It is currently estimated that 1.5%-2% of cancers diagnosed in the United States are the result of medical ionizing radiation.¹ In addition to cancer, medical personnel with occupational radiation exposure have an increased risk of cardiovascular disease, cataracts, and inflammatory diseases including arthritis.^2-4 Subsequently, it is important to reduce radiation exposure to patients and medical staff in accordance with the principles of ALARA (as low as reasonably achievable).

In a semi-live surgery presented at the 2023 AUA annual meeting, a hybrid percutaneous nephrolithotomy (PCNL) technique was demonstrated in a 60-year-old cirrhotic patient with a large renal pelvic and lower-pole stone burden. In this technique which combines ultrasound, low-dose fluoroscopy, endoscopic combined intrarenal surgery (ECIRS), and laser guidance, fluoroscopy time was dramatically reduced. In this recap, we summarize 10 steps that facilitated this high-risk, complicated PCNL.

1. Rely on tactile feedback for guidewire and ureteroscope insertion. First, the patient was placed in the prone split-leg position to allow flexible cystoscopy. By using a flexible cystoscope, an angle-tipped hydrophilic glidewire was inserted into the ureter and up to the kidney relying only on the surgeon’s tactile feedback, without fluoroscopy (Figure 1, A). The wire passed smoothly along the ureter and an abrupt stop indicated the wire had contacted the stone, while a gentler, more bouncy resistance indicated the wire was correctly positioned in the upper pole. Using a marking pen, the external end of the wire was indicated on the drape (Figure 1, B). The glidewire was then switched for a double-floppy superstiff guidewire using a 5F open-ended catheter. A dual-lumen catheter was used to position a standard safety wire (Figure 1, C). Over the superstiff guidewire a fiber-optic flexible ureteroscope was inserted using tactile feedback and then passed up into the kidney using direct vision.

2. Use ultrasound to assess renal depth and delineate a safe zone. The depth of the kidney collecting system from the skin was assessed to select the appropriate needle length. In addition, ultrasound helped identify a posterior calyx by gentle deflection of the ureteroscope tip (Figure 2, A). Surrounding viscera including the spleen (Figure 2, B), the inferior pleural margin (Figure 2, C), and the bowel were identified and a safe zone was marked on the skin (Figure 2, D).

3. Use fluoroscopy only when necessary and in accordance with the ALARA principle. The fluoroscopy was first changed from automatic exposure control (30 pulses per second) to pulsed fluoroscopy at 1 pulse-per-second. The low-dose button was also depressed (Figure 3). The combination of these 2 changes reduces radiation dose by >90%. Saved images instead of live fluoroscopy were used to provide anatomical information.

4. Perform low-dose retrograde pyelogram. Although fluoro-less PCNL is possible, a retrograde pyelogram can clarify renal anatomy in a way not possible using ultrasound alone. In this case, based on ultrasound and direct vision, the upper pole appeared to be an ideal access. However, the retrograde pyelogram demonstrated a bifid collecting system with a narrow infundibulum (Figure 4). Subsequently, we needed an alternate access.

5. Employ ECIRS to improve safety and simplify access. Using the ureteroscope, a posterior upper midpole calyx with a wide and short infundibulum was identified (Figure 5, A). Injection of air confirmed this was a posterior calyx (Figure 5, B). The ureteroscope tip was placed touching the papilla to allow for subsequent needle targeting.

6. Use the laser pointer on the C-arm image intensifier to guide needle insertion. With the ureteroscope tip in the desired calyx, a Kelly clamp was aligned using a few taps of pulsed fluoroscopy. The tip of the Kelly clamp was positioned directly over the tip of the ureteroscope and the laser was aligned with the tip of the clamp (Figure 6, A). This allowed the surgeon to maintain alignment while inserting the needle (Figure 6, B) with only a couple of taps of pulsed fluoroscopy (Figure 6, C). This technique is called the “Laser Direct Alignment Radiation Reduction Technique (DARRT)”.

7. Utilize ECIRS for direct vision during needle insertion, course correction, balloon dilation, and sheath insertion. Having a ureteroscope in place in the kidney allowed direct visualization of needle insertion. In this case, the needle was in the collecting system, but was positioned in the infundibulum (Figure 7, A). Under direct vision, without additional fluoroscopy, the needle was repositioned to a papillary puncture (Figure 7, B). Through-and-through access was obtained (Figure 7, C), and tract dilation and sheath insertion were performed under direct vision (Figure 7, D). This removes the uncertainty of purely fluoroscopic or ultrasonic approaches and improves the precision and safety. Stone removal was accomplished in a traditional manner using an ultrasonic lithotripter. In addition, renal mapping using flexible endoscopy from above and below was performed.

8. Insert an antegrade double-pigtail stent without fluoroscopy. Following removal of all stone, the dual-lumen catheter was used to pass a glidewire into the bladder (Figure 8, A). Under direct ureteroscopic vision, the distal end of the stent was positioned in the bladder (Figure 8, B). The proximal end was positioned under direct nephroscopic vision (Figure 8, C).

9. Insert nephrostomy under direct vision. Using the through-and-through wire, a 5F multipurpose access catheter was positioned in the ureter under nephroscopic vision (Figure 9, A). Next, the flexible nephroscope was positioned in the renal pelvis with the tip of the scope in the desired location of the tip of the nephrostomy tube. A 22F council-tipped catheter was then inserted this same distance (Figure 9, B). At this point, 1 full dose fluoroscopy was used to look for any residual fragments.

10. Optimize all operating room conditions to minimize radiation usage. A dedicated radiology technician selected the optimal settings. The surgeon activated the C-arm using lighted foot pedals to prevent inadvertent activation in the dark environment (Figure 10, A). All forms of shielding were used and fluoroscopy times were tracked and reported (Figure 10, B).

The operative time in this complicated case was 3.5 hours and total fluoroscopy time was 12.1 seconds. The patient was discharged on postoperative day 1 with a stable hemoglobin of 13.8 mg/dL and was stone-free on low-dose CT. In this complicated cirrhotic patient, using this hybrid “Laser DARRT” technique, combining the optimal features of ultrasound, fluoroscopy, ECIRS, and laser guidance, this patient achieved an ideal outcome with an extremely low radiation exposure in accordance with the principles of ALARA.