GUIDE
The anatomy scan is a detailed ultrasound between weeks 18 and 22 that checks your baby's major organs, growth, and development.
This is the most comprehensive ultrasound of your pregnancy. The sonographer will systematically examine the brain, heart, spine, kidneys, limbs, and more. It typically takes 30 to 60 minutes and is one of the most anticipated appointments of pregnancy.
Be prepared from day one
The anatomy scan — also called the mid-pregnancy ultrasound, level 2 ultrasound, or 20-week scan — is the most detailed ultrasound examination you will have during a typical pregnancy. It is performed between weeks 18 and 22 (most commonly at week 20) and uses standard 2D ultrasound technology.
Unlike the dating ultrasound you had in the first trimester, which mainly confirmed gestational age and heartbeat, the anatomy scan is a systematic head-to-toe examination of your baby's developing organs. It is a standard part of the prenatal care schedule and is recommended by ACOG for all pregnancies.
The scan is performed by a trained sonographer. A radiologist or maternal-fetal medicine specialist will review the images and send a report to your provider. You will typically discuss results at your next prenatal appointment, though some practices review findings immediately.
| Structure | What They Look For |
|---|---|
| Brain | Cerebral hemispheres, ventricles, cerebellum, cavum septum pellucidum — checking for normal structure and development |
| Heart | Four chambers, valves, major vessels, heart rate — the most complex part of the scan. Some heart defects can be detected here |
| Spine | All vertebrae checked for alignment and closure — screening for spina bifida and other neural tube defects |
| Kidneys | Both kidneys present and normal size. Mild dilation (pyelectasis) is a common finding that usually resolves |
| Stomach | Visible and fluid-filled, confirming the baby is swallowing amniotic fluid normally |
| Bladder | Visible and filling/emptying, confirming normal kidney function |
| Limbs | Arms, legs, hands, and feet — checking for normal length and bone structure |
| Face | Lips checked for cleft lip (cleft palate is harder to detect). Nasal bone, eye orbits assessed |
| Placenta | Location (checking for placenta previa), appearance, and cord insertion point |
| Amniotic fluid | Measured to ensure adequate volume — too much or too little may indicate an issue |
| Umbilical cord | Three vessels confirmed (two arteries, one vein) and insertion site checked |
| Cervix length | May be measured to assess preterm birth risk, especially if you have risk factors |
The fetal heart is the most complex structure examined during the anatomy scan. The sonographer checks the four chambers, the valves, the outflow tracts (aorta and pulmonary artery), and the heart rate. Congenital heart defects are the most common type of birth defect, affecting about 1 in 100 babies.
The anatomy scan detects about 30 to 50 percent of major heart defects. This is not because sonographers miss things — some defects are simply difficult to visualize on standard ultrasound. If anything looks unusual, your provider may recommend a fetal echocardiogram, which is a specialized heart-focused ultrasound performed by a pediatric cardiologist.
If you had an elevated risk on your NIPT or nuchal translucency scan, your provider may request a more detailed cardiac evaluation as part of this scan.
The anatomy scan is one of the most exciting prenatal appointments. But remember — its primary purpose is medical, not just to get photos.
Most anatomy scans come back completely normal. But when a finding is identified, it is important to understand what that means.
Findings fall into a spectrum. Some are "soft markers" — minor variations like a mildly dilated kidney (pyelectasis) or an echogenic intracardiac focus (a bright spot on the heart). These are common, usually harmless, and most resolve on their own. In the past, some soft markers were associated with chromosomal conditions, but if you already had normal NIPT results, isolated soft markers are generally not concerning.
Other findings are structural and may require follow-up. This could mean a repeat ultrasound in a few weeks to monitor growth, a referral to a maternal-fetal medicine specialist, or in some cases, a recommendation for amniocentesis to check for a genetic cause.
If something is flagged, try not to panic before getting the full picture. Many findings turn out to be normal variants, and even true structural differences often have excellent treatment options.
If you want to know your baby's sex, tell the sonographer at the start. If you do not want to know, say that too — some sonographers will point things out by default. NIPT can also reveal sex as early as week 10 if you cannot wait for the anatomy scan. See our NIPT guide for details.
Sometimes the baby's position makes it impossible to get all the required images in one session. The baby might be facing your back, curled tightly, or simply not cooperating. This is not a cause for concern — it just means you will need to come back for a follow-up scan to complete the remaining images.
Your sonographer may ask you to walk around, drink cold water, or shift positions to encourage the baby to move. If the key images still cannot be captured, a follow-up is typically scheduled within one to two weeks.
For a complete view of all the prenatal testing throughout your pregnancy, see our prenatal visit schedule and pregnancy blood tests guide.
This guide is for informational purposes only and is not a substitute for professional medical advice. Always consult your healthcare provider with any questions about your pregnancy.
