<P> A gestational sac can be reliably seen on transvaginal ultrasound by 5 weeks ' gestational age ( approximately 3 weeks after ovulation ). The embryo should be seen by the time the gestational sac measures 20 mm , about five - and - a-half weeks . The heartbeat is usually seen on transvaginal ultrasound by the time the embryo measures 5 mm , but may not be visible until the embryo reaches 7 mm , around 7 weeks ' gestational age . Coincidentally , most miscarriages also happen by 7 weeks ' gestation . The rate of miscarriage , especially threatened miscarriage , drops significantly if normal heartbeat is detected . </P>
<P> A gestational sac can be reliably seen on transvaginal ultrasound by 5 weeks ' gestational age ( approximately 3 weeks after ovulation ). The embryo should be seen by the time the gestational sac measures 20 mm , about five - and - a-half weeks . The heartbeat is usually seen on transvaginal ultrasound by the time the embryo measures 5 mm , but may not be visible until the embryo reaches 7 mm , around 7 weeks ' gestational age . Coincidentally , most miscarriages also happen by 7 weeks ' gestation . The rate of miscarriage , especially threatened miscarriage , drops significantly if normal heartbeat is detected . </P>
when is the first us done in pregnancy
when is the first us done in pregnancy
5 weeks ' gestational age
5 weeks ' gestational age