## Core Concept
The immediate postoperative period is crucial for monitoring electrolyte imbalances due to various factors such as fluid shifts, anesthetic effects, and surgical stress. Common electrolyte abnormalities during this period include hyponatremia, hyperkalemia, hypokalemia, and hypocalcemia. Understanding the typical electrolyte disturbances helps in identifying the exception.

## Why the Correct Answer is Right
Hypocalcemia (Option D) is indeed a common electrolyte abnormality in the immediate postoperative period, especially after surgeries involving blood transfusions or manipulation of tissues that could lead to citrate toxicity or release of inflammatory mediators. On the other hand, **hypercalcemia** is less commonly associated with the immediate postoperative period as an expected or typical abnormality compared to the others listed. The stress of surgery and fluid shifts more commonly lead to decreases or imbalances in sodium, potassium, and calcium levels rather than an increase in calcium.

## Why Each Wrong Option is Incorrect
* **Option A (Hyponatremia):** This is a common electrolyte abnormality in the postoperative period due to fluid shifts, syndrome of inappropriate antidiuretic hormone secretion (SIADH), or administration of hypotonic fluids.
* **Option B (Hyperkalemia):** This can occur due to tissue damage, blood transfusions, and renal insufficiency, making it a plausible electrolyte abnormality postoperatively.
* **Option C (Hypokalemia):** This can result from the use of diuretics, certain anesthetic agents, and the stress response leading to increased potassium excretion.

## Clinical Pearl / High-Yield Fact
A key point to remember is that **hypocalcemia** is often seen in the postoperative period, particularly after massive blood transfusions or surgeries involving significant tissue trauma. Conversely, **hypercalcemia** is not typically an immediate postoperative complication unless there is a specific underlying condition or complication.

## Correct Answer: B. Hypercalcemia