Pediatric Surgery
The paediatric domain tests congenital and acquired conditions that present with vomiting, obstruction or a mass in the neonate and infant. Marks come from pattern recognition and from knowing the age at which each lesion appears.
Neonates
- Bilious vomiting in a neonate is malrotation with midgut volvulus until proven otherwise: upper gastrointestinal contrast study and immediate laparotomy; do not wait.
- Hypertrophic pyloric stenosis: 3-6 weeks, non-bilious projectile vomiting, visible peristalsis, olive mass, hypochloraemic hypokalaemic metabolic alkalosis; correct with saline and potassium, then pyloromyotomy.
- Duodenal atresia: double bubble with no distal gas, associated with Down syndrome.
- Hirschsprung disease: meconium delayed beyond 48 hours, distension, transition zone on contrast enema, aganglionosis on rectal biopsy; treat with a levelling colostomy or primary pull-through.
- Omphalocele is covered by amnion and associated with chromosomal anomalies; gastroschisis lies to the right of the umbilicus with no sac, needing staged closure.
- Congenital diaphragmatic hernia: respiratory distress, scaphoid abdomen, bowel in the chest; intubate, pass a nasogastric tube, avoid bag-mask ventilation, repair after stabilisation.
- Necrotising enterocolitis: preterm infant, feeding intolerance, pneumatosis intestinalis; stop feeds, give antibiotics, operate for perforation.
- Biliary atresia: jaundice beyond two weeks with pale stools and direct hyperbilirubinaemia; Kasai portoenterostomy before 60 days.
Infants and children
- Intussusception: 6-18 months, colicky pain, redcurrant jelly stool, target sign on ultrasound; air enema reduction if stable.
- Inguinal hernia in an infant carries a high incarceration risk - repair promptly.
- Testicular torsion: acute scrotum, high-lying testis, absent cremasteric reflex - urgent exploration and bilateral fixation.
- Appendicitis is uncommon under three years and usually perforated at presentation.
Worked example
A three-week-old boy with projectile non-bilious vomiting and a palpable olive has chloride 88 mmol/L and bicarbonate 32 mmol/L. Reasoning: pyloric stenosis with metabolic alkalosis. Resuscitate with 0.9% saline plus potassium, wait for adequate urine output and correction of bicarbonate, then perform pyloromyotomy; anaesthesia on an uncorrected alkalosis risks postoperative apnoea.
Traps
- Giving an enema to a neonate with bilious vomiting.
- Confusing Hirschsprung disease with meconium plug syndrome.
- Repairing a congenital diaphragmatic hernia before pulmonary stabilisation.
- Forgetting that appendicitis in a toddler often presents as a perforation with a mass.