## **Core Concept**
The patient's presentation suggests a complication of otitis media, specifically **mastoiditis**, which is an infection of the mastoid part of the temporal bone. This condition can arise from the spread of infection from the middle ear, especially in the context of chronic otitis media. The symptoms described, such as fever, unilateral post-auricular pain, mastoid bulging, and displacement of the pinna, are classic for mastoiditis.

## **Why the Correct Answer is Right**
The correct answer involves surgical intervention, specifically **mastoidectomy**. This procedure is indicated in cases of acute mastoiditis with significant complications, such as coalescent mastoiditis where there is destruction of the bony trabeculae between mastoid air cells. The presence of chronic persistent pus discharge from the same ear, along with the acute presentation of mastoiditis, signifies the need for surgical intervention to drain the infection and prevent further complications. Mastoidectomy helps in removing the infected mastoid air cells, thereby controlling the infection.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option might suggest a conservative approach with antibiotics, which is not sufficient in this case given the presence of complications like loss of bony trabeculae and chronic discharge. Antibiotics alone may not adequately address the localized infection and its complications.
- **Option B:** This option could imply a less invasive procedure or a different treatment approach, which might not directly address the need for drainage and removal of infected tissue as required in this scenario.
- **Option C:** This could potentially be a different surgical or medical treatment that does not directly address the acute need for mastoidectomy in the context provided.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that **coalescent mastoiditis**, suggested by the loss of bony trabeculae, represents a serious complication of otitis media that requires prompt surgical intervention, typically mastoidectomy, to prevent further complications such as intracranial infections.

## **Correct Answer:** . Mastoidectomy.