**Core Concept**
In the context of common bile duct (CBD) surgery, a small leak is a recognized complication that requires prompt and effective management. The underlying principle is to minimize the risk of infection, peritonitis, and long-term sequelae while allowing for optimal healing and resolution of the leak.

**Why the Correct Answer is Right**
The best approach to managing a small CBD leak after surgery is endoscopic retrograde cholangiopancreatography (ERCP) with stent placement. This minimally invasive procedure allows for direct visualization of the bile ducts and precise placement of a stent to facilitate drainage and promote healing. The stent helps to prevent bile from accumulating and causing further damage to the surrounding tissues. Additionally, ERCP with stent placement can be performed under conscious sedation, reducing the risk of complications associated with more invasive surgical procedures.

**Why Each Wrong Option is Incorrect**
* **Option A:** Surgical exploration and repair is typically reserved for larger leaks or those that are refractory to endoscopic management, as it carries a higher risk of complications and longer recovery times.
* **Option B:** Conservative management with antibiotics and supportive care alone may not be sufficient to manage a small CBD leak, as it can lead to prolonged illness and potentially life-threatening complications.
* **Option C:** Percutaneous transhepatic biliary drainage (PTBD) may be considered in certain cases, but it is generally reserved for larger leaks or those that are not amenable to ERCP.

**Clinical Pearl / High-Yield Fact**
When managing a small CBD leak after surgery, it is essential to monitor the patient closely for signs of infection or peritonitis, such as fever, abdominal pain, or leukocytosis. Early recognition and prompt treatment can significantly improve outcomes and reduce the risk of long-term complications.

**Correct Answer: B. ERCP with stent placement. ERCP with stent placement**