SERUM CREATINE-KINASE IS AN UNRELIABLE PREDICTOR OF ECTOPIC PREGNANCY

Objective: To compare serum creatine kinase (CK) values ire patients w ith ectopic pregnancy vs patients with threatened miscarriage or norma l pregnancy. Methods: An observational case-control study was performe d at an urban teaching hospital. Pregnant women with a quantitative be ta-hCG obtained for suspicion of ectopic pregnancy were evaluated. Exc luded were cases with recent trauma, SM Injections, surgery, or histor y of heart, liver, or muscle disease. The serum beta-hCG and CK values were recorded and compared between groups with 1-way ANOVA and Tukey' s multiple comparison procedure at the overall 0.05 level. Results: Th e 15 ectopic, 28 threatened miscarriage, and 21 normal pregnancy cases were of similar gestational ages (p = 0.2), ranging from 3 to 12 week s, Although the CK values For ectopic pregnancy (88.8 +/- 33.6 IU/ L) exceeded those for threatened miscarriage (65.9 +/- 59.0 IU/L) and nor mal pregnancy (56.0 +/- 38.1 U/L) (p = 0.02), there was significant ov erlap between groups, CK values were at or above a cutoff of 74 IU/L, in 80% (95% confidence interval: 52-96%) of ectopic pregnancies, 25% ( 11-45%) of threatened miscarriages, and 14% (3-36%) of normal pregnanc ies. Conclusions: Although the ectopic pregnancy population is charact erized by a higher mean CK than are patients with threatened miscarria ge or a normal pregnancy, a significant overlap in CK values makes use of this serum marker unreliable for detecting ectopic pregnancy.