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Ex-Vivo Ureteroscopy for Stone Retrieval in Kidney Allograft on Hypothermic Machine Perfusion: Is There a Benefit?
Xinyue Cynthia Tan, MD1, Gregory Kunkel, MD2, Igor Sorokin, MD1.
1UMass Chan Medical School, Worcester, MA, USA, 2St. Luke's University Health Network, Bethlehem, PA, USA.
BACKGROUND: Kidney stones in allografts are no longer a contraindication for transplantation. Ex-vivo ureteroscopy (URS) prior to allograft transplantation is a minimally invasive treatment option for stone removal. Maintaining the allograft on hypothermic machine perfusion (HMP) maximizes preservation of the graft during ex-vivo ureteroscopy. This case series describes a single-center's experience with ex-vivo ureteroscopy on and off HMP.
METHODS: This was a retrospective, single-center, multi-surgeon study of ex-vivo ureteroscopy and stone retrieval performed on and off HMP between 12/2021 and 1/2025. Patient charts were reviewed for post-operative renal function, hydronephrosis and nephrolithiasis.
RESULTS: Of 11 cases, 5 were performed off HMP and 6 were performed on HMP. Both groups had similar ischemic time. Most cases had small stones requiring basket extraction with URS. One case required laser lithotripsy for stone removal. Two patients in the off-HMP group and three patients in the HMP group required dialysis post-operatively. Two patients developed mild pelviectasis/ hydronephrosis on surveillance transplant ultrasound post-operatively (3 and 10 months post-op). One of these patients (off HMP) had transplant failure secondary to biopsy-proven rejection requiring dialysis and implantation of new renal allograft. Two patients in the HMP URS group developed evidence of recurrent nephrolithiasis in transplant kidney on US. No patients have presented with symptomatic nephrolithiasis or hydronephrosis of transplant kidney impacting renal function. Median follow up duration was 24 months, with longest follow up duration being 46 months.
CONCLUSIONS: This study adds to the literature demonstrating ex-vivo URS with stone removal is a safe method to improve kidney allograft utilization, both on and off HMP. Remaining on HMP for URS immediately prior to transplantation does not appear to impact outcomes.
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