how doctors diagnose miscarriage

Pelvic exam. Your health care provider might check to see if your cervix has begun to dilate.
Ultrasound. During an ultrasound, your health care provider will check for a fetal heartbeat and determine if the embryo is developing normally. If a diagnosis can’t be made, you might need to have another ultrasound in about a week.

Blood tests. Your health care provider might check the level of the pregnancy hormone, human chorionic gonadotropin (HCG), in your blood and compare it to previous measurements. If the pattern of changes in your HCG level is abnormal, it could indicate a problem. Your health care provider might check to see if you’re anemic — which could happen if you’ve experienced significant bleeding — and may also check your blood type.

Tissue tests. If you have passed tissue, it can be sent to a lab to confirm that a miscarriage has occurred — and that your symptoms aren’t related to another cause.
Chromosomal tests. If you’ve had two or more previous miscarriages, your health care provider may order blood tests for both you and your partner to determine if your chromosomes are a factor.