All are false except one in case of hypertrophic pyloric stenosis –
**Core Concept**
Hypertrophic pyloric stenosis (HPS) is a congenital condition characterized by the thickening of the pyloric muscle, leading to gastric outflow obstruction. The pathophysiology involves the pyloric sphincter's failure to relax, causing a functional obstruction.
**Why the Correct Answer is Right**
The correct mechanism in HPS is the hypertrophy of the pyloric muscle, which is due to an increase in the number of smooth muscle cells and the deposition of collagen. This leads to the narrowing of the pyloric channel, causing gastric outflow obstruction. The pyloric sphincter's failure to relax is due to the hypertrophied muscle, which is unresponsive to normal inhibitory stimuli.
**Why Each Wrong Option is Incorrect**
**Option A:** This statement is incorrect because it does not accurately describe the pathophysiology of HPS. The condition is not primarily due to an increase in the pyloric mucosa.
**Option B:** This statement is incorrect because it does not account for the functional obstruction caused by the hypertrophied pyloric muscle. The pyloric sphincter's failure to relax is a key feature of HPS.
**Option C:** This statement is incorrect because it does not accurately describe the primary cause of HPS. The condition is not primarily due to an increase in the pyloric mucosa or the pyloric gland.
**Clinical Pearl / High-Yield Fact**
The "olive" sign, a palpable mass in the right upper quadrant, is a classic clinical finding in HPS. This sign is due to the hypertrophied pyloric muscle, which can be felt as a firm, mobile mass.
**Correct Answer:** C. This statement is correct because it accurately describes the pathophysiology of HPS.