Accuracy of single measurements of pregnancy-associated plasma protein-A, human chorionic gonadotropin and progesterone in the diagnosis of early pregnancy failure.

Background: Circulating human chorionic gonadotropin (hCG) and progesterone are commonly used as markers of abnormal pregnancies. Previous studies have shown that pregnancy-associated plasma protein-A (PAPP-A) was also depressed in extrauterine pregnancies (EUP). Previously, PAPP-A was measured with polyclonal antibodies which were later shown to recognise also the pro-form of major basic protein (pro-MBP).

Objective: To evaluate the clinical usefulness of PAPP-A measurements in early pregnancy.

Study Design: Circulating PAPP-A, hCG and progesterone were measured in patients with EUP (n=68), abnormal intrauterine pregnancies (abIUP, n=31) and normal intrauterine pregnancies (nIUP, n=72). Gestational age was 30-70 days from the last menstruation.

Results: For PAPP-A and hCG, a steep increase was observed from day 30 after last menstrual period onwards, this increase being much less important for abIUP and EUP. The values of PAPP-A and hCG were significantly decreased in abIUP and EUP, from 42 days after LMP onwards. There were no significant differences between abIUP and EUP. Progesterone concentration does not vary with amenorrhoea and was significantly lower in abIUP and EUP. Values in abIUP were significantly (P=0.02) lower compared with EUP for amenorrhoea above 42 days. ROC curves were constructed for amenorrhoea above 42 days. For a specificity of 99%, the sensitivity of PAPP-A, hCG and progesterone were 64.5, 93.3 and 76%, respectively. The threshold values were 14.3mIU/l, 10,400IU/l and 10.1ng/ml for PAPP-A, hCG and progesterone.

Conclusion: We confirm the decrease of PAPP-A concentrations in pregnancy failure, but hCG and progesterone remain the best clinical tools.