**Core Concept**
The clinical presentation suggests a condition affecting the hip in a pediatric patient, with key features including abrupt onset of pain, hip held in abduction, and elevated ESR. This scenario is indicative of **transient synovitis** or **septic arthritis**, both of which require prompt diagnosis and management.

**Why the Correct Answer is Right**
Given the acute presentation and elevated ESR, it's crucial to differentiate between transient synovitis and septic arthritis. The next step involves imaging and possibly aspiration to guide further management.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because immediate surgery is not typically the first step without confirming the diagnosis.
**Option B:** Incorrect as it might not be the immediate next step without further diagnostic workup.
**Option C:** Incorrect because, although it might be part of the management, it's not specified as the next line of management without more context.

**Why Each Wrong Option is Incorrect (continued)**
**Option D:** This option is not provided, so we proceed to the correct answer.

**Clinical Pearl / High-Yield Fact**
In pediatric patients presenting with acute hip pain, it's essential to consider septic arthritis due to its potential for rapid joint destruction. Prompt recognition and intervention are critical.

**Correct Answer:** D. Ultrasound guided aspiration of the hip.