Anomaly Scan — Every Organ System That Gets Checked
In short
The anomaly scan examines the baby’s brain, face, spine, heart, chest, abdominal organs, kidneys, bladder and limbs, along with the placenta, cord and amniotic fluid. It is a structural survey, not a test of function or intelligence, and it cannot detect every condition. Fetal sex is neither determined nor disclosed, as per the PC-PNDT Act.
The anomaly scan at 18–22 weeks is the most detailed structural ultrasound of pregnancy. This page covers exactly what is examined, what the report means, and what happens when findings are seen.
1. When and where
Performed at 18–22 weeks, optimally 20–22 weeks for clearest visualisation. Done by ISUOG-trained sonographers or fetal medicine specialists. Comprehensive structural assessment of the fetus. Typically 30–60 minutes; longer if visualisation difficult or if anomaly suspected requiring detailed evaluation.
2. Brain and central nervous system
Cerebral hemispheres, ventricles, midline structures, cerebellum, cisterna magna, posterior fossa, spine throughout its length. Looking for: ventriculomegaly, neural tube defects (spina bifida, encephalocele), cerebellar abnormalities, brain malformations.
3. Face and neck
Facial profile, orbits, nose, lips, palate. Cleft lip and palate identified. Nuchal fold thickness (different from NT). Looking for: cleft lip/palate, micrognathia, facial anomalies suggestive of syndromes.
4. Heart
Four-chamber view, three-vessel view, outflow tracts (aorta and pulmonary artery), aortic arch. Heart rate and rhythm. Looking for: structural cardiac defects, septal defects, hypoplastic chambers, valve abnormalities, abnormal vessel positioning. Detailed fetal echocardiography may be added in high-risk pregnancies.
5. Chest, lungs and diaphragm
Lung appearance (echogenicity, position), diaphragm continuity, presence of any masses or effusions. Looking for: diaphragmatic hernia, lung lesions, pleural effusions.
6. Abdomen, stomach, kidneys, bladder, bowel
Stomach (presence, position), kidneys (size, location, internal architecture), bladder (size, content), abdominal wall integrity at cord insertion. Looking for: renal anomalies, urinary obstruction, abdominal wall defects (gastroschisis, omphalocele), bowel obstruction.
7. Limbs and extremities
All four limbs visualised, femur, tibia, fibula, foot; humerus, radius, ulna, hand. Limb lengths measured. Hands and feet position. Looking for: limb reduction defects, skeletal dysplasia, talipes, polydactyly.
8. Placenta, cord and amniotic fluid
Placental position, structure and appearance. Umbilical cord (3 vessels). Amniotic fluid volume. Looking for: placenta previa, abnormal placentation, single umbilical artery, oligohydramnios or polyhydramnios.
Frequently Asked Questions
When is the anomaly scan done?
How long does the scan take?
Can all anomalies be detected?
What happens if anomalies are found?
Should I have a 4D scan as well?
Will the scan tell us the sex of the baby?
Is the scan safe for the baby?
What if my baby is in a difficult position?
Medically reviewed by Dr. Priyadatt Patel, MBBS, MS — Senior Gynecologist, Advanced Laparoscopic Surgeon, IVF and Endometriosis Programme Lead. Last reviewed 27 August 2026.
This page is for education and does not replace individual medical advice. Every pregnancy is different and outcomes vary. Please discuss your own circumstances in consultation.
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