Pregnancy ultrasound is not one scan. It is a short series of scans, each timed to a window when a particular thing can be checked properly. Done too early or too late, a scan simply cannot answer the question it was meant to answer.
This page sets out the usual schedule, what each scan looks at, and why the timing matters. Scans at ShivAnuj Diagnostic Center, Harni–Warasiya Ring Road, Vadodara, are performed and reported by Dr. Shivani Kodnani (MD Radiodiagnosis, DNB, MNAMS, gold medalist) on a Mindray Resona i9 AI-powered ultrasound system.
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The usual scan schedule
Weeks are counted from the first day of your last menstrual period, not from conception. Your own schedule may differ — your obstetrician may add scans, and some are only done if indicated.
| Scan | When | What it checks |
|---|---|---|
| Early / viability scan | 6–9 weeks | Confirms pregnancy is inside the uterus, heartbeat, number of babies. Often done if there is pain, bleeding or uncertain dates. |
| Dating scan | 8–12 weeks | Establishes the due date, which is most accurate in the first trimester. |
| NT scan (nuchal translucency) | 11 weeks to 13 weeks 6 days | Measures fluid at the back of the baby's neck as part of first-trimester screening, usually combined with a blood test. The window is strict. |
| Anomaly scan (TIFA / level II) | 18–22 weeks (commonly 19–20) | A detailed, structured examination of the baby's anatomy: brain, face, spine, heart, abdomen, kidneys, limbs, plus placenta and amniotic fluid. |
| Growth scan | 28–34 weeks (may repeat) | Estimates the baby's weight and growth trend, checks fluid and placental position. Doppler may be added. |
| Well-being / term scan | 36 weeks onward | Position of the baby, fluid, growth and Doppler before delivery, if indicated. |
Anomaly scan and TIFA — are they the same thing?
In practice, yes. TIFA stands for Targeted Imaging for Fetal Anomalies. It is the detailed second-trimester anatomy scan, the same examination many people call the anomaly scan or level II scan. Occasionally a further, more focused scan is requested when something needs a closer look, or when a fetal medicine or fetal echocardiography opinion is sought.
Why 18–22 weeks: before about 18 weeks many structures are too small to assess reliably; much after 22 weeks the baby is more crowded and bone shadowing makes some views harder. This window is the practical compromise.
What happens after the anomaly scan?
This is one of the most common questions we are asked. If the anomaly scan is normal and the pregnancy is uncomplicated, the next routine scan is usually the growth scan at around 28–32 weeks. If something needs monitoring — growth, fluid, placental position, a finding that warrants review — your obstetrician will schedule an interval scan sooner and tell you why.
3D, 4D and 5D scans
Standard obstetric scanning is 2D, and 2D is what the medical assessment is based on. 3D produces a surface rendering, and 4D shows that rendering moving. They can occasionally help demonstrate a surface finding such as a facial cleft, and many parents value the images, but they are an addition to the anatomy scan, not a replacement for it. Image quality depends on fluid around the baby and the baby's position, so a clear face view can never be promised.
Preparation
- Early scans: a comfortably full bladder helps. Drink water and avoid emptying your bladder shortly before.
- Later scans: no special preparation; a full bladder is usually not needed.
- Wear two-piece clothing so the abdomen is easy to access.
- Bring your previous scans, reports and your antenatal card. Comparison with earlier scans is part of the assessment.
- Allow extra time for an anomaly scan — it is detailed, and it may be paused if the baby is in an awkward position.
Is ultrasound safe in pregnancy?
Diagnostic ultrasound uses sound waves, not ionising radiation, and has been used in pregnancy for decades with no established harm when performed for a medical reason by trained staff. Scans are performed using the lowest exposure needed to get the required information. For that reason, non-medical “keepsake” scanning is not encouraged.
A legal note (PCPNDT Act): determining or disclosing the sex of a fetus is a criminal offence in India. We do not reveal the sex of the baby under any circumstances, and we are required to complete Form F for every obstetric scan. Please do not ask the staff or the doctor — the answer will always be no.
Questions patients ask
How many scans are done in a normal pregnancy?
Commonly three to five: a dating or early scan, the NT scan, the anomaly scan at 18–22 weeks, and one or more growth scans in the third trimester. Your obstetrician decides the schedule for your pregnancy.
When exactly should the anomaly scan be done?
Between 18 and 22 weeks, most often at 19–20 weeks. Earlier than 18 weeks many structures are too small to assess properly.
What is the next scan after the TIFA scan?
In an uncomplicated pregnancy, usually the growth scan at around 28–32 weeks. If anything needs watching, your obstetrician will arrange an earlier interval scan.
Will you tell me the baby's sex?
No. Disclosing fetal sex is prohibited by law in India under the PCPNDT Act. This applies to every centre and there are no exceptions.
Do I need a full bladder?
For early first-trimester scans, yes — it improves the view. For second- and third-trimester scans it is usually not necessary.
Do I need an appointment, or a doctor's referral?
Please call +91 94289 74800 to book, particularly for the anomaly scan, which needs a longer slot. Bring your referral and previous reports.
Is a 4D scan better than a normal scan?
Not for the medical assessment. The anatomy is evaluated on 2D images. 3D, 4D and 5D add surface views that parents often like and that occasionally help with specific findings.
How long does the anomaly scan take?
Typically 30–45 minutes, sometimes longer if the baby is lying awkwardly and we need to wait for it to move.
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This page is general health information, not a substitute for a clinical examination. Suitability for any procedure is decided only after an in-person assessment. Individual results vary.