Failed early pregnancy

Changed by Henry Knipe, 18 Jun 2015

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Failed early pregnancy refers to the death of the embryo and therefore, miscarriage. The most common cause of embryonic death is a chromosomal abnormality.

Radiographic assessment

Ultrasound

Findings diagnostic of pregnancy failure

crown-rump length (CRL) of ≥7 mm and no heartbeat
mean sac diameter (MSD) of ≥25 mm and no embryo
absence of embryo with heartbeat ≥2 weeks after a scan that showed a gestational sac without a yolk sac
absence of embryo with heartbeat ≥11 days after a scan that showed a gestational sac with a yolk sac

Findings suspicious but not diagnostic of pregnancy failure

crown-rump length (CRL) of <7 mm and no heartbeat
mean sac diameter (MSD) of 16-24 mm and no embryo
absence of embryo with heartbeat 7-13 days after a scan that showed a gestational sac without a yolk sac
absence of embryo with heartbeat 7-10 days after a scan that showed a gestational sac with a yolk sac
absence of embryo ≥ 6 weeks after last menstrual period
amnion seen adjacent to yolk sac, with no visible embryo (empty amnion sign)
enlarged yolk sac (>7 mm)
small gestational sac in relation to the size of the embryo (<5 mm difference between mean sac diameter and crown-rump length)
large amniotic cavity (expanded amnion sign)

Practical points

When there are findings suspicious for pregnancy failure, follow-up ultrasonography at 7-10 days to assess the pregnancy for viability is generally appropriate.