Why the 18–22 week window matters
The anomaly scan is the single most comprehensive structural ultrasound performed during pregnancy. FOGSI and ISUOG guidance places the ideal window at 18 to 22 weeks: before 18 weeks, the baby's organs are often too small to assess in full detail; scanning much later narrows the time available for further evaluation or specialist referral if any finding needs a closer look.
Many centres use a structured scanning protocol that steps through the fetal spine, head, chest, abdomen, pelvis, limbs and face in a fixed sequence, alongside two real-time sweeps to confirm the baby's position, heartbeat, and overall orientation. This systematic approach — rather than a quick freehand look — is what makes the scan reliable.
What the anomaly scan checks
The scan examines the baby's anatomy system by system. A typical examination covers:
Brain & head
Skull shape, brain ventricles, cerebellum, and midline structures
Spine
Full spine checked for alignment and skin covering
Face
Profile, lips and upper jaw, orbits
Heart
Four chambers, outflow tracts, and rhythm
Abdomen
Stomach, bowel, abdominal wall and cord insertion
Kidneys & bladder
Kidney structure and urine-filled bladder
Limbs
All four limbs, long bones and proportions
Placenta & fluid
Placental position and amniotic fluid volume
Growth & wellbeing
Fetal measurements and cervical length screening
Understanding "soft markers"
Occasionally a report mentions a "soft marker" — a minor finding such as an echogenic bowel, a choroid plexus cyst, a slightly dilated kidney (pyelectasis), or a single umbilical artery. On their own, soft markers are not diagnoses and most babies with an isolated soft marker are entirely healthy.
Depending on the specific marker, your other screening results, and your individual risk factors, your obstetrician may suggest an additional test such as NIPT or a follow-up scan. This is a precautionary step, not a sign that something is definitely wrong.
Anomaly scan vs. NT scan
- NT scan (11–14 weeks) with double marker blood test screens chromosomal risk early
- Anomaly scan (18–22 weeks) is a full structural survey, not primarily a chromosomal screen
- The two together give a much fuller picture than either alone
If a concern is found
- Your radiologist will explain the finding clearly and without alarm
- A follow-up scan, fetal medicine consult, or further test may be advised
- Many findings turn out to be minor variants or resolve on rescan
What to expect at your appointment
- A full bladder is usually recommended — confirm timing when booking
- The scan takes 30 to 45 minutes and is done over the abdomen
- If the baby is in an awkward position, you may be asked to walk around and return
- Bring previous scan reports and your pregnancy file
- Under the PCPNDT Act, 1994, sex determination is not performed or disclosed under any circumstances
Common questions
When exactly should the anomaly scan be done?
FOGSI and ISUOG guidance recommends performing the anomaly scan between 18 and 22 weeks. Earlier, structures may be too small to assess reliably; later, the window for further evaluation narrows.
What does the anomaly scan actually check?
It systematically examines the brain, spine, face, heart, stomach, kidneys, bladder, abdominal wall and limbs, along with placenta position and amniotic fluid. Only what's documented in your report was assessed.
What is a soft marker on an anomaly scan?
A minor finding — like an echogenic bowel or choroid plexus cyst — that alone doesn't indicate a problem but may prompt your doctor to suggest additional testing depending on your overall risk profile.
Can the anomaly scan detect Down syndrome?
It can pick up some cases through associated markers, but first trimester combined screening (NT scan with double marker test) or NIPT are considerably more sensitive tools for this specific purpose.
Do I need a full bladder for the anomaly scan?
Yes, it's usually recommended as it helps visualise the lower uterus and pelvic structures more clearly. The scan typically takes 30 to 45 minutes.
"I have had all my pregnancy scans with Dr Nayana. She is the most professional, compassionate and amazing. She has all the patience to explain and answer my 100s of questions with a beautiful smile on her face. I highly recommend Nitara for all pregnancy scans."
"I went to Dr. Nayana for my pregnancy scans and I really like her. She is very kind and has good knowledge. She never hesitates to answer any questions, even small or silly ones. She explains everything very patiently."
Anomaly scan in HSR Layout, Bengaluru
Nitara Scans and Diagnostics offers the anomaly scan (TIFFA) and full second-trimester pregnancy imaging in HSR Layout, Bengaluru. Every scan is personally performed by Dr. Nayana N Sunku — DMRD, DNB Radiology, Fetal Medicine Fellow — with time for a clear explanation after the scan.