Percutaneous nephrolithotomy (PCNL) is a minimally-invasive procedure to remove stones from the kidney by a small puncture wound (up to about 1 cm) through the skin.
If the ureteric catheter is placed in the upper pole of the kidney, it should be pulled down so that the tip is inside the renal pelvis.
Fluoroscopy monitoring should be continuous so that the sequence of calyces be filled can help to identify the position of posterior calyx.
[1] With a small 1 centimeter incision in the loin, the percutaneous nephrolithotomy (PCN) needle is passed into the pelvis of the kidney.
A 'retrograde' technique has recently been updated wherein a thin wire is passed from inside the kidney to outside the flank with the aid of a flexible ureteroscope.