FIG. 2.

The longitudinal approach to renal access. (a) Anatomical landmarks used for percutaneous nephrolithotomy in the prone position. (P marks the paraspinous muscle, I the iliac crest, and R the 12th rib). (b) Image demonstrates a common placement for the ultrasound probe (yellow rectangle) oriented along the longitudinal axis of the kidney. In this illustration, the probe is placed below the 12th rib and must be tilted cephalad to image the kidney. In some cases, placing the probe above the 12th rib or higher may be necessary to achieve appropriate renal access. Two potential sites of needle entrance are marked with the yellow dots. (c) Schematic drawing of the coronal and axial views of the needle approach with the ultrasound probe positioned along the longitudinal axis of the kidney. A needle (represented by the black lines) can be inserted into a posterior calix of choice with the path of insertion in full view of the imaging plane. (d) Intraoperative image of a needle puncture through the lower pole. The nondominant hand holds the ultrasound probe, while the dominant hand holds the needle. (e) Intraoperative image of a needle puncture through the upper pole. (f) Ultrasonographic image of the kidney along its longitudinal axis demonstrating that the needle (white arrow) can be imaged along its entire insertion path as it enters the renal calix.