**Core Concept**
Pseudoaneurysm, also known as a false aneurysm, is a leakage of arterial blood from the arterial wall into the surrounding tissue, which is contained by a semi-permeable membrane. This condition often results from trauma, infection, or iatrogenic causes, such as invasive medical procedures.

**Why the Correct Answer is Right**
The treatment of pseudoaneurysm typically involves repairing the damaged arterial wall to prevent further blood leakage. This can be achieved through various methods, including:

* **Option C: Ultrasound-guided thrombin injection**: This minimally invasive procedure involves injecting thrombin into the pseudoaneurysm under ultrasound guidance to promote clot formation and seal the arterial defect.
* **Option D: Surgical repair**: Open surgery may be necessary to repair the damaged arterial wall, especially in cases where the pseudoaneurysm is large or located in a critical area.

**Why Each Wrong Option is Incorrect**
* **Option A:** Antiplatelet therapy is not a primary treatment modality for pseudoaneurysm, although it may be used as an adjunctive measure to prevent further clot formation.
* **Option B:** Antibiotics are not a primary treatment modality for pseudoaneurysm, unless the condition is caused by an infectious agent.

**Clinical Pearl / High-Yield Fact**
When treating a pseudoaneurysm, it is essential to identify and address the underlying cause, whether it be trauma, infection, or iatrogenic injury. Early intervention can help prevent complications and reduce the risk of rupture.

**Correct Answer: C, D. Ultrasound-guided thrombin injection and Surgical repair.**