Evaluation of leukemia inhibitory factor as a marker of ectopic pregnancy

OBJECTIVE: Our purpose was to determine the utility of measuring serum leuk emia inhibitory factor, a cytokine expressed in the process of pregnancy im plantation, for the diagnosis of ectopic pregnancy. STUDY DESIGN: Serum samples from 40 patients with positive serum quantitati ve beta -human chorionic gonadotropin levels were used for leukemia inhibit ory factor determination. The serum leukemia inhibitory factor concentratio n was determined by enzyme-linked immunosorbent assay in the following 4 gr oups: (1) normal intrauterine pregnancies, (2) threatened abortions, (3) sp ontaneous abortions, and (4) ectopic pregnancies. RESULTS: Ail patients had detectable concentrations of leukemia inhibitory factor in serum, ranging from 2.44 to 8.25 pg/mL. Mean leukemia inhibitory factor concentrations for ectopic pregnancy were significantly lower (P < . 05) than those of both the spontaneous abortion and threatened abortion gro ups by 1-way analysis of variance. When a cutoff point of serum leukemia in hibitory factor < 6.2 pg/mL is assigned as diagnostic of ectopic pregnancy, leukemia inhibitory factor in patients with ectopic pregnancies versus all other groups predicted ectopic pregnancy with a sensitivity of 73%, specif icity of 72%, positive predictive value of 50%, and negative predictive val ue of 88%. CONCLUSION: Serum leukemia inhibitory factor concentration is lowest in pat ients with ectopic pregnancy. A cutoff point of 6.2 pg/mL maximizes the sen sitivity and specificity of the lest; however, it is not sufficiently discr iminatory to be used clinically for the diagnosis of ectopic pregnancy.