SERUM CREATINE-KINASE DOES NOT PREDICT ECTOPIC PREGNANCY

Objective: To evaluate the discriminatory ability of maternal serum cr eatine kinase (SCK) as a test for ectopic pregnancy (EP), Design: Seru m creatine kinase concentrations were obtained prospectively from symp tomatic patients being evaluated for early abnormal pregnancy. Serum c reatine kinase concentrations from all patients and from a subset of t hese patients with maternal serum beta-hCG concentrations <6,500 mIU/m L (conversion factor to SI unit, 1.00) were analyzed with descriptive statistics, receiver operator characteristic (ROC) curve analysis, and calculations of predictive values. Setting: A university hospital eme rgency room. Patients: Fifty-six patients with intrauterine gestations (25 with beta-hCG concentrations <6,500 mIU/mL) and 23 patients with EP (20 with beta-hCG concentrations <6,500 mIU/mL) were studied. Resul ts: For all patients and the subgroup with beta-hCG concentrations <6, 500 mIU/mL, mean SCK levels were not significantly different between e ctopic and intrauterine gestations. For all patients and the subgroup with beta-hCG concentrations <6,500 mIU/mL, the areas under the ROC cu rves did not demonstrate discriminatory ability of the SCK test. The h ighest positive predictive value of an elevated SCK for EP was 52% usi ng the SCK concentration of 70 Un, and this was seen in the subgroup o f patients with beta-hCG values <6,500 mIU/mL. Conclusions: Maternal S CK concentrations do not reliably predict EP.