Percutaneous (through the skin) urinary procedures help drain urine from your bladder and get rid of kidney stones. A percutaneous nephrostomy is the placement of a small, flexible rubber tube (catheter) through your skin into your kidney to drain your urine. It is inserted through your back or flank. Percutaneous nephrostolithotomy (or nephrolithotomy) is the passing of a special medical instrument through your skin into your kidney. This is done to remove kidney stones.