Assessment of The Diagnostic Capability of Serum Creatine Phosphokinase and Its Isoenzyme in Ectopic Pregnancy

Background: Our goal was to assess the diagnostic value of creatine phosphokinase (CPK) andits isoenzyme CPK- muscle brain (MB) in ectopic pregnancy (EP) in order to locate a simplerdiagnostic approach for EP.Materials and Methods: This was a prospective study that performed consecutive sampling for20 months in two major hospitals in Isfahan, Iran. All pregnant patients in their first trimester ofgestation that presented with complaints of vaginal bleeding, abdominal pain, or both enrolled inthis study. Blood sampling was performed for laboratory analyses (CPK, CPK-MB). After theirdiagnosis was established, patients were put in either the EP or non-EP group. We used SPSSsoftware version 10 for data analysis, diagnostic parameters were determined, and a relativeoperating characteristic (ROC) curve was plotted for each biochemical marker.Results: A total of 106 patients, 53 in the EP group and 53 in the non-EP group enrolled in this study.The results for CPK were as follows: sensitivity (69.81%), specificity (64.15%), positive predictivevalue (PPV; 66.07%), negative predictive value (NPV; 68%), positive likelihood ratio (PLR) (1.95),and negative likelihood ratio (NLR) (0.49). The results for CPK-MB were: sensitivity (71.7%),specificity (56.6%), PPV (62.29%), NPV (66.7%), PLR (1.65), and NLR (0.5). The area under theROC curve for CPK was 0.692 and for CPK-MB it was 0.647.Conclusion: Although we have observed a significant elevation in CPK and CPK-MB serum levelsin EP, transvaginal ultrasound (TVS) is still the better diagnostic tool for EP.