20 Week Scan / Detailed Anomaly Scan
“The 20 week scan”
(Preferably 20–24 weeks €165.00)
The 20 Week Scan or anomaly scan as it is sometimes called is ideal for those parents looking for reassurance or as a secondary option when an earlier screening test has not been performed. Furthermore, it provides an added opportunity to assess the baby’s well being and encourage further bonding.
Detailed Anomaly Scan Checks
Your baby’s internal organs are examined in cross-section which may be difficult for you to make out. Bones appear white, fluid is black and soft tissues may seem to be varying degrees of grey. At this time we will check for soft markers which are changes in the normal anatomy and may indicate an abnormality. They are common and can frequently be seen on a 20 week scan. The four most common markers are choroid plexus cysts, renal pelvic dilatation, echogenic bowel and an echogenic foci attached to the muscle of the heart. It is important to understand that although these can be seen in affected pregnancies they can also be seen in normal healthy babies and the vast majority will not cause any problem at all. If you had screening earlier in your pregnancy e.g. NT then the presence of any soft markers later in pregnancy are even less likely to be of any significance.
The baby’s head is examined for shape and size. Internal structures such as the ventricles of the brain and cerebellum are examined. The sonographer will do standard measurements and look at the baby’s lips and nose for any obvious defects.
The spine is assessed in both long and short axis views to make sure that all of the vertebrae are in alignment and that the skin is closed. The baby’s abdominal wall is checked at this time too to make sure that all abdominal organs are in their correct position. 90% of all abdominal wall and spine defects can be picked up by ultrasound.
The chest is assessed to view the lungs and the position of the heart. At Ultrasound Dimensions we are concerned with raising the standard of detecting a baby with a possible heart defect. The first step in improving care of “heart babies” is improving the detection of heart disease before birth. The “5 Transverse Views” is a practical and proven way to screen for heart disease at the routine “20 week” scan set up by the Tiny Ticker organization, a national charity in the UK.
The kidneys, stomach, and bladder are also imaged. The baby swallows some of the amniotic fluid that it lies in and so some of that fluid will be seen as a black bubble in the stomach and the urinary bladder as well. Yes, the baby has a wee inside about every half hour so the urinary bladder fills and empties during the scan.
Baby’s legs, arms, hands, and feet are examined. The umbilical cord is assessed to count the number of vessels.
The placenta will be documented to lie at the fundus or anteriorly or posteriorly and to ensure that the placenta does not cover the cervix (the opening of the womb).
There should be enough amniotic fluid at this stage to allow baby to move around freely.
The routine measurements that are taken include Biparietal diameter of the head (BPD), head circumference (HC), abdominal circumference (AC) and femur length (FL). These measurements will have an accuracy of approximately one to two weeks plus or minus baby’s gestational age. We consider your baby’s measurements normal if they fall within that range. Not all babies in the womb are exactly the same size because parents aren’t the same size and babies are unique to their parents.
Anomaly Scan Procedure
At Ultrasound Dimensions, our anomaly scan procedure Includes:
- Ultrasound exam
- Medical obstetric ultrasound report
- Glossy picture print