Evaluation of serum creatine phosphokinase in diagnosis of tubal ectopic pregnancy compared with intrauterine pregnancy and threatened abortion

Background: Vaginal sonograghy and serial β-hCG are the most common diagnostic methods for ectopic pregnancy but about 50% of cases are initially misdiagnosed. In tubal pregnancy the zygote lies next to the muscular layer, and this invasion causes an increase in creatine phosphokinase (CPK) in blood.
Objective: assessment of CPK and its isoenzyme CPK-MB as a diagnostic marker for tubal pregnancy.
Materials and Methods: In this case-control study, 111 women between 16-40 years in first-trimester pregnancy admitted to emergency ward of Rasht Alzahra hospital with abdominal pain or vaginal bleeding were included and according to sonography and βhCG divided into 3 groups (N=37): tubal pregnancy (1), threatened abortion (2) and normal pregnancy (3). Blood samples were taken for totalCPK and CPK-MB before any invasive procedure.
Results: Mean total CPK level were 96.27±63.9 u/lit (group 1), 55.37±14.1 u/lit (group 2) and 48.94±19.2 u/lit (group 3) and was significantly higher in tubal pregnancy compared to other groups. Mean CPK-MB levels in 3 groups were 15.62±5.2 u/lit, 17.32±6.9 u/lit, and 15.1±4.7 u/lit, respectively which was not significant.
Conclusion: It seems that determination of total CPK can enhance the diagnostic value of tubal pregnancy.

Keywords
Creatine phosphokinase, Tubal ectopic pregnancy, Threatened abortion, Intrautine pregnancy.