Case Studies
Case studies showcase real-world applications of policies and innovations, offering insights into improving outcomes and efficiency. They enhance problem-solving skills, highlight best practices, and engage through storytelling for education and transparency.
You’re Killing Me: The Unintended Consequences of Renal Wedge Biopsies
Chris
Jaynes
, PhD Candidate
, CEO
, 34 Lives, PBC
The Challenge
As the US deceased donor population becomes more extended, with more donation after cardiac death (DCD) and older donors with higher KDPI’s, renal biopsies have become standard in nearly all donor types. Organ Procurement and Transplant Network (OPTN) policy requires renal biopsies on all kidneys from donors > 18 years old with at least one of the following criteria: anuria (< 100ml/ 24 hours), on hemodialysis or renal replacement therapy, HbA1C > 6.5, KDPI > 85%, donor age > 60 years or 50-59 years with a history of hypertension, CVA as manner of death, or terminal serum creatinine ≥ 1.5 mg/dL. The most common biopsy type in donor kidneys is a cortical wedge. We aimed to investigate if there were unintended consequences of wedge biopsies to the donor kidney in terms of perfusion artifacts.
The Approach
Human donor kidneys with cortical wedge biopsies that were initially recovered from deceased donors with the intent to transplant (i.e. flushed and packaged according to OPTN policy for transplantation), but were unused, were sent to a centralized normothermic perfusion center (“34 Lives”) for research purposes. Six kidneys were perfused sub-normothermically (35oC) for up to 6 hours using an acellular (i.e. no red blood cell) perfusate (“SNAP”), during which time they were imaged using either a 3T Siemens MRI or a Stryker SPI-PHI fluorescent ICG imager. Perfusion parameters and global perfusion images from each imaging device were recorded.
The Results
All kidneys had significantly worse perfusion downstream of the cortical wedge biopsy site visualized by MRI (n=2) and ICG dye (n=4). In one case approximately 30% of the kidney had no perfusion in the MRI for the entire 6 hours (Figure 1). In all 4 of the SPY-PHI fluorescent images, a significant lack of perfusion was evident in large segments and even along the spine of the kidney (Figure 2). One kidney (Figure 2A and 2B) had globally poor flow and high resistance measured during SNAP. Interestingly, the other 5 kidneys had no significant measured perfusion changes (flow, pressure, resistance) during either hypothermic machine perfusion (HMP) or SNAP and would have been considered suitable for transplantation based only on perfusion parameters.
Insights & Lessons Learned
Our small study suggests that cortical wedge biopsies can infarct and significantly decrease viable nephron mass in kidneys recovered with the intent to transplant. While renal biopsies continue to be the standard of care in donor kidney assessment, wedge biopsies should be avoided in favor of assessments that cause less trauma. Ideally, emerging non-invasive techniques to visualize kidney function and fibrosis during SNAP will one day replace the need for biopsies altogether.