A 43-year-old woman undergoes open cholecystectomy. Intraoperative cholangiogram revealed multiple stones in the CBD. Exploration of the CBD was performed to extract gallstones. The CBD was drained with a T-tube. After 10 days, a T-tube cholangiogram reveals a retained CBD stone. This should be treated by which of the following?
Laparotomy and CBD exploration Subcutaneous heparinization Antibiotic therapy for 6 months and then reevaluation Extraction of the stone through the pathway created by the T-tube (after 6 weeks)