Which one of the following is not a feature of congenital hyperophic pyloric stenosis
**Core Concept**
Congenital hypertrophic pyloric stenosis (CHPS) is a condition characterized by the thickening of the pyloric muscle, leading to gastric outlet obstruction in infants. This condition is often associated with a characteristic "olive" mass palpable on abdominal examination.
**Why the Correct Answer is Right**
The correct answer is related to the clinical presentation and pathophysiology of CHPS. The condition typically presents in the first few weeks of life, with symptoms such as projectile vomiting, dehydration, and weight loss. The thickened pyloric muscle leads to narrowing of the pyloric channel, causing gastric contents to be propelled through the stenotic area, resulting in the characteristic projectile vomiting.
**Why Each Wrong Option is Incorrect**
**Option A:** Projectile vomiting is a key feature of CHPS, so this option is incorrect.
**Option B:** The "olive" mass is a classic finding in CHPS, so this option is incorrect.
**Option C:** The condition often presents with non-bilious vomiting, so this option is incorrect.
**Clinical Pearl / High-Yield Fact**
A classic mnemonic to remember the key features of CHPS is "OLIVE": Olive mass, Loss of appetite, Vomiting (projectile), Ileus (not always present), Vomiting not bilious, and Erythema (of the abdomen).
**Correct Answer: C. Normal passage of bile**