My 62-year-old mom has been dealing with pleural fluid buildup in her left lung for about 8 months now. We've done all sorts of tests, like bronchoscopy, pleural biopsy, ANA blot test, and checked for CEA and CA125 levels, and thankfully, both tuberculosis and malignancy have been ruled out. But now, the doctor has suggested Thoracoscopy. Can you explain what that is? Is it safe, and what should we expect from this procedure? She's a bit worried, and so am I. Any advice on how we should prepare or any questions we should ask her doctor about this?