was 93.3%, 90.0%, 92.0%, respectively. One patient had false-positive abdominal sonographic finding and 5 patients had false-negative abdominal sonographic findings. The overall sensitivity, specificity, and accuracy for abdominal sonography scans in diagnosing appendicitis were 83.3%, 95.0%, and 88.0%, respectively.

CONCLUSIONS

The Tc-99m HMPAO white blood cell scan provides a more sensitive and accurate method for the diagnosis of appendicitis in female patients with equivocal clinical presentation when compared with abdominal sonography.