Among all the scans in pregnancy, the anomaly scan stands out as the most detailed and reassuring. Often done between 18 to 22 weeks of pregnancy, this scan is far more important than you think. It gives us a peak on how is your baby is developing ?
This is the moment we get to look closely at every little part of your growing baby, from head to toe, and even peek into how the placenta and uterus are functioning.
What is an Anomaly Scan?
The anomaly scan, also known as the mid-trimester scan or level 2 ultrasound, is a comprehensive ultrasound where we:
- Measure fetal growth parameters like head circumference, abdominal circumference, and femur length.
- Examine each organ system in detail — the brain, spine, heart, stomach, kidneys, limbs, and more.
- Look at the placenta, amniotic fluid, and umbilical cord to ensure everything is supporting the baby well.
Why is it Done?
This scan helps in:
- Detecting major structural abnormalities early
- Assessing fetal growth patterns
- Evaluating placental location and uterine environment
- Checking for soft markers that may indicate a risk of chromosomal conditions
- Measuring uterine artery blood flow, which can help us assess the risk of pre-eclampsia later in pregnancy
What is Uterine Artery Doppler?
Similar to NT scan, uterine artery dopplers are assessed in anomaly scan.
We study the blood flow from the mother to the placenta. Abnormal flow patterns in the uterine artery helps us in predicting complications like:
- Pre-eclampsia (Increased blood pressure in pregnancy)
- Fetal growth restriction (decrease in baby’s weight)
This gives us a chance to monitor more closely and plan preventive strategies, like starting low-dose aspirin in high-risk mothers.
How Long Does the Anomaly Scan Take?
Typically, the scan takes 30 to 45 minutes. But it can take longer depending on several factors:
- Fetal position – If the baby is lying in a position where some parts cannot be visualized properly (like facing down or curled up), we might have to wait, or ask you to move around.
- Maternal factors – Abdominal wall thickness, a full or empty bladder, or the presence of uterine fibroids may affect the clarity of the scan.
- Amniotic fluid – Too little fluid can make it harder to see things clearly.
In some cases, if we cannot complete the structural survey due to these reasons, you may be asked to come back another day to complete the scan. This is quite normal and done to ensure nothing is missed.
“If your doctor spends extra time repositioning the probe or even asks you to return another day, it’s not because they enjoy prolonging the scan — it’s because they’re genuinely invested in getting the best possible view of your baby. It may feel like a test of patience, but in reality, it’s a sign of thoroughness. So the next time this happens, take it as a compliment — your doctor cares a little too much, and that’s exactly who you want looking after your baby.”
What Should You Expect During the Scan?
- It is done through the mother’s abdomen using a transducer.
- Partners are usually allowed to join – and it’s one of the most beautiful moments to bond with your baby! [Note:- In the State of Karnataka, NO partner or any relatives are not allowed inside the scan room; under PCPNDT Act.]
- You’ll see your baby moving, kicking, sucking, and even waving at you sometimes!
Understanding the Limitations: How Accurate is the Anomaly Scan?
The anomaly scan is highly detailed, but it’s important to remember that it has its limitations:
- Some anomalies may not be visible at 20 weeks because certain organs are still developing.
- For example, the bowels mature later in pregnancy. So certain intestinal problems like bowel atresias may only be detected in third-trimester growth scans.
- Similarly, some neurological conditions may evolve only after 24–28 weeks.
- Mild abnormalities may also go undetected due to resolution limits or if the baby’s position hides a structure.
It is a snapshot of fetal development at that point in time. Continued follow-up with growth scans and clinical observation is vital.
Final Thoughts
The anomaly scan is a milestone in your pregnancy journey — not just to see how your baby is doing, but to ensure we’re moving in the right direction. It gives us a window into your baby’s world and helps us plan better if anything needs attention.
So come for the scan with curiosity and openness. If the scan needs to be repeated, don’t worry — it’s just us making sure we do a thorough job.
Consult your Fetal medicine Specialist for any doubts or queries.
If you’re a dad reading this, remember: your involvement during these moments can mean the world to your partner — and to your growing baby.