An anomaly scan in pregnancy is a detailed ultrasound that checks your baby’s growth and development and looks for structural concerns.
Pregnancy involves many scans and tests.
Some confirm the pregnancy.
Some estimate the risk of genetic conditions.
Others monitor growth and development.
Quick Answer
An anomaly scan is a detailed pregnancy ultrasound usually performed between 18 and 22 weeks of pregnancy. It evaluates your baby’s anatomy, including the brain, heart, spine, kidneys, limbs, placenta, and other major structures. The scan can detect many structural abnormalities before birth, making it one of the most important routine ultrasounds during pregnancy.
But if there is one ultrasound that many specialists consider the most important routine scan during pregnancy, it is the anomaly scan.
Often performed between 18 and 22 weeks of pregnancy, the anomaly scan provides one of the most detailed assessments of your baby’s anatomy before birth.
For many parents, this appointment is exciting because they get another opportunity to see their baby.
For healthcare providers, however, the scan serves a much bigger purpose.
It helps evaluate how the baby is developing and can identify many structural abnormalities that may require additional monitoring or care.
Key Takeaways
- The anomaly scan is usually performed between 18 and 22 weeks of pregnancy.
- It is one of the most detailed routine ultrasounds performed during pregnancy.
- The scan evaluates major fetal organs and body systems.
- Many structural abnormalities can be detected during the anomaly scan.
- The heart, brain, spine, kidneys, limbs, and placenta are carefully examined.
- A normal anomaly scan is reassuring but cannot guarantee the absence of every condition.
- Some abnormalities may require additional imaging or specialist evaluation.
- The scan helps healthcare providers plan appropriate pregnancy care.
- Most anomaly scan results are normal and reassuring.
- The anomaly scan is an important milestone in prenatal care.
What Is An Anomaly Scan?
An anomaly scan, sometimes called a:
- Mid-pregnancy scan
- Detailed ultrasound scan
- Level II ultrasound
- Anatomy scan
is a comprehensive ultrasound examination performed during the second trimester.
Unlike earlier scans that focus primarily on confirming pregnancy or estimating due dates, the anomaly scan is designed to examine the baby’s anatomy in detail.
According to the International Society of Ultrasound in Obstetrics and Gynecology (ISUOG),
the routine mid-trimester ultrasound scan is performed mainly for anatomical evaluation of the fetus and can detect many clinically important structural abnormalities when performed appropriately. (Salomon et al. 2022)
Why Is The Anomaly Scan Considered So Important?
During the first trimester, many organs are still developing.
By the middle of pregnancy, fetal anatomy is much easier to visualize.
This allows sonographers and fetal medicine specialists to examine structures that could not be assessed adequately earlier.
The anomaly scan provides important information about:
- Brain development
- Facial structures
- Spine
- Heart
- Stomach
- Kidneys
- Bladder
- Limbs
- Placenta
- Umbilical cord
Because it evaluates multiple organ systems during a single examination,
the anomaly scan is often regarded as one of the most comprehensive routine assessments performed during pregnancy.
When Is The Anomaly Scan Performed?
The anomaly scan is usually performed between 18 and 22 weeks of pregnancy.
This timing is carefully chosen.
At this stage:
- The baby is large enough for detailed assessment.
- Many organs can be visualized clearly.
- Structural abnormalities are easier to identify.
- There is sufficient amniotic fluid to improve imaging quality.
ISUOG guidelines recommend performing the routine mid-trimester ultrasound during this period because it provides optimal conditions for evaluating fetal anatomy. (Salomon et al. 2011)
What Happens During The Scan?
The procedure is similar to a standard pregnancy ultrasound.
A clear gel is applied to the abdomen.
The sonographer then moves an ultrasound probe across the skin to obtain images of the baby.
Most anomaly scans take approximately 20-45 minutes.
The exact duration depends on:
- Fetal position
- Maternal body habitus
- Image quality
- Whether additional measurements are required
Sometimes the baby may be lying in a position that makes certain structures difficult to see.
