FAILURE OF TC-99M HEXAMETHYLPROPYLENE AMINE OXIME LEUKOCYTE SCINTIGRAPHY IN THE EVALUATION OF CHILDREN WITH SUSPECTED APPENDICITIS

To determine the accuracy and reliability of a labeled leukocyte imagi ng technique in the early diagnosis of pediatric appendicitis, we pros pectively studied patients presenting to the pediatric emergency depar tment with abdominal pain suggestive of appendicitis, Patients schedul ed for urgent laparotomy were excluded, as were postmenarchal females, Blinded interpretations by two independent radiologists were compared with surgical findings, if managed operatively, or with discharge dia gnoses and three week follow-up, if managed medically. Twenty-three ch ildren;underwent technetium-99m hexamethylpropylene amine oxime (HMPAO ) leukocyte scintigraphy, Seven had pathologically proven appendicitis , with false negative interpretations made in three and five cases by the two radiologists, Sixteen patients had prompt resolution of sympto ms; however, scintigraphic abnormalities were identified in 10 and sev en cases by the two radiologists, Resulting sensitivity, depending on the individual reader, ranged from 29 to 57%, with specificity 38 to 5 6%, positive predictive value 22 to 29%, negative predictive value 64 to 67%, and accuracy 43 to 48%. Interrater reliability for agreement o n the scintigraphic diagnosis of appendicitis was poor (kappa = 0.38). Technetium-99m HMPAO leukocyte scintigraphy was neither accurate nor reliable as a diagnostic tool in a subgroup of pediatric patients with an initial clinical presentation equivocal for appendicitis, This fin ding contradicts previously published experience using similar scintig raphic techniques.