Canada: Thirty percent of pregnancies are complicated by pain and bleeding, raising concerns for viability. A recent study in the Canadian Journal of Emergency Medicine has found that a single progesterone level can give clinically helpful prognostic information on pregnancy viability during the first trimester in pregnant patients with miscarriage symptoms.
The study showed that more than nine out of ten patients with < 6.3 ng/mL level will have a diagnosis of a non-viable pregnancy, and similarly, more than nine out of ten patients with a level ≥ 20–25 ng/mL will have a confirmed viable pregnancy.

Bleeding and pain complicate 30% of early pregnancies, increasing concern for viability, and an estimated 15–20% of pregnancies end in miscarriage. These symptoms can be early signs of ectopic pregnancy or miscarriage, which are concerning and challenging both to physicians and patients. Challenges include the inability to provide prognostic information at the point of care and the prolonged wait time to discover pregnancy viability.
Against the above background, a research team led by Bahareh Ghaedi, Ottawa Hospital Research Institute, ON, Ottawa, Canada, aimed to investigate the diagnostic ability of a single serum progesterone level for assessing pregnancy viability among symptomatic patients.
For this purpose, the researchers conducted a predefined literature search in online databases for studies that enrolled patients in the first trimester with measured progesterone, miscarriage symptoms, and reported pregnancy viability from inception till July 2020. The researchers extracted data for progesterone threshold levels, two × two tables, and viability. Summary estimates were collected for specificity, sensitivity, Diagnostic Odds Ratio (DOR), and predictive values at given prevalence rates.

The researchers reported the following findings:
Fifty-four publications were identified. A total of 15,878 patients were enrolled, of whom 49.5% were confirmed to have a viable pregnancy, and 50.5% had confirmed non-viable pregnancy.
The cut-off value of progesterone varied from 3.2 to 25 ng/mL (20.034–79.5 nmol/L).
Performance of the following progesterone cut-off categories was evaluated: < 6.3, 6.3–12.6, 12.7–19.9, and 20–25 ng/mL.
For detecting non-viable pregnancy, progesterone with cut-off < 6.3 ng/mL had specificity 99.2%, sensitivity 73.1%, and DOR 322.0, and cut-off category 20–25 ng/mL had specificity 75%, sensitivity 91.3%, and DOR 31.4.
To conclude, a single progesterone level provides clinically helpful prognostic details on pregnancy viability.
"More than 90% of patients with < 6.3 ng/mL level will have a diagbosis of non-viable pregnancy, and more than 90% of patients with a level ≥ 20–25 ng/mL will have a confirmed viable pregnancy," they wrote.
Reference:
Ghaedi, B., Cheng, W., Ameri, S. et al. Performance of single serum progesterone in the evaluation of symptomatic first-trimester pregnant patients: a systematic review and meta-analysis. Can J Emerg Med (2022). https://doi.org/10.1007/s43678-022-00332-x