If this happens, the sonographer may ask the mother to:
- Change position
- Walk for a few minutes
- Return later for repeat imaging
This is very common and usually does not indicate a problem.
What Does The Sonographer Look For?
One of the biggest misconceptions is that the anomaly scan is simply a “gender reveal ultrasound.”
In reality, determining the baby’s sex is only a small part of the examination.
The primary purpose is a systematic evaluation of fetal anatomy.
Healthcare professionals typically assess:
The Brain
The scan examines key brain structures to ensure they appear to be developing appropriately.
The Face
The sonographer evaluates facial anatomy and may identify certain abnormalities involving the lips or facial structures.
The Spine
The spinal column is examined for continuity and normal appearance.
The Heart
The heart is one of the most important organs assessed during the anomaly scan.
Special ultrasound views help evaluate cardiac structure and blood flow patterns.
The Abdomen
Structures such as the stomach, kidneys, bladder, and abdominal wall are assessed.
The Limbs
The arms, hands, legs, and feet are examined for normal development.
The Placenta
The scan evaluates placental position and appearance.
Amniotic Fluid
The amount of amniotic fluid surrounding the baby is also assessed.
Can The Anomaly Scan Detect Birth Defects?
Yes, many structural abnormalities can be identified during the anomaly scan.
However, it is important to maintain realistic expectations.
No ultrasound can detect every condition before birth.
ISUOG guidance emphasizes that while many clinically important structural anomalies can be detected during routine mid-trimester ultrasound examinations,
some conditions may not be visible at the time of scanning or may develop later in pregnancy.
The ability to detect abnormalities depends on factors such as:
- Type of condition
- Gestational age
- Fetal position
- Maternal factors
- Ultrasound equipment
- Sonographer expertise
Understanding these limitations helps parents interpret results more accurately.
What Types Of Conditions May Be Identified?
The anomaly scan may help identify certain structural abnormalities involving:
- The brain
- Heart
- Spine
- Kidneys
- Abdomen
- Limbs
- Facial structures
Research has shown that routine ultrasound examinations can identify many severe fetal abnormalities when standardized protocols are followed. (Syngelaki A et al. 2019)
A Common Misunderstanding
Many parents believe:
If my anomaly scan is normal, my baby definitely does not have any health problems.
Unfortunately, medicine is not that simple.
A normal anomaly scan is highly reassuring.
However, no prenatal test can guarantee that every medical condition has been excluded.
Some abnormalities:
- Are too subtle to detect during pregnancy.
- Develop later in gestation.
- Involve genetic conditions without visible structural findings.
This is why healthcare providers describe the anomaly scan as a powerful screening and assessment tool rather than a guarantee of perfect health.
What Parents Usually Remember Most
Although the medical purpose of the anomaly scan is detailed fetal assessment, many parents remember something else entirely.
For the first time, they may clearly see:
- Tiny fingers
- Toes
- Facial features
- Movements
- Expressions
The experience often transforms pregnancy from an abstract idea into something much more real.
And while the technology behind the scan is remarkable, its true value lies in helping healthcare providers support the healthiest possible pregnancy.
What Happens If The Anomaly Scan Finds Something Unexpected?
For many parents, the possibility of receiving unexpected news during the anomaly scan can be worrying.
Fortunately, most anomaly scans are reassuring.
However, sometimes the sonographer may identify a finding that requires additional evaluation.
This does not automatically mean that there is a serious problem.
In many cases, further assessment is recommended simply because:
- The baby was not in an ideal position
- Certain structures could not be visualized clearly
- Additional images are needed
- A variation from typical development was observed
The purpose of follow-up testing is to gather more information rather than make assumptions.
What Are Soft Markers?
One term that occasionally arises during prenatal ultrasound discussions is “soft marker.”
Soft markers are ultrasound findings that may be associated with an increased likelihood of certain chromosomal abnormalities.
Importantly, a soft marker is not a birth defect.
Many babies with soft markers are completely healthy.
