Our midwife Melissa says:
The 20-week scan is a key ultrasound in a woman’s pregnancy. Of all the scans that are offered, this is the one that is almost universally accepted. The ultrasound is attended between 18 and 20 weeks of pregnancy. It is called a morphology scan or anomaly scan. The purpose of the ultrasound is to systematically view and measure all of the baby’s organs and structures to ensure that they have grown and developed normally. All of the baby’s internal organs are examined and measured, including the brain, heart, kidneys, stomach, bladder and so on. The bones are measured to ensure that they are the right size and shape.
As well as looking at the baby, the scan looks at a few other things. It also looks at the placenta to determine where it is located in relation to your cervix. The scan will check to see that there are three vessels on the cord. Your cervix may be measured for its length and to ensure that it is closed. The fluid around the baby will also be assessed to ensure that it is the correct volume.
As well as all of the above, the scan can detect twins, determine the sex of the baby and check the baby’s heartbeat. Because it is such a thorough and comprehensive scan, it can take some time: up to 45 minutes. Sometimes the baby’s position means that not all of the measurements and images can be obtained, so some women are asked to go for a walk or change their position to see if this shifts the baby’s position.
Many clinics will provide pictures and/or a DVD of the scan: you might like to ask about this when you make your appointment. Enjoy your scan!
This answer was written for Birth by midwife Melissa Maimann from Essential Birth Consulting.