Coagulum pyelolithotomy.

Stones in the kidney can be a source of both challenge and frustration to the surgeon. A stone seemingly easily accessible at the start of surgery can move into the depths of a renal calix during the procedure. The intraoperative injection of certain coagulation factors into the renal pelvis will produce a gelled substance (coagulum), which can encase the free-lying stones within the collecting system, thereby expediting their removal.