For people who have kidney problems that prevent urine from passing into the bladder, the pressure and discomfort can be difficult to bear and the health risks can be serious. A nephrostomy tube is a small catheter that is inserted into the kidney through the flank to release urine into a bag. Your MIT radiologist will first apply a local numbing agent to eliminate pain. Most patients report feeling only pressure during the procedure. Your MIT doctor will use ultrasound or fluoroscopy (specialized x-ray) imaging to guide a very small, flexible tube into the kidney and secure the exiting end against the skin, where it will remain out of your way. Quick outpatient follow-up is done every 6-8 weeks to ensure the tube is draining adequately and to replace it with a fresh line.