Rapid diagnosis of early ectopic pregnancy in an emergency gynaecology service--are measurements of progesterone, intact and free beta human chorionic gonadotrophin helpful?

The clinical usefulness of measuring serum concentrations of progesterone, human chorionic gonadotrophin (HCG) and the free beta-subunit of HCG in distinguishing between early viable and non-viable pregnancy, before an accurate ultrasound diagnosis is possible, was evaluated in a prospective study of patients presenting to our emergency gynaecology service with a clinical suspicion of ectopic pregnancy. Patients were selected on the basis of initial HCG concentrations; samples with HCG 25-10,000 IU/l were later analysed for progesterone and free beta HCG. Of the 181 patients studied, 38 (21%) had an ectopic pregnancy, 108 (60%) had a spontaneous abortion and 35 (19%) had a viable intra-uterine pregnancy. Concentrations of HCG and free beta HCG in the group with viable pregnancies were significantly higher than in the group with ectopic pregnancy (P < 0.001) and than those destined to miscarry (P < 0.01). Progesterone concentrations were also significantly higher in the viable versus the ectopic and the spontaneous abortion groups (P < 0.001 in each case). Despite these highly significant differences there was a degree of overlap such that it was impossible to devise a cut-off level for any hormone analysed, either singly or in combination, which would offer a clinically useful predictor of outcome.