Midtrimester Ultrasound

Most pregnant women will be offered a routine midtrimester ultrasound examination. It can be performed from 19 weeks onwards but is preferably done between 20 and 22 weeks because we can more reliably see all required anatomy at that gestation. If we perform the ultrasound before 20 weeks it increases the chance that not all anatomy can be assessed and that a repeat examination may be required. The ultrasound is performed transabdominally. A full bladder is not required.


  • To confirm that the fetus is alive.

  • To diagnose multiple pregnancy if no earlier scan was performed

  • To confirm your due date if no earlier scan was performed

  • To assess fetal growth by measuring the fetal head, abdomen and femur

  • To assess the fetal anatomy. This involves a detailed examination of the fetal head, brain, face, lips, heart, stomach, lungs, abdominal wall, kidneys, bladder, spine, arms, legs, hands, and feet. Upon request, the fetal gender can be disclosed in most situations.

  • To assess the position of the placenta. In approximately 3%of pregnancies the placenta is low-lying at the midtrimester ultrasound. A repeat ultrasound is then recommended around 32 weeks. In the majority of patients, the placenta will no longer be low-lying then.

  • To assess the liquor volume.

  • To assess the length of the cervix.

  • To check for ovarian cysts or fibroids.

This examination is expected to detect the majority of major fetal malformations. It is important to appreciate however that even with the best ultrasound equipment not all abnormalities can be seen.

Sometimes abnormalities can be missed because suboptimal views are obtained. This can be due to difficult fetal position or the patient's weight. In these situations a repeat ultrasound is often organised a few weeks later when the fetus is bigger and/or in a different, hopefully better position.

Other times abnormalities may be missed despite good views. This may happen with conditions where the abnormality only becomes evident in later pregnancy or where there are in fact no structural changes in the fetus.

Photographs and Videos

The ultrasound examination will be recorded on USB free of charge. We will also send a picture of your baby to your phone by mms.


We welcome children at our practice. There are toys provided in the waiting area. Small children however are rarely able to relate to the images on the screen and may become restless, decreasing your and your partner's enjoyment of the ultrasound experience.

3D and 4D Ultrasound

Although 3D and 4D ultrasound can create some absolutely fantastic images of the unborn baby, it is very much dependent on the gestation and the position of the baby. We usually check the fetus in 2D first, to make sure that all is well. At the end of the examination, we do a 3D or 4D ultrasound. It is best to attend a 3D or 4D ultrasound with an open mind, realising that not everyone gets a 'as we've seen it on TV' image. We get beautiful images of the face if the baby is facing up and there is sufficient fluid around baby's face, but that is unfortunately not so every time. We will always try to get the best images in every situation but keeping the limitations of 3 and 4D ultrasound in mind avoids disappointment.