Fetal Anomaly Scan: Complete Guide to the Detailed Pregnancy Ultrasound
A fetal anomaly scan is one of the most detailed ultrasound examinations performed during pregnancy. It is designed to carefully asse t baby’s anatomy and development and can identify many structural abnormalities.
The scan is an important part of prenatal care and is often performed during the second trimester. It can provide valuable information about the baby’s development, placenta, amniotic fluid, and other aspects of the pregnancy.
In this guide, we explain what a fetal anomaly scan is, when it is performed, what it checks, what happens during the examination, and what different results may mean.
What Is a Fetal Anomaly Scan?
A fetal anomaly scan, sometimes called a detailed anatomy scan or 20-week ultrasound, is a specialized pregnancy ultrasound that examines the baby’s physical development in detail.
The examination looks at multiple fetal structures and organs, including the:
- Brain
- Face
- Spine
- Heart
- Chest
- Abdomen
- Stomach
- Kidneys
- Bladder
- Arms and legs
The scan may also assess:
- Placenta
- Amniotic fluid
- Fetal growth
- Fetal position
- Other pregnancy-related structures
The exact examination and timing can vary depending on the pregnancy and local clinical guidelines.
When Is the Fetal Anomaly Scan Performed?
The detailed anatomy scan is generally performed during the second trimester, commonly around 18 to 22 weeks of pregnancy.
The exact timing may vary depending on:
- Pregnancy dating
- Previous ultrasound findings
- Maternal medical history
- Fetal position
- Local clinical practice
- Whether additional assessment is required
If an earlier examination identifies a potential concern, a specialist may recommend a more detailed ultrasound at an appropriate time.
Why Is the Fetal Anomaly Scan Important?
The fetal anomaly scan provides an opportunity to examine the baby’s anatomy in greater detail than many routine pregnancy ultrasounds.
It can help doctors:
- Assess fetal anatomy
- Monitor fetal growth
- Identify many structural abnormalities
- Evaluate the fetal heart
- Examine the placenta
- Assess amniotic fluid
- Identify findings that may require additional testing or follow-up
Early identification of a potential concern allows the healthcare team to investigate it further and plan appropriate pregnancy care.
What Does the Fetal Anomaly Scan Check?
During a detailed pregnancy ultrasound, the specialist may assess several areas.
1. The Baby’s Brain
The ultrasound may examine important structures within the fetal brain.
The specialist may assess:
- Brain shape
- Ventricular system
- Midline structures
- Posterior fossa
- Other visible brain anatomy
The purpose is to look for structural findings that may require additional evaluation.
2. The Baby’s Face
The fetal face may be examined for features that can be evaluated by ultrasound.
The assessment may include:
- Facial profile
- Upper lip
- Facial structures
- Other visible features
The baby’s position can sometimes make facial assessment more difficult.
3. The Spine
The fetal spine is examined along its length to assess its development and alignment.
The specialist may evaluate:
- Spine shape
- Vertebral alignment
- Surrounding tissues
- Skin coverage
4. The Fetal Heart
The heart is one of the most important parts of the anomaly scan.
The examination may assess:
- Heart position
- Heart size
- Four-chamber view
- Major outflow tracts
- Heart rhythm
- Other visible cardiac structures
If the ultrasound shows a finding that requires more detailed assessment, a fetal echocardiogram may be recommended.
5. The Chest
The specialist may examine the fetal chest to assess:
- Lung appearance
- Diaphragm
- Position of the heart
- Other visible structures
6. The Abdomen
The abdominal examination may include assessment of:
- Stomach
- Abdominal wall
- Kidneys
- Bladder
- Umbilical cord insertion
- Other abdominal structures
The specialist also considers the relationship between different organs and their overall appearance.
7. The Arms and Legs
The fetal limbs may be examined to assess:
- Presence of the arms and legs
- Long bones
- Hands and feet when visible
- Limb movement
- General development
The baby’s position can affect how clearly certain structures can be visualized.
How Is Fetal Growth Assessed?
A fetal anomaly scan can also include measurements that help estimate fetal size.
Measurements may include:
- Head measurements
- Abdominal circumference
- Femur length
- Other biometric parameters
These measurements are compared with expected ranges for the pregnancy stage.
Growth assessment is interpreted in the context of gestational age and other clinical findings.
