What Is a Fetal Anatomy Scan? A Complete Guide for Parents
You've felt the first flutters. Maybe you've already picked a name you're not telling anyone yet. And now there's an appointment on the calendar that everyone keeps calling the “big one” — the 20-week scan.
It is completely normal to feel excited and a little nervous. The scan is detailed because it is designed to look carefully at your baby's developing structures at a stage when there is still time to plan, arrange specialist care, or simply prepare.
This isn't just a quick look at the baby. It is a systematic examination covering roughly 40–50 individual checkpoints, and it usually takes around 30–60 minutes. Knowing what is actually being checked can make the appointment feel much less uncertain.
What Is a Fetal Anatomy Scan?
The fetal anatomy scan, also called the anomaly scan, mid-pregnancy scan or Level II ultrasound, is a detailed structural ultrasound performed between 18 and 24 weeks of pregnancy, most commonly around 20 weeks.
Unlike an early dating scan, which mainly confirms gestational age and checks the heartbeat, this scan examines how the baby's organs and body structures are developing.
At around 20 weeks, the baby is large enough for many structures to be assessed clearly while there is still enough amniotic fluid and room for movement to obtain views from different angles.
What Does the Fetal Anatomy Scan Check?
- Brain, skull and spine: skull shape and size, key brain structures, brain ventricles and the spine are assessed for structural concerns.
- Face: the eye sockets, nasal bone, lips and facial profile are examined.
- Heart: the four chambers, heart rate and rhythm, valves and major blood vessels are assessed. The heart is one of the most detailed parts of the examination and may sometimes require a dedicated follow-up scan.
- Chest and lungs: lung size and symmetry and the diaphragm are assessed.
- Abdomen and internal organs: the stomach, kidneys, bladder and abdominal wall are checked.
- Limbs and skeleton: all four limbs are assessed, including hands and feet, and bone measurements contribute to growth assessment.
- Placenta, umbilical cord and amniotic fluid: placental position, cord vessels and insertion, and fluid volume are evaluated.
- Growth measurements: head circumference, abdominal circumference, femur length and biparietal diameter are measured and compared with gestational-age norms.
What Are Sonographers Looking For?
Not every finding mentioned on an ultrasound report means that something is wrong. Small variations, sometimes called soft markers, may be noted because they form part of the overall assessment. Some resolve on their own or have little significance when seen in isolation.
An ultrasound report should therefore be discussed with your obstetrician or fetal medicine specialist rather than interpreted without context. A report saying that no gross structural abnormality was identified generally means that the structures examined appeared normal.
Why Might I Be Asked to Repeat the Scan?
A repeat scan does not automatically mean that something is wrong. Sometimes a clear view simply wasn't possible during the first examination.
- The baby was in a position that made a particular structure difficult to see, especially the heart.
- Maternal body type or an anterior placenta made certain views more difficult.
- A measurement needs to be checked again for confirmation.
How Should You Prepare for the Anatomy Scan?
- Follow your hospital's instructions about hydration. A full bladder may be useful for some earlier pregnancy scans, but it is less important around 20 weeks.
- You generally do not need to fast for an anatomy scan.
- Wear clothing that allows easy access to your abdomen.
- If permitted, bring your partner or a support person.
- Allow extra time for registration, the scan and the consultation afterwards.
- Write down questions you want to ask so you don't forget them.
When Might a More Detailed Scan Be Needed?
- Twins or multiple pregnancy.
- A previous pregnancy affected by a congenital condition.
- Maternal conditions such as diabetes or hypertension that may warrant additional fetal assessment.
- An abnormal first-trimester screening result.
- In selected situations, a fetal echocardiogram or other targeted imaging may be recommended.
What Does a Normal Anatomy Scan Mean?
A normal anatomy scan is reassuring, but no ultrasound can guarantee that a baby will have no health problems after birth. The scan provides a detailed assessment of structures that can be visualised at that stage.
If a finding needs further assessment, your doctor can explain what it means and whether another scan, specialist consultation or additional testing is appropriate.
The 20-Week Scan Is About Information, Not Just Reassurance.
It is tempting to think of the anatomy scan as simply the appointment where you get a good look at your baby. Its real value is the information it provides at a point in pregnancy when there is still time to plan for whatever the scan shows.
Take the photo, ask the questions and give yourself space to feel whatever comes up. The purpose is not perfection or guarantees. It is a clearer picture of your baby's development and the opportunity to make informed decisions.
Expert Fetal Medicine Care at Ankura Hospital
At Ankura Hospital for Women & Children, fetal assessment is approached with careful imaging, clinical interpretation and personalised counselling. If an anatomy scan raises a question, the next step is explained clearly so parents understand what the finding means and what, if anything, needs to happen next.