Evaluating cut-off levels for progesterone, β human chorionic gonadotropin and β human chorionic gonadotropin ratio to exclude pregnancy viability in women with a pregnancy of unknown location: A prospective multicenter cohort study.

Cut-off levels for βhCG, βhCG ratio, and progesterone are not safe to be used clinically to exclude viability in early pregnancy. Although βhCG ratio and progesterone have slightly better performance in comparison, single βhCG used in this manner is highly unreliable.