V6-10: Pyelocalyceal 3D model to facilitate access puncture in percutaneous nephrolithotomy
Percutaneous nephrolithotomy (PCNL) is the preferred treatment for kidney stones > 2 cm and lower pole stones > 1.5 cm. A critical step in PCNL is the safe puncture of the calyx to establish percutaneous access, while avoiding damage to abdominal viscera, pleura or large vessels. The urologist must mentally convert a two dimensional (2D) image obtained by fluoroscopy to a three dimensional (3D) image in order to perform a safe access to the calyx. The aim of this video is to demonstrate the use of a 3D pyelocalicial model that may facilitate safe punctures in PCNL.
We present a 71 year old male who was referred to our clinic because of 3 months of left renal colic pain. CT urography showed an incomplete left staghorn stone of 33 mm 690UH and an 11 mm 690UH stone in the inferior anterior calyx. We used the patient´s CT urography images to determine pyelocalicial anatomy and establish the size and exact location of the renal stones. We then developed a 3D model of the pyelocalicial system using biodegradable thermoplastic material. This was performed using InVesalius 3.0 and ReplicatorG / MakerWare software and a Bot Maker 3D printer. The printed model was then sterilized for use during the procedure. The model was positioned at a 2 cm distance from the skin to indicate the exact position and orientation of the calyx that we wanted to puncture.
We were able to puncture the inferior calyx on our first attempt, resulting in a clear urine output. A safety guide was installed followed by dilation of the tract up to 28Fr. Pneumatic intracorporeal lithotripsy was performed and fragments were extracted using a stone grasper. The patient was discharged on the second postoperative day after undergoing a non contrast CT that showed one residual stone fragment of 4 mm located in the inferior calyx.
The pyelocalicial 3D model allowed us to better determine the patient´s anatomy, as well as the exact location of the stone, thereby facilitating the safe puncture of the calyx. Hence, this 3D model could be used to treat complex kidney stones, for patients presenting anatomical abnormalities and by urologists learning how to do PCNL.