Serial human chorionic gonadotropin determinations by fluoroimmunoassay for differentiation between intrauterine and ectopic gestation.

A new means for differentiation between ectopic and early intrauterine pregnancy--the human chorionic gonadotropin score--is described. The score relates the rate of serum hCG rise per day to the initial human chorionic gonadotropin level. The positive predictive value for ectopic pregnancy was 94.7%, based on human chorionic gonadotropin scores from 41 women with increasing human chorionic gonadotropin levels in the range of 10 to 4000 IU/L. The method may be useful for identification of ectopic pregnancy in a category of women in whom ultrasonography is of limited diagnostic value.