Fetal anomaly scan

An anomaly scan is a thorough, structured ultrasound analysis of your baby carried out by a gynecologist specially trained in targeted prenatal ultrasound.

It shows whether your baby is developing normally and where the placenta is lying in your uterus. It is sometimes called your mid-pregnancy ultrasound scan and must take place when you are between 18 and 23 weeks pregnant. It is one of the most important pregnancy scans and helps us find out whether the baby has a disability or not. Unfortunately however the anomaly scan is not 100% accurate and couples need to consent that they understand this. 

What we look for particularly: 

  • The shape and structure of your baby's head and brain.
  • Your baby's face to check for a cleft lip.
  • Your baby's spine, both along its length and in cross section, to make sure that all the bones align and that the skin covers the spine at the back.
  • Your baby's abdominal wall, to make sure it covers all the internal organs at the front.
  • Your baby's heart and lungs. The top two chambers (atria) and the bottom two chambers (ventricles) should be equal in size. The valves should open and close with each heartbeat.
  • Your baby's stomach and bowels. Your baby swallows some of the amniotic fluid that he lies in, which is seen in his stomach as a black bubble.
  • That your baby has two kidneys, and that urine flows freely into his bladder.
  • Your baby's sex, arms, legs, hands and feet.

As well as this detailed look at how your baby is growing, we check the position of the placenta, the umbilical cord and that there's enough amniotic fluid. During the scan we will measure your baby's head, cerebellum, abdominal circumference and the length of all long bones.

Some conditions, including late-onset ossification defects and bowel obstructions, may not be seen until later in your pregnancy. However, having your anomaly scan will most likely rule out all these conditions, as the vast majority of babies are born healthy. 

Other problems may mean a baby needs surgery or treatment after birth, or even surgery while still in the uterus. There will be a whole range of people to support you if there is a difficulty.