Dating ultrasound what to expect

That initial glimpse at your baby-to-be is unforgettable. Getting that initial glimpse of your baby on an ultrasound machine is one of the most exciting moments of pregnancy. Yet many parents-to-be are filled with questions about the first pregnancy ultrasound: When should I get the exam? Will it hurt? What are doctors looking for? We spoke with experts to break down your most pressing questions.

An ultrasound is a highly accurate means of dating a pregnancy. In a normal pregnancy, ultrasound can provide an estimate of the gestational age to within five to seven days of accuracy. In the first trimester, doctors usually use a transvaginal rather than abdominal ultrasound. The transvaginal ultrasound provides the most accurate information, given that the early developing gestational sac and fetal pole are extremely tiny at this point. A transvaginal ultrasound can get closer to the developing pregnancy. In a transvaginal ultrasound, the doctor or technician inserts a thin probe into the vagina.

A dating scan is an ultrasound examination which is performed in order to establish the gestational age of the pregnancy. Most dating scans are done with a trans-abdominal transducer and a fullish bladder. If the pregnancy is very early the gestation sac and fetus will not be big enough to see, so the transvaginal approach will give better pictures. Dating scans are usually recommended if there is doubt about the validity of the last menstrual period. By 6 to 7 weeks gestation the fetus is clearly seen on trans-vaginal ultrasound and the heart beat can be seen at this early stage 90 to beats per minute under 6 to 7 weeks, then to beats per minute as the baby matures.

Petrina is an enthusiastic and caring Sonographer with 20 years experience in obstetrics and gynaecological ultrasound. With her love of obstetric scanning and patient contact she lectures and tutors future Sonographers at the Australian Institute of Healthcare Education. Petrina is also a wife and busy mum to two boys, where together as a family, they love spending time outdoors. That first appointment with the sonographer can be a little daunting, but it's an important time to gather some key information about your growing baby. Congratulations, you have found out you are pregnant, and the first scan in your pregnancy should be an exciting time.