20 Week Scan / Detailed Anomaly Scan

“The 20 week scan”
(Preferably 20–24 weeks €175.00)
(Twins add €60)

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Detailed anamoly scans
Price: €175.00

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 examine changes in the normal anatomy that may indicate an abnormality.

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 the 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 the baby’s true 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.


The anomaly scan is the best and most detailed scan we have available for the assessment of foetal development. However, not all abnormalities can be detected. There are many things that can affect how well we see the structures of the baby. These can include the position and age of the baby, the amount of fluid around the baby, the type of body tissue you have, your own body weight and if there is scar tissue from previous abdominal surgery such as a Caesarean. In addition to this, some foetal abnormalities are not visible at the time of the scan or they don’t develop until much later (>24 weeks). Problems such as cerebral palsy or learning disabilities like autism are not detected as they are not associated with visible structural differences. In a small number of cases, babies are born with abnormalities, even though no problem was identified by the scan.

It must be understood that ultrasound does not have 100% diagnostic accuracy. There is no diagnostic test in medical practice however diligently performed which is free from false-negative findings. It must be emphasized that although many malformations can be identified during the systematic evaluation of the fetus during the second-trimester anomalies survey, it is well-established that some anomalies may be missed even with the best ultrasound equipment in the hands of highly experienced and well-trained professionals. 1

1. Salomon LJ, Alfirevic Z, Berghella V, Bilardo C, Hernandez-Andrade E, Johnsen SL, et al. Practice guidelines for performance of the routine mid-trimester fetal ultrasound scan. Ultrasound Obstet Gynecol. 2011;37:116–26.

Anomaly Scan Procedure

At Ultrasound Dimensions, our anomaly scan procedure Includes:

  • Ultrasound exam
  • Medical obstetric ultrasound report
  • Glossy picture print

Please note for twins there is an additional fee of €50.00

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Take a detailed look at how we perform the 20 Week Pregnancy Scan:

20 Week Scan / Detailed Anomaly Scan FAQs

Do I need to book an appointment?

Yes, ultrasound exams do need an appointment.
If you cannot attend your appointment we appreciate it if you can give us 24 hours notice.

What stage do I have an anomaly pregnancy scan?

We perform the Anomaly pregnancy scan from 20 weeks up to 24 weeks of pregnancy.

How should I prepare for an anomaly pregnancy ultrasound?

When you attend for an anomaly pregnancy ultrasound you do not need a filled urinary bladder to help view the pregnancy. You will need to know your established due date. It is important to wear loose comfortable clothing.

Why is an anomaly scan performed?

The anomaly scan essentially examines the baby’s anatomy in a detailed manner and is carried out between 20 and 24 gestational weeks. Measurements & all your baby’s organs will be checked by the Sonographer while capturing images as well. They will check your baby's spine, face, the baby's abdominal wall, stomach, kidneys, and heart. Your baby’s hands, arms, legs, and feet will also be checked. The Sonographer will also take measurements of your baby’s abdominal circumference, femur, and head circumference. The Sonographer will also check the umbilical cord, amniotic fluid around the baby & the placenta.

Will I be able to see the scan?

Yes, the ultrasound is available for you to view on a large screen located at the end of the ultrasound couch. The sonographer will explain what you are looking at and point out various items to look at on the ultrasound. You will also be able to hear the baby’s heartbeat. We aim to make this ultrasound scan an enjoyable experience for you.

What to expect at Ultrasound Dimensions?

When you arrive at Ultrasound Dimensions you will be met by our receptionist. You will then be asked to complete a waiver, even if you have been here before. You can then relax in our waiting area until the sonographer comes to meet you and take you to the scanning room. Your personal details from your completed waiver will be confirmed by the sonographer before beginning the scan.

What happens during the anomaly pregnancy ultrasound scan?

The anomaly scan also known as the twenty-week scan is a non-invasive, trans-abdominal scan (on the stomach area), and you don’t have to attend with a full bladder for this scan. An abdominal scan is performed by placing some gel and the transducer onto the abdomen of the patient.

Will I be able to find out the gender of my baby?

At 18 weeks or later we can determine the gender of your baby. However, sometimes, the baby is not in a desirable position to tell the gender. If you want to determine the gender of your baby, please let us know on your registration form and confirm with the sonographer at the start of your scan. Determining the gender of your baby depends on baby to be in a position that can allow the Sonographer to view the genital area and sometimes the baby may not oblige!

What happens if a problem is suggested?

During your scan, if a problem is suggested, you will be notified by the sonographer that there may be a concern and advised to contact your obstetrician to discuss our findings in more detail. We will provide details of our findings for you and you are welcome to contact us for further clarification at any stage.

Do I need a doctor's referral for a pregnancy ultrasound?

Pregnancy scans at our centre are elective so you don't have to have a referral. Just call or email to make an appointment.

Can family members attend my ultrasound appointment?

A pregnancy scan is a family affair at our clinic, so you can share your baby scan experience by bringing whomever you want and as many people as you like.