Experience of percutaneous access under ultrasound guidance in renal transplant patients with allograft lithiasis

Objective: Urolithiasis of the transplanted kidney has an incidence of 0.2 to 1.7%, it increases the risk of infection in immunosuppressed patients and it can lead to ureteral obstruction that is often associated with deterioration of renal function. Urolithiasis of the transplanted kidney has different characteristics compared to the native kidney, due to the absence of innervation, which does not lead to colic pain. Percutaneous approach is an optimal choice in transplant patients. Material and methods: Here we report our experience in two cadaveric transplant patients with urolithiasis. The first case was a patient of 68 years with a 20 mm stone located in the transplanted kidney pelvis and another smaller in a lower calyx. The second case was a patient of 65 years with a 15 mm stone in the distal part of the transplanted ureter. In both cases the patients were asymptomatic, but they had a reduction in urine output associated with worsening of the transplanted kidney function. The diagnosis was performed in both cases with ultrasound study, showing a severe hydronephrosis and it was confirmed by computed tomography scan. In both cases, we performed a Percutaneous Nephrolithotomy (PCNL). Access was made after targeting the stone, through a lower pole puncture under ultrasound guidance. The first case was treated with pneumatic and laser energy, breaking stones through a nephroscope. In the second case we performed a laser lithotripsy of the ureteral stone, using a flexible videoureteroscope. At the end of both procedures a Double-J stent and a 14 Fr Malecot nephrostomy were positioned, that were removed at 6 weeks and 10 days, respectively. Results: Both patients achieved a resolution of the worsening of renal function, recovering the spontaneous diuresis. The surgical procedure using ultrasound guidance was safe and allowed quick access to the renal pelvis. Both patients experienced no bleeding or infection during hospitalization. Conclusions: Percutaneous Nephrolithotomy (PCNL) is an established safe and effective surgical treatment option for larger renal calculi in renal allografts. The ultrasound guided access to the transplanted kidney in percutaneous treatment of urolithiasis is useful and fast, minimizing patient exposure to ionizing radiation.