What does the detailed anatomy scan show?

For many parents-to-be, the detailed ultrasound in the middle of pregnancy is the first chance to see their baby in this much detail. Also called the second-level or anomaly scan, it is an important screening exam that looks at the baby's organs and growth.

When is it done?

The detailed ultrasound is usually done between weeks 18 and 22; Türkiye's Ministry of Health antenatal care guideline also recommends the fetal anomaly scan in this window. The scan usually takes about half an hour. If the baby is moving a lot or isn't in a good position, it can take longer; you may be asked to take a short walk and come back, or be given a new appointment soon after. If you've reached these weeks and no detailed scan has been planned yet, ask your doctor. This applies in Türkiye; if you live elsewhere, follow your doctor's advice and your own country's health program.

The scan is usually done over your belly: you lie down in a dimly lit room, a cold gel is put on your belly and the doctor moves a handheld probe over it; this can be a little uncomfortable. If you have risk factors or a problem is suspected, more detailed or repeated scans using special techniques such as Doppler may be planned.

What is checked?

The doctor performing the ultrasound examines the baby's body systematically and measures their growth:

• Brain, spine and face (including the lip and palate)
• Heart
• Abdominal wall, stomach and kidneys
• Arms, legs and bones
• The baby's growth and estimated weight, based on measurements
• The position of the placenta, the amount of amniotic fluid and blood flow in the uterus

The scan looks for signs of conditions such as open spina bifida, cleft lip and palate, serious heart problems, openings in the abdominal wall, kidneys that haven't developed and severe skeletal conditions. Because the doctor is focusing on the details, they may be quiet for a while during the scan, and sometimes they may ask a colleague to look at the images too.

If the baby is in a good position, their sex may also be visible, and you may be asked whether you'd like to know. But that isn't the main purpose of the scan. Results are usually explained once the scan is finished, and most parents-to-be are told that no signs of a condition were seen.

Does the ultrasound show everything?

No. A detailed ultrasound can pick up many structural differences, but some conditions are easier to see than others, and some may not be visible at all. So a normal result doesn't rule everything out. This is a screening exam: if something is found, your doctor may suggest more ultrasounds, a specialist assessment or diagnostic tests such as amniocentesis. You decide whether to have these tests once you've been fully informed.

Ultrasound uses sound waves, and so far there is no evidence that it harms the baby. Even so, it's recommended that ultrasound be used only for medical reasons and only by trained professionals. A normal scan doesn't replace seeing your doctor if you later have a problem such as bleeding, leaking fluid or fewer baby movements.

“This scan isn't a test you can fail; it's a chance to get to know your baby better, so don't hesitate to ask questions.”

Preparing for the appointment

• Arrive a little early; wear comfortable clothes that make it easy to uncover your belly, and take out a belly piercing if you have one.
• Bring your previous ultrasound and test results.
• If you'd like pictures of your baby, ask in advance whether that's possible.
• Ask in advance whether your bladder should be full or empty.
• If you'd like to bring someone with you, check the hospital's policy.
• Write down your questions: Could all the structures be seen? Is a follow-up needed? Is the placenta in a good position?