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Pyloric stenosis — DCH MCQ

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HardNeonatologyPyloric stenosisDCH

A 7-week-old boy has an 8-day history of increasingly forceful vomiting shortly after feeds. The vomit is not bile-stained and the episodes are not consistently projectile. He immediately seeks another feed. He has no fever or diarrhoea, has crossed down two weight centile spaces and is passing fewer wet nappies. His abdomen is soft and no mass is palpable. Venous blood results are: pH 7.51, bicarbonate 36 mmol/L, chloride 87 mmol/L and potassium 3.2 mmol/L. What is the most likely diagnosis?

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Correct answer: D — Hypertrophic pyloric stenosis

The diagnosis is hypertrophic pyloric stenosis. In an infant younger than 2 months, progressive non-bilious post-feed vomiting, immediate hunger, faltering weight and dehydration indicate gastric outlet obstruction at the pylorus. Loss of gastric hydrochloric acid produces hypochloraemic, often hypokalaemic, metabolic alkalosis. Failure to palpate a pyloric “olive” does not exclude the diagnosis. Gastro-oesophageal reflux usually causes effortless regurgitation without marked dehydration or electrolyte disturbance. Viral gastroenteritis commonly includes diarrhoea or systemic symptoms and may produce metabolic acidosis. Cow's milk protein allergy is more often associated with eczema, feeding distress, diarrhoea or blood and mucus in the stool. Malrotation with volvulus classically causes bile-stained green vomiting and may cause acute deterioration. NICE recommends same-day specialist assessment for infants younger than 2 months with progressively worsening or forceful vomiting.

Reference: National Institute for Health and Care Excellence. Gastro-oesophageal reflux disease in children and young people: diagnosis and management, NG1, recommendations 1.1.5 and 1.1.19. 2015, updated 2019. https://www.nice.org.uk/guidance/ng1/chapter/Recommendations