Anomaly Scan vs Normal Pregnancy Ultrasound: Key Differences

By the time a woman reaches her fifth month, she has usually had a few scans already. Then her doctor mentions an "anomaly scan" or a "TIFFA", and the natural question follows. Wasn't that what the earlier ones were for? They weren't. A routine ultrasound and an anomaly scan use the same machine but serve different purposes, and knowing the difference helps you go into the appointment prepared.

What does a normal pregnancy ultrasound cover?

Routine scans each have a narrow, practical job that changes as the pregnancy moves along.

An early dating or viability scan confirms the pregnancy is in the uterus, checks the heartbeat and works out how many weeks you are. Later, a growth scan estimates the baby's size, the amount of fluid and the position, sometimes with Doppler to check blood flow. A quick scan may also be done to see where the placenta lies or whether the baby is head down.

All of this is useful. None of it involves going through the baby organ by organ.

What does an anomaly scan do differently?

An anomaly scan, commonly called a TIFFA scan in India, asks whether the baby's organs and body structures are forming as expected. The examiner follows a fixed sequence of views, covering the brain, face, spine, heart, abdomen, kidneys and limbs, and also reviews the placenta, cord and amniotic fluid.

Expect it to take noticeably longer than a routine scan. The examiner may pause often, wait for the baby to change position, or ask you to move or walk around for a few minutes. That is normal and usually just about getting a clear view.

Anomaly scan vs routine ultrasound at a glance

Why the timing and the examiner both matter

Around 20 weeks, the baby is big enough for most structures to be seen well, and there is still enough fluid to give clear windows. Scan much earlier and some organs are too small to assess. Scan much later and the baby's position and growing bones can get in the way.

The person holding the probe matters just as much. Recognising a subtle finding depends on obtaining the right views, which is why this scan is best done by a doctor or sonographer trained in detailed obstetric imaging.

Can a normal anomaly scan replace other scans?

No, and this is where parents are often caught out. A normal report is truly reassuring, but ultrasound has limits. Some conditions are too subtle to see, and some only appear later in pregnancy. Growth scans may still be advised afterwards, particularly if there are concerns about the baby's size or your own health.

Occasionally the baby's position, or the mother's body build, limits the views and a repeat visit is requested. It is a common request and rarely a sign that something is wrong.

When might a specialist-level scan be advised?

Most pregnancies need nothing more than routine scans and a well-timed anomaly scan. Your obstetrician may suggest a fetal medicine assessment if you have a family history of a genetic or structural condition, are expecting twins, had an affected pregnancy before, received an unexpected screening result, or had a finding on an earlier scan that needs clarifying.

Parents looking for a fetal medicine opinion in Trichy can consult Trichy Fetal Medicine and Fertility Centre, which offers detailed scans and genetic counselling.

The takeaway

Think of pregnancy scans as different tools, each built for its own question. If you are unsure why one has been advised, ask before the appointment rather than after. Parents who know what the scan will look at tend to walk in far calmer.

For appointments, the anomaly scan page has the details, and our fetal medicine specialists can advise whether it fits your situation.

Related guides

• Can an Anomaly Scan Detect All Birth Defects?
• What Does an Anomaly Scan Check in the Baby?
• Fetal Echo vs Anomaly Scan: What's the Difference?