Examples may include:
- Mildly increased nuchal fold thickness
- Echogenic intracardiac focus
- Mild renal pelvic dilation
- Echogenic bowel
When soft markers are identified, healthcare providers evaluate them alongside:
- Previous screening results
- Maternal age
- Medical history
- Other ultrasound findings
A single isolated soft marker often has limited significance when no other concerns are present.
Can The Anomaly Scan Detect Down Syndrome?
This is one of the most common questions parents ask.
The answer is:
Sometimes, but not definitively.
Certain ultrasound findings may increase suspicion for Down syndrome.
However, the anomaly scan is not designed to diagnose chromosomal conditions.
Down syndrome is caused by an extra copy of chromosome 21, and diagnosis generally requires genetic testing.
The anomaly scan may identify:
- Structural abnormalities
- Soft markers
- Features associated with chromosomal conditions
But ultrasound findings alone cannot confirm Down syndrome.
This is why healthcare providers may recommend additional testing when concerns arise.
Can The Anomaly Scan Detect Every Birth Defect?
No.
This is one of the most important limitations for parents to understand.
The anomaly scan is extremely valuable, but it is not perfect.
According to ISUOG guidelines, many clinically important structural abnormalities can be detected during routine mid-trimester ultrasound examinations, but not all abnormalities will be visible before birth. (Salomon et al. 2022)
Some conditions:
- May develop later in pregnancy
- Are too subtle to identify on ultrasound
- Involve genetic changes without structural abnormalities
- Cannot currently be visualized using ultrasound technology
This is why healthcare providers view ultrasound as an important assessment tool rather than a guarantee.
What Happens After An Abnormal Finding?
The next step depends entirely on what was identified.
Possible recommendations may include:
Repeat Ultrasound
A follow-up scan may provide clearer images or monitor a finding over time.
Fetal Echocardiography
A specialized examination of the baby’s heart.
Genetic Counseling
A genetics specialist can help explain findings and discuss available testing options.
Additional Screening
Further blood tests or non-invasive screening may be recommended.
Diagnostic Testing
Procedures such as amniocentesis may be discussed in selected situations.
The goal is always to improve understanding and support informed decision-making.
Why Early Detection Matters
Finding a condition before birth does not necessarily change the outcome.
However, it often changes how healthcare providers plan care.
Research shows that prenatal detection of major fetal abnormalities can help healthcare teams prepare for delivery, neonatal care, specialist involvement, and postnatal treatment when necessary. (Syngelaki et al. 2019)
This is one reason the anomaly scan is considered such an important milestone during pregnancy.
| Area Examined | Purpose |
|---|---|
| Brain | Assess neurological development |
| Heart | Evaluate cardiac structure |
| Spine | Check spinal development |
| Face | Assess facial structures |
| Kidneys & Bladder | Evaluate urinary system |
| Limbs | Assess arms, legs, hands and feet |
| Placenta | Assess placental location and appearance |
| Amniotic Fluid | Evaluate fetal environment |
Common Myths About The Anomaly Scan
Myth 1: The Scan Is Only For Finding Out The Baby’s Sex
False.
The primary purpose of the anomaly scan is detailed assessment of fetal anatomy.
Gender identification is only a small part of the examination.
Myth 2: A Normal Scan Guarantees A Healthy Baby
False.
A normal scan is highly reassuring, but no prenatal test can rule out every medical condition.
Myth 3: The Scan Can Diagnose Every Genetic Disorder
False.
Many genetic conditions cannot be diagnosed through ultrasound alone.
Some require genetic screening or diagnostic testing.
Myth 4: Additional Testing Means Something Is Seriously Wrong
False.
Additional testing is often recommended simply to obtain more information or better-quality images.
Many follow-up assessments ultimately produce reassuring results.
What My Patients Often Ask
“Should I Be Nervous About My Anomaly Scan?”
Feeling nervous is completely normal.
Most anomaly scans are reassuring and confirm healthy fetal development.
The purpose of the scan is to gather information, not to look for problems unnecessarily.
“Can I Bring My Partner To The Appointment?”
Policies vary between healthcare facilities.
Many centers welcome partners or support persons, but it is always best to check beforehand.
“What If My Baby Won’t Cooperate During The Scan?”
