Serial human chorionic gonadotrophin determination in the diagnosis of ectopic pregnancy.

Serial human chorionic gonadotrophin (HCG) determinations were made in 21 patients with ectopic pregnancy (EUP) and in 29 patients with early intrauterine pregnancy (IUP) to examine the increase in HCG values. The median slope of the HCG rise for the patients with EUP was 116 IU/1/2 days and 4,220 IU/1/2 days in patients with IUP. The slopes were significantly different (p < 0.05). Using a discrimination limit of 980 IU/1/2 days, the predictive value of a slope below this limit was 90% in EUP compared to the control group of intrauterine pregnancies. Determination of the slope of HCG rise may be of value in early recognition of ectopic pregnancy in patients with increasing HCG levels below the ultrasonographic discriminatory zone. An international agreement on discrimination limits and unity of HCG algorithms is suggested.