Per New England Journal of Medicine Guidelines (PM Doubilet et al, 2013), findings diagnostic of a pregnancy failure are:

1. Crown-rump length > 7mm and no heartbeat

2. Mean sac diameter of >25mm and no embryo

3. Absence of embryo with heartbeat >2 weeks after a scan that showed a gestational sac without a yolk sac

4. Absence of embryo with heartbeat >11 days after a scan that showed a gestational sac with a yolk sac