Imagine that you undergo surgery, and then a follow-up exam reveals that your doctors left a little something behind—some gauze, a tool or other totally foreign object.

Each year, there are up to 2,000 cases of retained surgical items (RSIs) left inside U.S. patients, according to Nothing Left Behind, a national surgical patient safety project that helps prevent these potentially serious medical errors. These costly mistakes can put patients at risk of unnecessary pain, expensive follow-up procedures and, in the most extreme cases, even death.

But thankfully, medical staffs have help. Hospitals can employ groups such as Nothing Left Behind to help prevent RSIs. These organizations use manual and computerized programs to account for every sponge, tool and any other item used during surgery. If the numbers don’t add up, some programs even alert operating room teams before they close up their patients, averting potential errors.

But patients can also be proactive. Before you agree to a procedure, make sure to look into the hospital’s RSI events, suggests Tracy Pfeifer, MD, a plastic surgeon in New York City. For starters, log onto and search under “patient safety indicators.” And talk with your doctor about what hospital programs are in place to ensure your safety both during and after surgery.