This easy-to-calculate score may prove useful for avoiding CT test in 25% of patients seeking surgical abortion.

First trimester nonviable pregnancy is established with gestational sac mean diameter and embryo crown-rump length. Mean sac diameter≥25mm without embryo (LE2) or embryo crown-rump length≥7mm without heartbeat (LE2) by transvaginal sonography allows to diagnose pregnancy failure. Intrauterine pregnancy of uncertain viability is defined by intra-uterine gestational sac without embryo with heartbeat or without pregnancy diagnosis failure and requires a new transvaginal sonography. The delay for this second sonography depends on the aspect of intrauterine picture (i.e. presence of yolk sac or not, presence of embryo or not) (LE4). Human chorionic gonadotropin (hCG) and progesterone are useful for pregnancy of unknown location (i.e. no gestational sac at transvaginal sonography): hCG ratio<15% between two-day serum samples when first hCG is<2000UI/mL (LE2) or low serum progesterone level (<3.2ng/mL) (LE2) exclude viable intrauterine pregnancy. There is not known prevention strategy for threatened miscarriage.