Symptoms and Diagnostic Criteria for Miscarriage

Primary Warning Signs

Painful vaginal bleeding in early pregnancy suggests possible miscarriage in progress or other complications such as ectopic pregnancy, according to the American College of Radiology 1
The combination of pain and bleeding is more concerning than bleeding alone, as indicated by the American College of Radiology 1

Embryonic crown-rump length (CRL) less than 7 mm with no cardiac activity is a concerning feature, as reported by Radiology 2
Mean sac diameter (MSD) 16-24 mm with no embryo visualized is a concerning feature, as reported by Radiology 2
Absent embryo 6 or more weeks after last menstrual period is a concerning feature, as reported by Radiology 2
Small gestational sac compared with embryo size is a concerning feature, according to the American College of Radiology 3
Abnormal size or shape of the yolk sac is a concerning feature, according to the American College of Radiology 3
Embryonic bradycardia (slow heart rate) is a concerning feature, according to the American College of Radiology 3
CRL 7 mm or greater with no cardiac activity confirms embryonic demise, as reported by Radiology and the American College of Radiology 2, 3
MSD 25 mm or greater with no embryo confirms nonviable pregnancy, as reported by Radiology and the American College of Radiology 2, 3
Products of conception visible on examination is a diagnostic feature, as reported by the Annals of Emergency Medicine 4

Ectopic pregnancy must be carefully excluded when intrauterine pregnancy is not definitively identified, according to the American College of Radiology 3
If initial transvaginal ultrasound shows MSD less than 25 mm with a yolk sac but no embryo, nonviable pregnancy can be diagnosed if there is no embryonic cardiac activity 11 or more days later, as indicated by the American College of Radiology 3
If initial scan shows gestational sac without yolk sac (MSD less than 25 mm), nonviable pregnancy can be diagnosed if no cardiac activity is present 14 or more days later, as indicated by the American College of Radiology 3