Okay, let's tackle this question about early postoperative complications of tracheostomy. The user wants a detailed explanation for a medical exam question, so I need to make sure I cover all the sections they specified.

First, the core concept. Tracheostomy complications are divided into early and late. Early complications usually occur within the first 48 hours. I should mention the main categories like bleeding, infection, and mechanical issues.

Next, the correct answer. The question is asking which option is NOT an early complication. Common early ones are hemorrhage, pneumothorax, subcutaneous emphysema, and infection. If the options include something like stenosis, which is a late complication, that's the answer. I need to explain why stenosis is late—due to granulation tissue or scarring over weeks.

For the wrong options, each one must be an early complication. Let's say the options are A: Hemorrhage, B: Pneumothorax, C: Stenosis, D: Subcutaneous emphysema. Then C is correct as the exception. I need to explain why each incorrect option is an early complication. Hemorrhage can be from vessel injury, pneumothorax from accidental puncture, subcutaneous from air leakage.

Clinical pearl: Remember the timeline—early vs. late. Stenosis is late. Maybe a mnemonic like "HAPPEN" for early complications? Not sure, but the key point is to distinguish early (within days) from late (weeks/months).

I need to check the character limit and make sure each section is concise. Use bold for key terms. Avoid markdown except for the required sections. Make sure the correct answer is clearly stated at the end.

**Core Concept**
Tracheostomy complications are classified as early (within 48 hours) or late (after 48 hours). Early complications include hemorrhage, pneumothorax, subcutaneous emphysema, and infection. Late complications like stenosis or granulation tissue formation develop due to prolonged tube presence or trauma.

**Why the Correct Answer is Right**
**Stenosis** is a **late** complication of tracheostomy, typically occurring weeks to months post-procedure. It results from fibrosis, granulation tissue overgrowth, or tracheal wall remodeling due to chronic irritation or malposition of the tracheostomy tube. Since the question asks for an **exception** to early complications, stenosis fits this criterion.

**Why Each Wrong Option is Incorrect**
**Option A: Hemorrhage** – Early hemorrhage occurs due to injury to thyroid or tracheal vessels during surgery.
**Option B: Pneumothorax** – Can result from accidental pleural injury during tracheostomy or tube displacement.
**Option D: Subcutaneous emphysema** – Air leakage into soft tissues is common in the immediate postoperative period.

**Clinical Pearl / High-Yield Fact**
Remember the "3 Ss" of early tracheostomy complications: **Bleeding, Subcutaneous emphysema, and Pneumothorax**. **Stenosis** is a red flag for **late** complications—always associate it with long-term tracheal remodeling.

**Correct Answer:

✓ Correct Answer: D. Tracheal stenosis