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

Background/aims: Diagnosing acute appendicitis in children with equivocal signs and symptoms is usually difficult. The usual approach to the patient is hospital observation and frequent reexamination. However, many surgeons are reluctant to delay surgery because of the risk of perforation and a negative laparotomy. The aim of this study is to assess and compare the value of the Tc-99m HMPAO (technetium-99m hexamethylpropyleneamineoxide) labeled white blood cell abdomen scan and abdominal sonography in the diagnosis of acute appendicitis in children with an atypical clinical presentation.

Methodology: Forty children with acute abdomen and possible acute appendicitis but atypical findings were included in this study. After an intravenous injection of Tc-99m HMPAO white blood cells, serial anterior abdomen scans 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-three children received operation for surgical and pathological diagnoses. The other 17 children did not receive operation but follow-up of at least a one-month period. The overall sensitivity, specificity, and accuracy of Tc-99m HMPAO white blood cell scan to diagnose acute appendicitis in children with atypical findings is 96.7%, 80.0%, and 90.0%, respectively. The overall sensitivity, specificity, and accuracy for abdominal sonography is 86.6%, 90.0%, and 88.0%, respectively.

Conclusions: The Tc-99m HMPAO white blood cell abdomen scan provides a more sensitive and accurate method for the diagnosis of appendicitis in children with atypical clinical presentation when compared with abdominal sonography.