All of the following are seen in chronic pyloric obstruction except: March 2010
## **Core Concept**
Chronic pyloric obstruction leads to gastric outlet obstruction, causing symptoms like persistent vomiting, dehydration, and electrolyte imbalances. The pathophysiology involves impaired gastric emptying, leading to gastric dilatation and complications such as metabolic alkalosis.
## **Why the Correct Answer is Right**
Metabolic acidosis is not typically seen in chronic pyloric obstruction. Instead, the condition often results in **metabolic alkalosis** due to the loss of gastric acid (HCl) through vomiting. The kidneys compensate for the alkalosis by retaining hydrogen ions and excreting bicarbonate. This process maintains the alkalotic state.
## **Why Each Wrong Option is Incorrect**
* **Option A:** Hypokalemia is seen due to the loss of potassium ions in the vomit and urine as the kidneys try to conserve sodium.
* **Option B:** Metabolic alkalosis occurs due to the loss of hydrogen ions from the stomach.
* **Option D:** Hyperchloremia is not typically observed; instead, hypochloremia occurs due to the loss of chloride ions in the gastric secretions.
## **Clinical Pearl / High-Yield Fact**
A key clinical correlation to remember is that chronic pyloric obstruction often presents with **vomiting**, which is **non-bilious** because the obstruction is proximal to the bile duct entry into the intestine. This characteristic helps differentiate it from other causes of gastric obstruction.
## **Correct Answer:** D. Metabolic acidosis