20 Week Anomaly Scan: Complete Guide for Singapore Parents
The 20 week anomaly scan (also called the fetal anomaly scan or detailed scan) is a comprehensive ultrasound performed between 18-22 weeks of pregnancy that checks your baby's development and can detect up to 90% of major structural abnormalities. The sonographer examines your baby's brain, heart, spine, organs, and limbs, checks the placenta position, and can reveal the gender if you wish. In Singapore, this scan takes 30-60 minutes and costs $150-$500 depending on the hospital or clinic.
What is the 20 Week Anomaly Scan?
The 20 week anomaly scan is one of the most important milestones in your pregnancy journey. Also known as the:
- Fetal anomaly scan
- Detailed scan
- Mid-pregnancy ultrasound
- Morphology scan
- Level 2 ultrasound
This scan is typically performed between 18-22 weeks of pregnancy, so don't worry if yours is booked a bit earlier or later than exactly 20 weeks.
While much of the excitement revolves around potentially finding out whether you're having a boy or girl, this scan serves a much more important purpose: checking that your baby is developing normally and detecting any potential abnormalities early.
What the Sonographer Checks
This scan is far more detailed than your 12-week dating scan. The sonographer will systematically examine:
🧠 Baby's Brain
- Brain structure and development
- Ventricles (fluid-filled spaces)
- Cerebellum
💗 Baby's Heart
- Four chambers of the heart
- Heart rhythm and rate
- Major blood vessels
🧬 Spine and Skeleton
- Spine alignment
- Arms and legs
- Hands and feet (including counting fingers and toes)
👁 Face
- Facial profile
- Lips (checking for cleft lip)
- Eye sockets
🧸 Internal Organs
- Stomach
- Kidneys
- Bladder
- Abdominal wall
- Diaphragm
📐 Measurements Taken
- Head circumference (HC)
- Biparietal diameter (BPD) - width of head
- Abdominal circumference (AC)
- Femur length (FL) - thigh bone
🍁 Placenta and Amniotic Fluid
- Placenta position - checking if it's lying low (placenta praevia)
- Amniotic fluid levels
- Umbilical cord - confirming 3 vessels
What Happens During the Scan
Here's what to expect during your 20 week anomaly scan:
Before the Scan
- You'll be asked to lie on a padded examination table
- The room will be dimmed to see the screen better
- You'll need to expose your belly (the sonographer will tuck tissue into your waistband to protect your clothes)
During the Scan
- Warm gel is applied to your tummy
- The sonographer moves the ultrasound probe across your abdomen
- They'll methodically check all the structures mentioned above
- You can watch on the screen and ask questions
- The sonographer may need to press firmly at times to get clear images
How Long Does It Take?
Expect the scan to take 30 minutes to 1 hour - much longer than your 12-week scan because there's so much more to examine.
After the Scan
The sonographer will talk you through their findings during the scan. They'll then refer you to your gynaecologist for further explanations. Don't be afraid to ask questions during the scan - if you don't ask now, you may not have another chance!
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Claim Free Gift →Finding Out the Gender: Boy or Girl?
The 20 week scan is typically when parents can find out their baby's gender - if they want to know!
Tell the Sonographer First
At the start of your scan, tell the sonographer whether you want to know the gender or keep it a surprise. If you don't want to know, they'll warn you before looking at that area so you can look away.
What Do Boy and Girl Parts Look Like?
- Girl: Appears as three parallel lines (the labia)
- Boy: Shows a visible protrusion (penis and sometimes scrotum)
Gender Accuracy
At 20 weeks, gender determination is usually very accurate (over 95%). However, it depends on:
- Baby's position during the scan
- Whether legs are open or crossed
- The sonographer's experience
How to Prepare for Your 20 Week Scan
Do I Need a Full Bladder?
Unlike your 12-week scan, you usually don't need a full bladder for the 20-week anomaly scan. Your baby is now large enough to see clearly without it. However, some clinics may still request it, so check with your healthcare provider beforehand.
Preparation Checklist
- ✅ Confirm your appointment time and location
- ✅ Check if you need a full bladder (ask your clinic)
- ✅ Bring your partner or support person
- ✅ Prepare questions you want to ask
- ✅ Decide if you want to know the gender
- ✅ Bring previous scan reports if requested
What to Wear to Your Scan
Choose your outfit carefully for comfort and practicality:
✅ DO Wear:
- A loose-fitting top that can be easily pulled up
- Comfortable pants or skirt with an elastic waistband that can be pulled down slightly
- Separate top and bottom pieces
❌ DON'T Wear:
- A dress or jumpsuit - you'd have to pull it up to your chest!
- Tight jeans or pants with difficult buttons/zips
- A bodysuit or tucked-in top
Can My Partner Attend the Scan?
Yes! Most clinics and hospitals in Singapore allow one support person (usually your partner) to attend the 20 week scan with you.
