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) and its isoenzyme CPK- muscle brain (MB) in ectopic pregnancy (EP) in order to locate a simpler diagnostic approach for EP. MATERIALS AND METHODS: This was a prospective study that performed consecutive sampling for 20 months in two major hospitals in Isfahan, Iran. All pregnant patients in their first trimester of gestation that presented with complaints of vaginal bleeding, abdominal pain, or both enrolled in this study. Blood sampling was performed for laboratory analyses (CPK, CPK-MB). After their diagnosis was established, patients were put in either the EP or non-EP group. We used SPSS software version 10 for data analysis, diagnostic parameters were determined, and a relative operating 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 predictive value (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 the ROC 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 levels in EP, transvaginal ultrasound (TVS) is still the better diagnostic tool for EP.