Northern Ultrasound for Women

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Northern Ultrasound for Women, Suite 8 Level 2, 8 Martin St,
Heidelberg 3084
Tel 03 9457 1466
Fax 03 9457 1400

Obstetrical Ultrasound

Early Pregnancy Scans (6 to 10 weeks)

Also called the Dating Ultrasound Scan, the purpose of this scan is basically to determine the pregnancy life (confirmation of the baby's heartbeat), number and dating of the pregnancy. At this early stage which is the embryonic phase mainly only very primitive anatomy is appreciated and a transvaginal scan approach is usually necessary. This scan reassures couples that are concerned about miscarriage risk that the pregnancy is alive and the gestational age can be verified.

First Trimester Scans (also called a “nuchal scan” or “NT scan”) (11 to 14 weeks)

This scan is done via the transabdominal approach however a transvaginal scan is often necessary to obtain more detail of the early fetal anatomy. Pregnancy dating and the number of babies are also identified at this time. The main purpose of this scan is to obtain ultrasound data for the first trimester combined screen which includes the fetal body length and the neck skin thickness.

The most sensitive screening test for Down syndrome is the combined screen which uses the above ultrasound data as well as maternal age and blood levels of specific hormones to assess this individual risk of chromosomal abnormality. The risks are assessed as either low or high.This is a screening test only and if high risk will detect 80-90% of Down sydrome pregnancies.

It is recommended that you have your first trimester screening performed at an accredited practice. This ensures the practice undergoes regular audits of its performance with RANZCOG (Royal Australian and New Zealand College of Obstetricians and Gynaecologists). Northern Ultrasound is an accredited practice for first trimester screening.

Mid Trimester Scans (19 to 22 weeks)

This is referred to as the routine anomaly scan because a screen of the fetal anatomy is performed. This scan is the most time consuming of routine pregnancy scans and is performed via the transabdominal approach with recourse to transvaginal scanning if necessary. The fetal measurements are performed and early growth can be assessed. At this stage there is the opportunity for the parents to appreciate some features such as the facial profile, fingers and toes.

Third Trimester Scans (24 weeks onwards)

These scans are performed as directed by the obstetrician in cases where fetal growth, a specific anatomical region or the placental site needs review. The fetal weight is estimated from standard fetal measurements. Assessment includes liquor volume and the parameters of wellbeing such as the cord blood flow pattern.