Why Partners Should Attend
- It's a special bonding moment - seeing your baby together
- Two pairs of ears to hear the findings
- Emotional support if any concerns arise
- Partners often feel more connected to the pregnancy after seeing the scan
For Dads/Partners
This is your chance to "meet" your baby! Ask questions, take photos if allowed, and be present in the moment. Many dads say the 20-week scan is when the pregnancy became "real" for them.
What If They Find Something?
It's natural to feel anxious about what the scan might reveal. Here's what you should know:
Most Scans Are Normal
The vast majority of 20-week scans show a healthy, normally developing baby. Try to relax and enjoy seeing your little one!
If an Abnormality is Detected
If the sonographer finds something concerning:
- They may call in a senior sonographer or doctor for a second look
- You may be referred for further tests (additional scans, amniocentesis, etc.)
- You'll be referred to a Maternal Fetal Medicine (MFM) specialist
- Counselling and support will be provided
Common "Soft Markers"
Sometimes scans show "soft markers" - minor findings that may indicate a slightly increased risk but are often harmless:
- Echogenic bowel
- Choroid plexus cysts
- Single umbilical artery
- Echogenic intracardiac focus (EIF)
If found in isolation (without other markers), these usually require no action. Your doctor will explain what any findings mean for your specific situation.
What the Scan Cannot Detect
While powerful, the 20-week scan cannot detect everything. It cannot diagnose:
- Chromosomal conditions like Down syndrome (requires blood tests or amniocentesis)
- Autism or learning difficulties
- Some heart defects that develop later
- Conditions that only become apparent after birth
Cost of 20 Week Scan in Singapore
Here's what to expect for the 20 week anomaly scan cost in Singapore:
Public Hospitals
| Hospital | Estimated Cost |
|---|---|
| KK Women's and Children's Hospital | $150 - $250 |
| NUH (National University Hospital) | $150 - $250 |
| SGH (Singapore General Hospital) | $150 - $250 |
Private Clinics & Hospitals
| Type | Estimated Cost |
|---|---|
| Private O&G Clinics | $250 - $400 |
| Private Hospitals (Thomson, Mount E) | $300 - $500 |
| MFM Specialist Detailed Scan | $400 - $600+ |
Medisave
Good news! Prenatal ultrasound scans are claimable under Medisave in Singapore. Check with your clinic about using Medisave for your scan.
Frequently Asked Questions
What is a 20 week anomaly scan?
The 20 week anomaly scan (also called the fetal anomaly scan, detailed scan, or mid-pregnancy ultrasound) is a comprehensive ultrasound examination performed between 18-22 weeks of pregnancy. It checks your baby's development, detects up to 90% of major structural abnormalities, confirms placenta position, and can reveal your baby's gender if desired.
What does the sonographer check during a 20 week scan?
The sonographer examines your baby's brain, heart, spine, face, kidneys, abdomen, limbs, hands and feet. They measure the head circumference, check organ development, look for conditions like cleft lip, confirm placenta position, assess amniotic fluid levels, and verify the heartbeat and number of babies.
Can you find out the gender at 20 week scan?
Yes, the 20 week anomaly scan is usually when parents can find out their baby's gender if they wish. Girl parts appear as three lines on ultrasound, while boy parts typically show a visible protrusion. Tell your sonographer at the start whether you want to know or keep it a surprise.
How much does a 20 week scan cost in Singapore?
In Singapore, the 20 week anomaly scan typically costs $150-$300 at public hospitals (KKH, NUH) and $250-$500 at private clinics. The detailed fetal anomaly scan by a specialist (MFM) may cost more. Most scans are partially covered by Medisave.
Do I need a full bladder for 20 week scan?
Unlike the 12-week scan, you usually don't need a full bladder for the 20-week anomaly scan as your baby is now larger and easier to see. However, some clinics may still request it, so check with your healthcare provider beforehand.
How long does the 20 week anomaly scan take?
The 20 week anomaly scan typically takes 30 minutes to 1 hour. It's longer than earlier scans because the sonographer needs to examine many detailed measurements and structures. If your baby is in an awkward position, you may be asked to walk around and return for better images.
Is the 20 week scan safe for my baby?
Yes, ultrasound scans are considered safe and have been used in pregnancy for decades. They use sound waves, not radiation. There are no known risks to mother or baby from routine ultrasound examinations.
What if my baby is in a difficult position?
If your baby isn't cooperating, the sonographer may ask you to walk around, drink cold water, or lie on your side. In some cases, you may need to return for a follow-up scan to complete the examination. This is completely normal and nothing to worry about.
Can my husband attend the 20 week scan in Singapore?
Yes, most clinics and hospitals in Singapore allow one support person (usually your partner) to attend the anomaly scan. Check with your specific clinic about their policy, especially regarding any current visitor restrictions.