This happens more often than people realize.
Babies frequently change position, curl up, or hide certain structures.
Additional images may be obtained later if necessary.
“Will The Sonographer Tell Me The Results Immediately?”
Practices vary.
Some sonographers provide information during the scan, while others send the findings to your healthcare provider for discussion.
A Note From A Physiotherapist
One thing I often notice when speaking with expectant parents is how much pressure they place on a single appointment.
Many arrive at the anomaly scan believing that the entire pregnancy depends on what happens during those 30 or 40 minutes.
The reality is much more balanced.
The anomaly scan is incredibly valuable.
It provides detailed information about fetal development and can identify many important conditions.
But it is only one part of prenatal care.
Your overall pregnancy health depends on many factors, including nutrition, physical activity, medical monitoring, emotional well-being, and ongoing communication with your healthcare team.
The anomaly scan provides information.
It does not define the entire pregnancy journey.
What The Anomaly Scan Cannot Tell You
Even the most detailed ultrasound cannot predict:
- Personality
- Intelligence
- Talents
- Emotional development
- Future academic ability
- Every future health condition
Parents sometimes forget this because modern technology feels so advanced.
Yet pregnancy still contains uncertainty.
And that uncertainty is completely normal.
One Less Thing To Worry About
Many women spend weeks worrying about the anomaly scan.
They imagine worst-case scenarios.
They read alarming stories online.
They convince themselves that every small symptom means something is wrong.
In reality, most anomaly scans are reassuring.
Most babies show normal growth and development.
Most parents leave the appointment feeling relieved and excited.
If Nobody Has Told You This Today…
You do not need to understand every ultrasound measurement or medical abbreviation.
You do not need to become an expert in fetal medicine.
You simply need accurate information, trusted healthcare guidance, and the confidence to ask questions when something is unclear.
That is enough.
In One Sentence
The anomaly scan is the most detailed routine pregnancy ultrasound and helps assess how your baby is developing before birth.
Final Thoughts
The anomaly scan is often considered the most important routine ultrasound performed during pregnancy,
because it provides a detailed assessment of fetal anatomy during a critical stage of development.
Performed between 18 and 22 weeks, the scan helps healthcare providers evaluate major organ systems,
identify many structural abnormalities, assess placental position, and monitor overall fetal development.
Although the anomaly scan cannot detect every condition before birth,
international ultrasound guidelines support its use as one of the most valuable tools in modern prenatal care. (Zile-Velika et al. 2023)
The most important thing to remember is this:
The anomaly scan is one of the most powerful pregnancy ultrasounds available,
but its greatest value lies in providing information that helps healthcare providers support both mother and baby throughout the remainder of the pregnancy.
Frequently Asked Questions About Anomaly Scans
What is an anomaly scan?
An anomaly scan is a detailed ultrasound examination performed during the second trimester to assess fetal anatomy and development.
When is the anomaly scan performed?
Most anomaly scans are performed between 18 and 22 weeks of pregnancy.
Can the anomaly scan detect birth defects?
The scan can identify many structural abnormalities, but it cannot detect every birth defect or medical condition.
How long does an anomaly scan take?
Most scans take between 20 and 45 minutes, depending on fetal position and image quality.
Can the anomaly scan detect Down syndrome?
The scan may identify markers associated with Down syndrome, but it cannot diagnose the condition. Additional testing may be required.
Is the anomaly scan safe for my baby?
Ultrasound examinations are widely used during pregnancy and are generally considered safe when performed appropriately.
What happens if an abnormality is found?
Your healthcare provider may recommend additional ultrasound examinations, genetic counseling, fetal echocardiography, or other tests depending on the findings.
Can a normal anomaly scan guarantee a healthy baby?
No. A normal scan is highly reassuring but cannot rule out every genetic, developmental, or medical condition.
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Medical Disclaimer!
This article has been reviewed and written under the guidance of our Head Physiotherapist, Dr. Kruti Raj (PT, MUHS,CPT,CMPT). The information shared is intended for educational purposes only and should not be considered a substitute for personalized medical advice, diagnosis, or treatment.
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