Author: Maja Szymanska / Editor: Sarah Edwards / Codes: GC9, SLO2, SLO5 / Published: 17/05/2022

A 5-week-old boy is brought to the Emergency Department (ED) by his mother due to progressive post-feeding vomiting for the past 2 weeks. The baby is fully breast fed and has no past medical history. The mother describes that originally the baby would only vomit after some feeds, but now he vomits after every feed and the vomiting is forceful and projectile and has a white colour. She is worried that the baby appears lethargic and can no longer keep any milk down.

On general inspection, the child has dry mucous membranes.

You perform a test feed and notice a gastric peristaltic wave moving from left to the right across the abdomen.

On examination of the abdomen there is palpable “olive-shaped” mass in the right upper quadrant.

Basic observations are normal.

Blood tests show the following:

  • Na 131mmol/L
  • K 3.0 mmol/L
  • Cl 85 mmol/L
  • pH 7.54
  • pCO2 53 mmHg
  • pO2 61 mmHg
  • HCO3 45 mEq/L