What are the key clinical signs and symptoms of hypertrophic pyloric stenosis that I should look for in infants?

When assessing infants with persistent vomiting, while gastro-oesophageal reflux disease (GORD) is a common consideration NICE NG1, NICE CKS, it is crucial to also evaluate for hypertrophic pyloric stenosis (HPS), which presents with distinct clinical signs and symptoms.

• The most characteristic symptom of HPS is projectile, non-bilious vomiting, which typically occurs after feeds and becomes progressively more forceful Deluca 1993, Hernanz-Schulman 2003. This vomiting is usually not stained with bile Deluca 1993.


• Symptoms commonly begin between 2 and 8 weeks of age, although onset can vary Deluca 1993, Hernanz-Schulman 2003.


• Infants with HPS often exhibit weight loss or failure to thrive due to the persistent inability to retain nutrients Deluca 1993.


• Signs of dehydration may also be present as a result of significant fluid loss from vomiting Deluca 1993.


• On physical examination, visible gastric peristalsis may be observed as waves of contraction moving across the upper abdomen from left to right, particularly after a feed Deluca 1993.


• A crucial diagnostic sign is the presence of a palpable "olive" mass in the epigastrium or right upper quadrant during abdominal examination Deluca 1993, Hernanz-Schulman 2003. This firm, mobile mass represents the hypertrophied pylorus Deluca 1993.


• Despite frequent vomiting, infants with HPS often remain hungry, indicating an obstructive issue rather than a lack of appetite Deluca 1993.