What are the chances that a miscarriage was not found at 12-week checkup?

It is rare for a miscarriage to go unnoticed at a 12-week checkup, as the fetus is typically large enough to be easily visible on an ultrasound. However, there are a few cases where a miscarriage may not be detected:

- Vanishing twin syndrome: This occurs when one of two or more fetuses in a multiple pregnancy dies and is absorbed by the other fetus or the mother. This can happen without any noticeable symptoms or signs.

- Missed miscarriage: This occurs when the fetus dies, but the body does not expel the pregnancy tissue. The pregnancy test will continue to be positive, and the woman may not experience any symptoms of miscarriage.

- Ultrasound error: In rare cases, an ultrasound may not be able to detect a miscarriage. This can happen if the ultrasound is performed too early in the pregnancy, if the fetus is located in an unusual position, or if the woman is obese.

If you have experienced any signs or symptoms of miscarriage, such as vaginal bleeding, abdominal pain, or a sudden decrease in pregnancy symptoms, it is important to see your doctor even if you have had a 12-week checkup.