## **Core Concept**
Ureterosigmoidostomy is a surgical procedure that involves implanting the ureters into the sigmoid colon. This procedure can lead to electrolyte imbalances due to the absorption of substances from the urine by the colonic mucosa.

## **Why the Correct Answer is Right**
The correct answer, **Hyperchloremic metabolic acidosis**, occurs because the colonic mucosa absorbs chloride ions in exchange for bicarbonate ions. This leads to a decrease in bicarbonate levels (metabolic acidosis) and an increase in chloride levels (hyperchloremia). The mechanism involves the diffusion of ammonia (NH3) and carbon dioxide (CO2) into the colonic lumen, where they form ammonium (NH4+) and bicarbonate (HCO3-). However, the colonic mucosa absorbs chloride ions (Cl-) in exchange for bicarbonate ions, leading to bicarbonate loss and chloride gain.

## **Why Each Wrong Option is Incorrect**
- **Option A:** Hypokalemia can occur due to various reasons but is not the most directly related electrolyte abnormality to ureterosigmoidostomy compared to acid-base disturbances.
- **Option B:** Hypocalcemia is not directly related to the electrolyte disturbances typically seen with ureterosigmoidostomy.
- **Option C:** While changes in potassium levels can occur, **Hypokalemia** is not the characteristic electrolyte abnormality associated with this procedure.

## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that patients undergoing ureterosigmoidostomy are at risk of developing **hyperchloremic metabolic acidosis**, also known as chloride acidosis or renal tubular acidosis type 2. This condition requires monitoring and sometimes management with alkali therapy to mitigate its effects.

## **Correct Answer:** . Hyperchloremic metabolic acidosis