Creatine phosphokinase in ectopic pregnancy revisited: significant diagnostic value of its MB and MM isoenzyme fractions.

Objective: Although evidence on elevated creatine phosphokinase (CPK) as a tool for the diagnosis of ectopic pregnancy (EP) is rather conflictive, no previous study on CPK isoenzyme levels and their relative ratio was found in the literature.

Study Design: Forty women with EP, 20 with intrauterine (IU) abortive gestation, and 20 regular pregnant women (controls) were studied. Serum total CPK, CPK-MB, and CPK-MM levels were measured at the time of presentation and 24 hours after surgery. Relative operating characteristic (ROC) curves were plotted.

Results: Women with EP had significantly higher CPK concentrations and a significantly decreased CPK-MB relative ratio (CPK-MB%), compared with both women with IU abortive pregnancy and controls. The ROC curves demonstrated a significant discriminatory ability of both increased total CPK and decreased CPK-MB% ratio for the diagnosis of EP.

Conclusion: Determination of CPK isoenzyme fractions can significantly enhance the diagnostic value of total maternal CPK in the prediction of ectopic pregnancy.