**Core Concept:**
The T-tube, also known as choledochojejunostomy tube, is a temporary drainage tube placed during cholecystectomy (gallbladder surgery) to relieve bile duct obstruction and monitor bile leak. The tube is usually removed when the patient shows clinical improvement, bilirubin levels decrease, and cholangiogram confirms patency and absence of leak.

**Why the Correct Answer is Right:**
The T-tube is usually removed on the 5th to 10th postoperative day (POD) after the surgery. This time frame allows adequate healing of the biliary tract anastomosis, resolution of inflammation, and sufficient time for bilirubin levels to decrease. Additionally, a cholangiogram is performed on the 7th to 10th POD to confirm patency and absence of bile leak. If these criteria are met, the T-tube can be safely removed.

**Why Each Wrong Option is Incorrect:**
A. Removing the T-tube too early on the 3rd POD might lead to bile leak, cholangitis, and potential biliary stricture formation.
B. Removing the T-tube on the 15th POD is too late, increasing the risk of anastomotic stricture and patient discomfort.
C. The T-tube may be removed once the bilirubin levels start to decrease, but this is not a universally applicable criterion as bilirubin levels can decrease due to other causes.
D. The T-tube is usually removed when the patient is fully recovered, which is an imprecise criterion, as recovery can be influenced by various factors unrelated to the T-tube removal.

**Clinical Pearl:**
The optimal timing for T-tube removal depends on clinical improvement, resolution of inflammation, and confirmation of bile duct patency and absence of bile leak on cholangiogram. This ensures successful healing of the anastomosis and minimizes complications related to T-tube retention.

**Correct Answer:**
D. The T-tube is usually removed when the patient is fully recovered.

**Explanation:**
The correct answer is D because the decision to remove the T-tube is primarily based on assessing the patient's overall improvement and stability rather than on specific laboratory values or radiological findings. Patient recovery is a composite of clinical improvement, resolution of inflammation, and confirmation of bile duct patency and absence of bile leak on cholangiogram. This ensures that the T-tube has served its purpose effectively and minimizes complications associated with continued T-tube retention.