In early pregnancy, an ultrasound is done to confirm if the pregnancy is viable or date the pregnancy if the mother is unsure about her last menstrual cycle. Later on, it is done periodically to determine fetal health and expected date of delivery.
Two types of early ultrasounds may be performed: abdominal ultrasonography and trans-vaginal ultrasonography.
Read more: 3D/4D Ultrasound During Pregnancy
In an abdominal USG:
- A small gestational sac or yolk sac is seen in the 5th week of pregnancy.
- A fetal pole, the first sign of a viable pregnancy is seen in the late 5th or early 6th
- In the mid-6th to 7th week, a fetal heartbeat can be seen, though the Doppler does not detect the sound until much later.
In a trans-vaginal USG:
- A gestational sac is usually seen in the 3rd to 4th
- A fetal pole is seen in the 5th to 6th
6th to 7th week is considered the best time for an early ultrasound as a fetus with a heartbeat is visible.
Read more: Early Signs of Pregnancy