The utility of maternal creatine kinase in the evaluation of ectopic pregnancy

This investigation was designed to evaluate the utility of maternal creatin e phosphokinase (CPK) in predicting the presence of an ectopic pregnancy (E P) in an emergency department (ED) setting. Twenty-one patients with the di agnosis of EP were randomly matched (1:1) with pregnant patients who subseq uently ruled-out for EP, Serum CPK values at presentation were compared bet ween the groups using two tailed ANOVA, odds ratio, and frequency tables we re generated using our a priori hypothesis that a serum CPK of >70 mlU/dL m ay be useful as a predictor of EP, The mean serum CPK was 118 mlU/dL in the EP group and 64 mlU/dL in the non EP group (P <.0031). Controlling for age , race, and gestational age, there was an association between elevated seru m CPK and EP in our study population (with an odds ratio of 6.5). The categ orical evaluation (with 95% confidence interval [CII) of CPK (>70 mlU/dL) a s a predictor of EP follows: sensitivity - 100% (80.8 to 100); specificity 61.9% (38.7 to 81); PV(+) - 72.4% (52.5 to 88.6); PV(-) - 100% (71.7 to 100 ). We therefore conclude that a CPK level >70 mlU/dL may serve as an import ant adjuvant diagnostic tool in ruling out EP, (Am J Emerg Med 2000;18:685- 687 Copyright (C) 2000 by W.B. Saunders Company).