Can i be sure an ultrasound will detect my baby's heartbeat?

Yes: Although it depends on the gestational age and the type of ultrasound (abdominal v vaginal), an ultrasound should be able to identify a heartbeat early in the pregnancy. If the fetal length is greater than 5mm, a heartbeat should be identifiable on transvaginal sonography. If the fetus is too small to identify the heartbeat, a repeat sonogram should be scheduled in 1-2 weeks.

If it's there: If the fetus is at least 7 weeks gestational age then the fetal heartbeat should be visible if the fetus is alive. If the patient is obese, a transvaginal scan may be required to obtain sufficient detail.