Presented by: Anne Hong MD
Austin Health

Introduction

Elevated intrarenal pressures (IRPs) are common during ureteroscopies and may have implications for post operative complications. However, little is known about the microscopic processes that transpire during pathogenesis complications. We aimed to document the histological changes observed in renal units subjected to elevated IRPs and postulate the possible mechanisms of infectious complications.

Materials

21 ex vivo porcine kidney models were used. Each ureter was cannulated with a 10Fr dual lumen ureteric catheter (Boston Scientific, Massachusetts, United States) with the proximal end at the pelviureteric junction. The distal end of the ureter was secured to form a leak-proof seal around the ureteric catheter. A 0.014” pressure sensing wire (Comet II Pressure Guidewire®, Boston Scientific, Massachusetts, United States) was inserted through one lumen and with the sensor positioned in the renal pelvis for IRP measurement. Undiluted India ink stain (Royal Talens, Apeldoorn, Netherlands) was irrigated through the second lumen. Each renal unit was subjected to India ink Irrigation at target IRPs of 5mmHg (control), 30mmHg, 60mmHg, 90mmHg, 120mmHg 150mmHg and 200mmHg. 3 renal units subjected to each target IRP. After irrigation, each renal unit was processed by a uropathologist with haematoxylin and eosin, and examined under low and high power magnification.

Results

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India ink stain was observed in the collecting ducts at 5mmHg. Signs of pressure as represented by collecting duct dilatation was first observed at 60mmHg (Figure A). Stain was consistently observed in the distal convoluted tubules at ≥60mmHg, all renal units showed renal cortex involvement. At ≥90mmHg, stain was observed in venous structures (Figure B). At 200mmHg, stain was observed in supportive tissue, peritubular capillaries and glomerular capillaries.

Conclusion

Demonstration of vascular involvement is required to account for septic complications. This occurred at IRP of ≥90mmHg in ex vivo porcine models.

Funding

The authors did not receive any funding for this research

Co-Authors

Justin Du Plessis, MD
Austin Health

Greg Jack, PhD
Austin Health

Cliodhna Browne, MD
Austin Health

Damien Bolton, MD, PhD
Austin Health