What is Detailed Screening Scan?

Detailed Screening Scan is a major ultrasound scan performed at 20 – 22 weeks to check the physical structures of the fetus and measure the growth parameters. It also observes the position of the placenta and the amniotic fluid.

The fetal brain, nose, lips, heart, stomach, kidneys, limbs and bowel will be assessed to detect for anomaly. The gender can also be known.

Prenatal Tests: Who should do this scan?

Most babies are normal and healthy. However, 2-3% women may deliver a baby with a birth anomaly. It is recommended that this detailed scan is offered to all expectant women.

How is the scan performed?

The scan is performed by a specialist sonographer who is trained in the use of ultrasound. You will be asked to lie down and a gel will be applied on your belly. The sonographer will move a hand-held probe gently over your belly, to obtain images of your baby on the scan monitor.

The scan takes about 30 minutes and you will not experience any pain or discomfort during the scan.

There may be times when the fetal structures are not well visualised due to the fetal position. You may need to wait for the baby to change to a different position before obtaining an optimal view of the specific structure. This may prolong the time required for the best interest of your baby.

Will the ultrasound harm me and my baby?

No. Ultrasound scan is a safe procedure. There is no radiation used. Research has proven that there are no harmful effects.

How will I find out the result of the scan?

A detailed scan report will be sent to your doctor who will review the results and discuss with you.

Can this prenatal scan detect all abnormalities?

It is important to know that while many major structural abnormalities are picked up by this scan, some are not. Accuracy is 70-80% in best hands.

Although the scan is normal, there is a likelihood that the fetus may not develop normally.

Does an ultrasound marker mean that my baby is abnormal?

  • Ultrasound markers are slight deviations from the normal anatomy seen on an ultrasound. Some examples of markers are increased brightness in the fetal bowel, thickened neck nuchal fold and short leg length.
  • Markers may be seen in healthy babies although they are more commonly seen in babies with chromosomal abnormalities such as Down Syndrome and further tests may be required.
  • Most babies found to have markers subsequently turn out to be healthy.

What if there is an abnormality detected on the prenatal scan?

If abnormalities are suspected, you may need to have further tests. Your doctor will discuss the options with you.