The 18-22 Week Ultrasound

Even if you choose not to have prenatal screening, ultrasounds are an important part of your routine prenatal care. The Society of Obstetricians and Gynecologists of Canada recommends that all pregnant women in Canada be offered an 18-22 week ultrasound. At the 18-22 week scan, your baby has developed and grown to the size where we can more clearly examine the baby’s anatomy (for example the developing organs, hands and feet, face) and measure the baby’s growth. Most birth defects, if present, can be identified during this ultrasound. If you have not had any previous ultrasounds, the 18-22 week ultrasound will be also used to confirm your due date.

Will I require any more ultrasounds after the 18-22 week ultrasound?

Additional ultrasounds may be required at the request of your health care provider. Sometimes ultrasounds are recommended if there are questions about the baby’s position, the mother’s or the baby’s health, or the baby’s growth.

I was told there were ‘markers’ at my 18-22 week ultrasound, what does this mean?

A ‘marker’ is a slight difference in organ development that may be detected during an ultrasound. Examples of markers are:

  • Echogenic bowel(a brightness of the baby's intestine)
  • Echogenic foci (a bright spot in the baby’s heart)
  • Choroid Plexus Cyst or CPC (a bright spot in the baby’s brain)

Markers are often seen in normal babies but are also seen in babies with chromosome conditions such as Down syndrome or Trisomy 18. If a marker is found in your ultrasound, you will be provided with more information and may also receive a referral for prenatal genetic counselling or to a specialist in maternal fetal medicine.