Pediatric Gastroenterology, Hepatology and Nutrition
This domain tests nutritional assessment and rehabilitation, the surgical causes of neonatal and infant vomiting, acute and persistent diarrhoea, and cholestatic liver disease. Questions tend to be sequential: recognise the pattern, choose the first investigation, then choose the first management step.
Nutrition
- Exclusive breastfeeding for six months, then complementary feeding with iron-rich foods. Continue breastfeeding to 2 years.
- Severe acute malnutrition: weight-for-height z-score below -3, mid-upper-arm circumference under 115 mm, or bilateral pitting oedema. Stabilise with F-75, then rehabilitate with F-100; give vitamin A, zinc and broad-spectrum antibiotics. Avoid refeeding syndrome and do not give iron during stabilisation.
Vomiting in infancy
- Pyloric stenosis: 3-6 weeks, projectile non-bilious vomiting, hypochloraemic hypokalaemic metabolic alkalosis, olive-shaped mass, confirmed on ultrasound. Correct the electrolytes before pyloromyotomy.
- Bilious vomiting in a neonate means malrotation with volvulus until excluded; it is a surgical emergency.
- Gastro-oesophageal reflux is physiological in a thriving infant; alarm features (bilious or bloody vomiting, failure to thrive, apnoea) require investigation.
Diarrhoea
- Use low-osmolarity oral rehydration salts plus zinc 10-20 mg/day for 10-14 days, and continue feeding throughout.
- Intussusception: 6-18 months, colicky pain, red-currant jelly stool, target sign on ultrasound, treated with air enema if there is no peritonitis.
Liver disease
- Conjugated jaundice persisting beyond two weeks is always pathological. Causes include biliary atresia (Kasai portoenterostomy before 60 days), neonatal hepatitis, metabolic disease and sepsis.
- Prevent hepatitis B vertical transmission with vaccine plus immunoglobulin within 12 hours of birth.
Coeliac disease
Screen with tissue transglutaminase IgA together with a total IgA level, then confirm with duodenal biopsy. HLA-DQ2/DQ8 negativity excludes coeliac disease.
Worked example
A 4-week-old boy has projectile vomiting after feeds. Venous gas shows pH 7.52, chloride 88 mmol/L, potassium 3.1 mmol/L and bicarbonate 34 mmol/L. This is pyloric stenosis with a hypochloraemic hypokalaemic metabolic alkalosis. Give normal saline with added potassium chloride, correct the chloride and potassium, and only then proceed to pyloromyotomy; operating on an alkalotic infant risks postoperative apnoea.
Traps
Giving iron during stabilisation of severe malnutrition, ordering a barium study before correcting electrolytes, and missing biliary atresia because jaundice was labelled physiological.