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Obstetrics/ Calculator

What preparation is required?

You will need to finish drinking 1 litre of water 1 hour prior to your appointment time, so that you arrive with a full bladder.  Try not to empty your bladder. If your bladder is not sufficiently full, this may delay the scan or cause the scan to be rebooked.

By having a full bladder it will help in visualizing the baby.

Please click here to use our pregnancy calculator

Please note - Medicare will only cover 12 & 20 week ultrasounds.  If an additional scan is required to determine the sex of the baby, this may not be rebated under Medicare.

Dating Ultrasound

The purpose of the dating examination is to assess:

• Position of pregnancy (inside the uterus)
• Number of babies
• Presence of heart motion
• Age of pregnancy (from the first day of the menstrual period)
• The ultrasound appearance will depend on the age of the pregnancy. At 5 weeks gestation only a gestational sac will be seen. After this a yolk sac will be visible, then a small fetus.
• Dating the pregnancy by measuring from the head to the bottom (crown-rump length) is very accurate (+/- 3 days).
• A CD with images will be provided for you at the end of the examination.

 Nuchal Translucency

• A Nuchal Translucency ultrasound scan is performed at approximately 12 weeks gestation. Ultrasound measures the fluid that normally accumulates under the skin behind the baby’s head and neck. Too much fluid in this space has been associated with chromosome abnormalities such as Down Syndrome. The scan is usually transabdominal, but around 1 in 10 women will require a vaginal scan to obtain the clearest image.

What is the Blood Test?  

Along with the ultrasound a blood test should be done as part of the assessment. The blood test is usually done on the day of your scan, after the ultrasound. The blood test measures two chemicals that are produced by the placenta. These chemical are called free-βhCG and PAPP-A. 

A combination of your age, the size of the baby, the thickness of the Nuchal translucency measurement and the levels of the blood chemical allow us to calculate a numerical risk assessment for Down Syndrome for the pregnancy.

A CD with images will be provided for you at the end of the examination.

2nd Trimester Ultrasound - 20 weeks

At this time in the pregnancy (20 weeks), good detail can usually be obtained at this time, allowing a more complete physical assessment.

The purpose of this examination is to assess:

• The number of babies in the uterus
• The age of the baby
• The baby’s physical development
• The position of the placenta
• The amount of amniotic fluid around the baby]
• The appearance of the cervix

Many patients find this to be exciting and that it helps with bonding, however it remains primarily a medical examination.

A CD with images will be provided for you at the end of the examination.

Patients are not permitted to take photos or do any filming during the examination.

Can I bring the family?  Yes, we welcome family members of the immediate family or a support person. However, young children may need to be supervised away from the examination room by a family member. We will ask that you turn off your mobile phone.

 3rd trimester Ultrasound

Your Doctor may request a third trimester scan to be done. This is to assess

• Position of the baby
• Size of the baby
• Amount of fluid surrounding the baby
• Placental resistance to flow
• Baby’s current state of health
• Position of the placenta in relation to the cervix

Most babies are head down towards the end of the pregnancy. Occasionally the baby can be in a breech position, where the bottom is closet to the cervix (opening to the uterus).

The age of the baby is established in early pregnancy. The size of the baby can be compared with the size expected for this stage of pregnancy, giving information about the baby’s growth. An estimate of the weight can be calculated from the measurements.

Please click here to use our pregnancy calculator