What About the Placenta?
The placenta is also assessed during pregnancy ultrasound.
The specialist may evaluate:
- Placental location
- Appearance
- Relationship to the cervix
- Other relevant features
If the placenta is located close to the cervix, additional follow-up may sometimes be recommended later in pregnancy.
What About Amniotic Fluid?
The amount of amniotic fluid surrounding the baby can provide useful information about pregnancy wellbeing.
The specialist may assess whether the fluid appears within the expected range.
Abnormally high or low fluid levels may require additional evaluation depending on the circumstances.
What Happens During a Fetal Anomaly Scan?
The procedure is generally straightforward.
Step 1: Preparation
Depending on the stage of pregnancy and the healthcare facility, you may receive instructions before the scan.
Step 2: Ultrasound Examination
You will usually lie comfortably while ultrasound gel is applied to the abdomen.
A transducer is then moved across the abdomen to obtain images of the baby.
Step 3: Detailed Assessment
The specialist examines the baby’s anatomy systematically.
Different views may be obtained to assess the brain, face, heart, spine, abdomen, limbs, placenta, and other structures.
Step 4: Measurements
The specialist may take several fetal measurements to assess growth.
Step 5: Results
The findings are explained and any recommended follow-up is discussed.
The duration of the examination can vary depending on fetal position, gestational age, the purpose of the scan, and whether additional assessment is required.
Can the Baby’s Position Affect the Scan?
Yes.
The baby’s position can make certain structures difficult to visualize.
For example, the baby may be facing away from the ultrasound probe or positioned in a way that limits the view of the heart or face.
If important structures cannot be assessed adequately, the healthcare professional may recommend repeating part of the examination at another time.
This does not necessarily mean that there is a problem with the baby.
What Can a Fetal Anomaly Scan Detect?
A detailed ultrasound can identify many structural abnormalities.
Depending on the condition, the scan may detect concerns involving:
- Brain development
- Spine
- Heart
- Face
- Abdomen
- Kidneys
- Limbs
- Chest
- Abdominal wall
- Placenta
However, it is important to understand that no ultrasound can detect every possible fetal condition.
Some conditions may develop later in pregnancy, while others may not be visible on ultrasound.
Does a Normal Anomaly Scan Mean Everything Is Perfect?
A normal scan is reassuring, but it cannot guarantee that the baby has no health conditions.
Ultrasound has limitations, and some conditions may not be detectable before birth.
The fetal anomaly scan should therefore be considered an important part of prenatal care rather than a complete guarantee of fetal health.
Routine antenatal follow-up remains important throughout pregnancy.
What If an Abnormality Is Found?
If the scan identifies a possible abnormality, the next step depends on the type and significance of the finding.
Your doctor may recommend:
- A repeat ultrasound
- A more detailed specialist scan
- Fetal echocardiography
- Additional prenatal screening
- Genetic counseling
- Diagnostic testing
- Consultation with another specialist
An ultrasound finding does not always mean that a serious condition is present.
Some findings may represent normal variations, while others require further investigation.
The specialist should explain the finding clearly and discuss the appropriate next steps.
Fetal Anomaly Scan vs. Routine Ultrasound
Although both use ultrasound technology, the purpose and level of detail may differ.
| Routine Pregnancy Ultrasound | Fetal Anomaly Scan |
|---|---|
| General pregnancy assessment | Detailed fetal anatomy assessment |
| May assess fetal heartbeat and growth | Systematic examination of multiple fetal structures |
| May assess placenta and fluid | Detailed assessment of fetal organs and anatomy |
| Usually shorter | May require more detailed imaging |
| Part of routine antenatal care | Specialized second-trimester assessment |
The exact scope of each examination depends on the pregnancy and the healthcare provider.
Fetal Anomaly Scan and Fetal Medicine
The fetal anomaly scan is closely connected to fetal medicine.
A fetal medicine specialist may perform or interpret detailed ultrasound examinations, particularly when there is:
- A suspected fetal abnormality
- Abnormal prenatal screening
- Fetal growth concerns
- A high-risk pregnancy
- A previous pregnancy affected by a fetal condition
- A maternal condition that may affect fetal development
Specialist assessment can provide a more detailed evaluation when additional expertise is needed.
What Is a Fetal Echocardiogram?
