The ultrasound image shows a classic longitudinal view of a markedly thickened pyloric muscle with an elongated pyloric channel. This finding is consistent with hypertrophic pyloric stenosis (HPS), a condition most commonly seen in male infants between 2 and 8 weeks of age.

The most characteristic clinical finding associated with HPS is an “olive-shaped” palpable mass in the right upper quadrant or epigastric region, which represents the hypertrophied pylorus.

Clinical presentation of HPS includes:

Non-bilious projectile vomiting (due to gastric outlet obstruction)

Dehydration and weight loss

A palpable “olive” mass on physical exam

Visible peristalsis may be noted on the abdominal wall

Sonographic diagnostic criteria for HPS:

Pyloric muscle thickness ≥ 3 mm

Pyloric channel length ≥ 15–17 mm

“Cervix sign” or “target sign” (transverse view)

Failure of gastric contents to pass through the pylorus on real-time imaging

Differentiation from other options:

B. Fever of unknown origin: Not characteristic of HPS.

C. Red currant jelly stools: Classic for intussusception.

D. Bilious vomiting: Seen in distal duodenal or jejunal obstruction, not in pyloric stenosis (vomiting is non-bilious in HPS).