How long is swelling in the abdomen and back expected to last after a perc kidney stone remova surgery? Tenderness?

Not long. There should be minimal, if any abdominal swelling after percutaneous kidney stone removal. Unless either the peritoneum was punctured or a large volume of irrigating fluid escaped into the retroperitoneum. In which case subject might develop temporary ileus, meaning that bowel stops working and abdomen swells. Flank swelling and pain should settle down after 3-4 days.