Pregnancy Imaging

  • Overview
  • Pre Examination
  • The Examination
  • Post Examination

Why have an Ultrasound Scan?

The most common reasons to have an ultrasound in pregnancy are to determine the age of the baby, to confirm its wellbeing and to make sure the baby is growing normally. After 12 weeks gestation, the age is confirmed from calculations using the head, abdomen and upper leg measurements. The ultrasound scan can also identify fetal abnormalities as well as twins.

What is nuchal translucency measurement?

This prenatal screening test uses ultrasound to measure the clear (‘translucent’) space in the tissue at the back of the baby’s neck. Babies with abnormalities often accumulate more fluid at the back of their neck in early pregnancy, causing a clear space on the ultrasound to be larger. The measurement is performed between 11 and 14 weeks of pregnancy and can help assess your baby’s risk for Down Syndrome and other chromosomal abnormalities. We send the translucency measurement to the laboratory where they combine the results of your blood test and calculate a risk factor for this pregnancy. The nuchal translucency screening test will not give you a definite diagnosis but it can help you decide whether you want to undergo further diagnostic testing. The ultrasound test is painless and involves no risk to your pregnancy.

What are the risks?

Diagnostic ultrasound has been used in pregnancy for 40 years with no known side effects or risks.

Will it hurt?

There is no pain involved in an ultrasound scan of your pelvis although there may be minor discomfort for some women in maintaining a full bladder required in early pregnancy scans.

What will I see?

The baby’s heartbeat, body and limb movements can usually be identified. The baby can be seen moving during an ultrasound examination earlier in the pregnancy than you are able to feel it move.

This appointment generally takes between 15-30 minutes

Before your Examination

If you are over 18 week’s gestation and have had a previous scan in this pregnancy you do not need any preparation. If you have not had a previous scan in this pregnancy and are at less than 12 weeks gestation you will need to empty your bladder 1 hour prior to the examination. Once empty, immediately drink 3 large glasses of water (approx 750mls) and hold on to this until the ultrasound examination.


Your Examination

Family members are welcome to join you during the ultrasound scan.  Please bear in mind that the ultrasound room will only accommodate a small number of people.

Factors that determine the length of the scan are:

  • The reason the scan is required
  • The age of the fetus
  • The number of fetuses
  • How much fluid is present around the baby
  • The position of the baby in the uterus
  • How full the bladder is
  • Whether an internal or trans-vaginal scan is required
  • The mother's body mass index


During your pregnancy two to three scans may be requested by your doctor or midwife. This may be to visualise an area not seen adequately on a previous scan, to check your baby’s growth or to see where the placenta is located before delivery of your baby. The scan will take approximately 10-30 minutes and is performed by a trained technician called a sonographer.

What does an internal or trans-vaginal scan involve?

To get a better view of the baby, a trans-vaginal scan may be necessary. This scan involves a transducer or probe similar in size and shape to a tampon that is inserted into your vagina and connected to the ultrasound machine. This gives us a better view of the fetus as the probe is closer to the uterus. Usually it is not uncomfortable.


When your ultrasound scan is complete, the radiologist will interpret the images and send a report to your doctor or midwife.

A copy of your scan images are available for you if you wish.  Please ask at reception.