Concerning infantile hypertrophic pyloric stenosis, the following statements are correct:

• A. False: The vomiting is non-bilious because the obstruction lies proximal to the bile duct opening.
• B. True
• C. False: Onset is typically 2-8 weeks of age, not the first 24 hours.
• D. False: The vomiting is projectile but NON-bilious; bile-stained vomiting points to a more distal obstruction.
• E. True

Infantile hypertrophic pyloric stenosis (IHPS)

IHPS is progressive hypertrophy of the circular pyloric muscle causing gastric outlet obstruction in early infancy.

Key epidemiology and presentation

• Onset 2-8 weeks, rarely after 13 weeks; boys:girls about 4:1; commoner in first-borns; family history in about 20%.
• Vomiting is non-bilious (the obstruction is proximal to the bile duct), projectile, and occurs immediately after feeds.
• The baby remains hungry until dehydration supervenes; weight loss and small green starvation stools occur.
• Mild unconjugated jaundice (icteropyloric syndrome) may be seen.

Examination and confirmation

• Test feed: visible gastric peristalsis (left to right) and a palpable olive-shaped mass in the RUQ at the lateral border of the rectus.
• Ultrasound confirms the diagnosis; ABG shows hypochloraemic hypokalaemic metabolic alkalosis.

Management

Resuscitate with N/2 saline plus KCl (avoid Hartmann's), correct the alkalosis, then Ramstedt's pyloromyotomy.

Statement-by-statement verdict

Why A is false

The vomiting is non-bilious because the obstruction is proximal to the ampulla.

Why B is true

Boys are affected about four times as often as girls.

Why C is false

Onset is typically 2-8 weeks, rarely after 13 weeks, not in the first 24 hours.

Why D is false

The vomiting is projectile but non-bilious; bilious vomiting indicates a more distal obstruction.

Why E is true

Ultrasound is the confirmatory investigation.