Final answer:
Nephrostomy is the temporary diversion of urinary drainage using an external catheter that drains the renal pelvis.
Step-by-step explanation:
The temporary diversion of urinary drainage by means of an external catheter that drains the renal pelvis is called nephrostomy. This procedure involves creating a small opening in the skin and inserting a catheter directly into the renal pelvis to allow urine to drain out of the kidney. It is commonly used when there is a blockage in the urinary system or after surgery.