When Should Fetal Echo Be Present in a Vaginal Ultrasound?

First Heartbeats

• According to the American Pregnancy Association, a transvaginal ultrasound will be able to detect a heartbeat when a woman is five to six weeks pregnant. This date is calculated from the start of the last menstrual period; at this stage, the fetus is three to four weeks old. At this time, the baby should measure 2 to 4 mm in crown to rump length (CRL). The heartbeat at this stage is detected as a flutter.

  At six to seven weeks gestational age, or four to five weeks fetal age, the heart will begin to beat with a steadier rhythm that can be counted and measured. A normal heartbeat for a fetus at six to seven weeks is 90 to 110 beats per minute. At 5 mm CRL, the heartbeat will definitely be visible on a vaginal ultrasound. If the embryo measures less than 5 mm CRL, the heartbeat will not be visible. At this point the doctor will advise whether the pregnancy is viable or not.

Heart Structure

• The American Heart Association recommends that women who have certain risk factors should have a fetal echocardiogram performed. This is performed in a similar fashion to a vaginal ultrasound but focuses on the heart of the baby. Women who have a history of congenital heart disease in their family, or who have had fetal heart abnormalities detected through a routine scan, such as an abnormal rhythm, should have a fetal echocardiogram performed.

  This procedure can be performed through vaginal scanning as early as 14 weeks. At this time, the structure of the heart, including the chambers and valves, will be visible. A fetal echocardiogram can diagnose many serious fetal heart problems, such as a cardiac malformation. This allows doctors to plan for the delivery and plan how to treat the baby after birth. A fetal echocardiogram affords the best option for pre-birth planning and allows both doctors and parents to prepare for most serious heart issues that may arise after birth.