Anomaly Scan — Every Organ System That Gets Checked

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.