Progesterone test could identify nonviable pregnancies

By Nikki Withers, medwireNews Reporter

A single progesterone measurement may be useful for predicting nonviable pregnancies in women with pain or bleeding when an ultrasound investigation proves to be inconclusive, say researchers.

The team found that a low concentration of progesterone (<3.2-6 ng/mL) ruled out a viable pregnancy in 99.2% of women.

However, the test was unable to distinguish women with an ectopic pregnancy from those with an early normal pregnancy or a miscarriage, and the authors say the test should not be used for this purpose.

Writing in the BMJ, Ioannis Gallos (University of Oxford, UK) and colleagues explain that a progesterone test has been proposed as a useful test to distinguish a viable pregnancy from a nonviable pregnancy.

To assess the diagnostic accuracy of such a test, the team reviewed data from 26 cohort studies that included a total of 9436 women with a pregnancy of less than 14 weeks' gestation. Seven of the studies included women with pain or bleeding and an inconclusive ultrasound assessment and 19 studies included women with the symptoms alone.

The researchers report that a single progesterone measurement is able to predict a nonviable pregnancy with a sensitivity of 74.6% and specificity of 98.4% in women with pain or bleeding and inconclusive ultrasound.

The median prevalence of a nonviable pregnancy was 73.2%, but increased to 99.2% if the progesterone level was low (<3.2-6 ng/mL)

The progesterone test was also able to predict a nonviable pregnancy in women with symptoms alone, with a sensitivity of 66.5% and specificity of 96.3% at a cutoff of 10 ng/mL.

The test could not, however, distinguish between an ectopic pregnancy and a miscarriage. Serial serum β human chorionic gonadotropin measurements are needed for that purpose, write the researchers.

They suggest that a progesterone test could be used in a complementary role for women presenting with pain or bleeding early in pregnancy.

"The test could be added to the existing algorithms for evaluation of early pregnancy, and its effect should be evaluated through a randomized trial comparing algorithms with and without serum progesterone," they conclude.

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