A fetal echocardiogram is a specialized ultrasound examination focusing specifically on the baby’s heart.
It may be recommended when:
- A heart abnormality is suspected
- There is a relevant family history
- Certain maternal conditions increase risk
- Another ultrasound shows a possible cardiac finding
- The pregnancy has another clinical indication
A fetal echocardiogram provides a more detailed assessment of the fetal heart than a standard anatomy scan.
Can the Fetal Anomaly Scan Determine the Baby’s Sex?
In many cases, the baby’s sex may be visible during the ultrasound if the fetal position allows adequate visualization.
However, the primary purpose of the anomaly scan is to assess fetal anatomy and development, not to determine sex.
The visibility of fetal sex can depend on gestational age, fetal position, image quality, and local medical practice.
How Should You Prepare for the Scan?
In most cases, detailed pregnancy ultrasound requires little preparation.
You may want to:
- Wear comfortable clothing
- Bring previous ultrasound reports
- Bring relevant medical records
- Follow any instructions provided by your healthcare provider
- Allow enough time for the examination
Your healthcare facility will provide specific preparation instructions if needed.
Questions to Ask After Your Fetal Anomaly Scan
You may want to ask:
- Is the baby’s growth appropriate for gestational age?
- Was the fetal anatomy clearly visualized?
- Is the heart assessment reassuring?
- Is the placenta in an appropriate location?
- Is the amniotic fluid within the expected range?
- Was anything unusual identified?
- Do I need another ultrasound?
- Do I need a fetal echocardiogram?
- Do I need additional prenatal screening?
- When should I have my next appointment?
Understanding the findings and follow-up plan can help you feel more informed about your pregnancy.
Fetal Anomaly Scan with Dr. Shady
A detailed fetal assessment can provide important information about fetal development and pregnancy wellbeing.
Dr. Shady Saleem provides specialized fetal medicine and pregnancy care, including detailed ultrasound assessment when clinically indicated.
Depending on the pregnancy, fetal assessment may include evaluation of fetal anatomy, growth, placenta, amniotic fluid, and other relevant findings.
When an ultrasound identifies a possible concern, additional specialist assessment or testing may be recommended based on the individual circumstances.
Frequently Asked Questions About Fetal Anomaly Scans
What is a fetal anomaly scan?
A fetal anomaly scan is a detailed pregnancy ultrasound that examines the baby’s anatomy and development, usually during the second trimester.
When is the anomaly scan performed?
It is commonly performed around 18–22 weeks of pregnancy, although the exact timing can vary depending on the pregnancy and local clinical recommendations.
Is the fetal anomaly scan safe?
Ultrasound is widely used during pregnancy when medically appropriate and performed by trained healthcare professionals.
Can an anomaly scan detect all abnormalities?
No. Ultrasound can detect many structural abnormalities, but it cannot identify every possible fetal condition.
What happens if the scan shows a possible abnormality?
Your healthcare provider may recommend additional ultrasound assessment, fetal echocardiography, genetic counseling, prenatal testing, or other specialist evaluation depending on the finding.
Does an abnormal scan always mean there is a serious problem?
No. Some ultrasound findings may be minor or represent normal variations. Further assessment is often needed before determining the significance of a finding.
Can the anomaly scan check the baby’s heart?
Yes. Assessment of the fetal heart is an important part of the detailed anatomy scan. A specialized fetal echocardiogram may be recommended when additional cardiac assessment is needed.
Conclusion
The fetal anomaly scan is an important part of prenatal care that provides a detailed assessment of the baby’s anatomy and development.
By examining structures such as the brain, heart, spine, abdomen, kidneys, limbs, placenta, and amniotic fluid, the scan can identify many potential concerns and help guide further pregnancy care when necessary.
A normal scan is reassuring, but it does not guarantee that every possible condition can be detected. Continued antenatal care and appropriate follow-up remain essential throughout pregnancy.
If you have been advised to have a fetal anomaly scan or have questions about your baby’s development, a consultation with a qualified fetal medicine specialist can help you understand the examination and its findings.
Medical Disclaimer
This article is intended for general educational purposes only and does not replace professional medical advice, diagnosis, or treatment. Pregnancy ultrasound and prenatal testing should be recommended and interpreted by a qualified healthcare professional according to each pregnancy’s individual circumstances.