Congenital anomalies and dysmorphic newborn assessment — formative SAQs

SAQ 1 (10 marks)

A term newborn is noted to be hypotonic with a flat facial profile, upslanting palpebral fissures, and a single palmar crease. On day two the baby begins to vomit green fluid. ^[3]

1. What is the most likely syndromic diagnosis, and which chromosomal abnormality underlies it? (2) ^[3]
2. Outline the immediate management of the bilious vomiting. (4) ^[3]
3. List four associated conditions this baby must be screened for during the neonatal period. (4) ^[3]

Model answer

1. The clinical picture is Down syndrome (Trisomy 21). The flat facial profile, upslanting palpebral fissures, hypotonia, and single palmar crease form the recognisable pattern; the underlying cause is a third copy of chromosome 21, usually from non-disjunction. ^[3]

2. Bilious (green) vomiting in a newborn is a surgical emergency. Make the baby nil-by-mouth, pass a nasogastric tube on free drainage, establish intravenous access, and correct fluid and electrolyte losses. In Trisomy 21 the classic cause is duodenal atresia (the "double bubble" on an abdominal X-ray), so obtain urgent imaging and refer to paediatric surgery. ^[3]

3. Four conditions to screen for: an atrioventricular septal defect or other congenital heart disease (echocardiogram on every baby), congenital hypothyroidism, congenital hearing loss (hearing screen), and duodenal or gastrointestinal atresia. Ongoing surveillance also covers developmental delay and atlanto-axial instability later in childhood. ^[3]