What causes pelvocaliectasis of the kidney?

Many causes. Pelvicaliectasis of the kidney is dilation of the spaces in the kidney where urine goes prior to passage into the ureter (kidney tube) and bladder. This can indicate a possible obstruction downstream from the kidney (stone or congenital narrowing of the ureter) or possibly can be a normal anatomic variant. Talk to your doctor, especially if you have any pain, to determine appropriate testing.