Ultrasound finding	Normal early pregnancy	Suspicious for early pregnancy loss*	Diagnostic of early pregnancy loss
Gestational sac (measured by mean sac diameter)	Appears four to five weeks after last menstrual period	Mean sac diameter of 16 to 24 mm and no embryo Absence of embryo with cardiac activity seven to 13 days after ultrasonography shows gestational sac without yolk sac Small gestational sac relative to size of embryo (< 5 mm difference between mean sac diameter and crown-rump length)	Mean sac diameter ≥ 25 mm and no embryo Absence of embryo with cardiac activity ≥ 2 weeks after ultrasonography shows gestational sac without yolk sac
Yolk sac	Appears 5.5 weeks after last menstrual period	Absence of embryo with cardiac activity seven to 10 days after ultrasonography shows gestational sac and yolk sac Enlarged yolk sac (> 7 mm)	Absence of embryo withcardiac activity ≥ 11 days after ultrasonography shows gestational sac and yolk sac
Embryo (measured by crown-rump length and embryonic cardiac activity)	Appears six weeks after last menstrual period; embryonic cardiac activity appears at 6.5 weeks	Crown-rump length < 7 mm and no embryonic cardiac activity Absence of embryo ≥ 6 weeks after last menstrual period Empty amnion (amnion seen adjacent to yolk sac with no visible embryo) Embryonic heartbeat ≤ 85 beats per minute	Crown-rump length ≥ 7 mm and no embryonic cardiac activity