Serum estradiol as an aid in the diagnosis of ectopic pregnancy

The value of serum beta-hCG measurement in the diagnosis of ectopic pregnancy is well established, and there have been recent studies on the use of serum progesterone levels. However, we have been unable to find any reports on the potential application of serum estradiol (E2) assays in the diagnosis of ectopic pregnancy. We therefore concurrently measured serum E2, progesterone, and beta-hCG in 100 women with ectopic pregnancies, as well as in 69 controls with normal intrauterine pregnancies and 36 women with threatened abortion. The mean (+/- standard deviation) E2 levels for ectopic-pregnancy patients, the normal controls, and the women with threatened abortion were 281.1 +/- 115.6, 788.2 +/- 45.5, and 788.8 +/- 40.6 pg/mL, respectively; the mean levels in the ectopic group were significantly different (P less than .0001) from those of the other two groups. All but one of the ectopic pregnancies had values below 650 pg/mL for E2 and 23 ng/mL for progesterone, and all but one of the normal intrauterine pregnancies had values above these levels. Our data suggest that the addition of the estradiol assay, with or without progesterone, to the early evaluation of patients suspected of having an ectopic pregnancy may be helpful in diagnosis.