Around the midpoint of pregnancy, most women are offered a detailed ultrasound known as the anatomy scan, mid-pregnancy ultrasound, or level 2 ultrasound. Typically performed between 18 and 22 weeks, this appointment can feel like a significant milestone—it’s often the first time a detailed look at the baby’s development is possible, and for many women it’s also when they choose to find out the sex, if they’d like to know.
For women who are pregnant after 35, the anatomy scan holds the same purpose as it does for any pregnancy: to check that the baby is developing within expected parameters. Understanding what the scan looks for and how results are typically communicated may help make the experience feel less intimidating.
What the Anatomy Scan Is Designed to Assess
According to the American College of Obstetricians and Gynecologists (ACOG), the mid-pregnancy ultrasound is used to evaluate fetal anatomy in detail, assess growth, check placental position, and measure amniotic fluid levels. The sonographer typically examines the brain, spine, heart, abdominal organs, kidneys, limbs, and face.
The scan usually takes 30 to 60 minutes. In some cases, the baby’s position or movement makes it difficult to capture all the required images, and a follow-up scan may be recommended. This is a fairly common occurrence and does not typically indicate a problem.
Key Structures Examined During the Scan
The Heart and Major Vessels
The sonographer will look at the four chambers of the heart and, where possible, the major blood vessels entering and leaving it. Congenital heart conditions are among the most common birth differences, and while the anatomy scan can identify many structural heart findings, some may only become apparent later in pregnancy or after birth. If anything looks different, a follow-up with a fetal cardiologist or a more detailed echocardiogram may be recommended.
The Brain and Spine
The anatomy scan checks for conditions affecting the brain’s structure and fluid levels, including the ventricles. The spine is examined along its full length to look for neural tube differences. In most pregnancies, these structures appear within normal ranges, but any finding that warrants further evaluation will be discussed with your care team.
Abdominal Organs and Kidneys
The stomach, bowel, and kidneys are assessed for normal positioning and appearance. Mild kidney pelvis widening (pyelectasis) is one of the more commonly noted findings and often resolves on its own, though it may be monitored with follow-up scans.
Placenta Location and Amniotic Fluid
The anatomy scan also checks where the placenta is located. In some pregnancies, the placenta lies low in the uterus, a finding called placenta previa. Many cases identified at 20 weeks resolve on their own as the uterus grows, and a follow-up scan later in pregnancy is standard in this situation.
Amniotic fluid levels are measured to confirm they fall within the expected range. Both too little (oligohydramnios) and too much (polyhydramnios) fluid can be associated with various conditions, and findings outside the normal range are typically investigated further.
What “Soft Markers” Mean and How They’re Interpreted
During the anatomy scan, a sonographer may identify findings called “soft markers”—subtle features that are more common in pregnancies affected by certain chromosomal differences but that can also appear in completely typical pregnancies. Examples include an echogenic bowel, a choroid plexus cyst, or a shortened femur measurement.
The significance of these markers depends heavily on context. In isolation, many soft markers are not considered strongly predictive of chromosomal conditions, particularly in women who have already had first-trimester screening with reassuring results. Your care team will discuss any findings with you and explain what, if any, additional evaluation makes sense given the full picture of your pregnancy. Understanding how to navigate prenatal testing decisions after 35 can help you feel more prepared for these conversations.
If a Finding Is Identified
Being told that something looks different on an anatomy scan can be an anxiety-inducing experience, and it’s natural to have many questions. It may help to know that many findings identified at 20 weeks turn out to be variations of normal or resolve without intervention. Others may require follow-up scans, referral to a maternal-fetal medicine (MFM) specialist, or additional testing.
MFM specialists—sometimes called perinatologists—are OB/GYNs with additional training in high-risk pregnancies and complex fetal findings. A referral for further evaluation does not necessarily mean that something is seriously wrong, and consulting with a specialist can provide a clearer picture and more detailed information. For women who feel the emotional weight of this experience, connecting with resources around pregnancy anxiety after 35 may also offer useful support.
Preparing for the Appointment
Most anatomy scans don’t require any special preparation, though some providers ask patients to arrive with a partially full bladder. It may help to write down any questions you’d like to ask beforehand, since appointments can feel fast-paced. Many women choose to bring a partner or support person, both for practical support and to share the experience.
It’s also worth confirming with your provider’s office whether you’ll receive the results right away from the sonographer or whether the images will be reviewed and results communicated afterward, so you know what to expect at the end of the appointment.
Frequently Asked Questions
Is the anatomy scan more detailed for pregnancies after 35?
The anatomy scan itself is the same regardless of age. However, women over 35 are sometimes offered additional screening or monitoring during pregnancy, and your care team will discuss which evaluations make sense based on your individual history and any results from earlier in pregnancy.
What happens if the baby’s position makes it difficult to see everything?
This is a common occurrence and usually means a follow-up scan is scheduled to capture the remaining images. It does not typically indicate a problem with the pregnancy.
Can the anatomy scan detect all birth differences?
The anatomy scan is comprehensive but not able to detect every possible condition. Some differences may be too subtle to see at 20 weeks, may not be present until later in development, or may be outside the resolution of ultrasound imaging. Your care team can explain what the scan can and cannot assess.
Will I find out the sex at this appointment?
If the baby’s position allows and you’d like to know, the anatomy scan is typically when sex is determined via ultrasound. You can also indicate to the sonographer in advance if you prefer not to know, and they will document accordingly.
Key Takeaways
- The 20-week anatomy scan is a detailed ultrasound that assesses fetal anatomy, growth, placental position, and amniotic fluid levels.
- Key structures examined include the heart, brain, spine, abdominal organs, and kidneys—findings are interpreted in the context of the full pregnancy picture.
- “Soft markers” may be identified, but many are not strongly predictive of chromosomal conditions, especially with reassuring earlier screening.
- Follow-up scans or specialist referrals are relatively common and do not automatically indicate a serious problem.
- If you have questions after the scan, your OB/GYN or a maternal-fetal medicine specialist is well-placed to provide individualized guidance.
Medical Disclaimer
This content is for informational purposes only and does not constitute medical advice. Individual health situations vary significantly. Always consult a qualified healthcare provider before making decisions related to your health, fertility, or pregnancy.
About the Author
Emily Carter is a women’s health writer focused on fertility, pregnancy after 35, and sleep changes in midlife. She writes research-informed, non-alarmist content to help women navigate reproductive and hormonal transitions with clarity and confidence.