Vaginal bleeding and abdominal pain are seen in about 30-40% of women in the first trimester. of pregnancy. Most women with those symptoms will undergo a transvaginal ultrasound to explore the problem, and if a fetal heartbeat is seen that is reassuring of a low chance of a miscarriage. But when the ultrasound is unclear that might not be enough to determine whether the pregnancy is viable.
A study published in the British Medical Journal showed that a single blood progesterone test may help women who have a threatened miscarriage with bleeding and/or pain and an unclear sonogram find out early in pregnancy whether they are miscarrying or have an ectopic pregnancy.
A progesterone test has been proposed to help make the diagnosis because low levels are associated with miscarriages and ectopic pregnancies.
This study included data from 26 studies that included a total of 9,436 women with a pregnancy of fewer than 14 weeks gestation. The progesterone blood test below 10 ng/mL predicted nonviable pregnancies with a pooled sensitivity of 66.5% and a specificity of 96.3%. The median prevalence of nonviable pregnancy was 62.9%, a rate that increased to 96.8% when the progesterone level was below 10 ng/mL and dropped to 37.2% when the progesterone level was above the cutoff. It showed that the risk of a nonviable pregnancy was 99.2% when progesterone levels were below the cutoff and 44.8% when they were above the cutoff. In this study, a single blood progesterone test with a threshold of 3.2 to 6 ng/mL predicted a pregnancy that ended in a miscarriage with a sensitivity of 74.6% and a specificity of 98.4%. The progesterone test could not, however, distinguish between an ectopic pregnancy and a miscarriage. Serial serum β human chorionic gonadotropin measurements are needed for that purpose.
The researchers said that a progesterone test could serve in a complementary role for women presenting with pain or bleeding early in pregnancy.
Verhaegen J, et al "Accuracy of single progesterone test to predict early pregnancy outcome in women with pain or bleeding: meta-analysis of cohort studies" BMJ 2012;