Exploring ureteroscope design with computational fluid dynamics for improved intra-pelvic pressure

Area of Science:

• Urology
• Medical Devices
• Computational Fluid Dynamics

Background:

• High intra-pelvic pressure (IPP) during ureteroscopy is linked to serious complications such as pyelovenous backflow, bleeding, and infection.
• Optimizing the configuration of the ureteroscope and Ureteral Access Sheath (UAS) is crucial for improving safety and efficacy during ureteroscopic procedures.

Purpose of the Study:

• To determine the optimal cross-section and orientation of a ureteroscope within a UAS to minimize IPP and maximize fluid outflow.
• To validate the findings by creating and testing a prototype UAS designed to offset the ureteroscope.

Main Methods:

• Computational fluid dynamics (COMSOL) simulations were used to model four ureteroscopes of equivalent cross-sectional area within a 10 Fr UAS.
• A prototype UAS was created by offsetting a 9.5-Fr flexible ureteroscope within a 12 Fr UAS using a monofilament suture.
• Fluid flow volumes were compared between the standard and prototype UAS configurations.

Main Results:

• Simulations showed that an offset circular ureteroscope resulted in 41% less resistance, lower IPP, and higher outflow compared to a centered ureteroscope.
• The modified UAS prototype demonstrated a 12.5% increase in mean flow volume (33.76 mL/min) compared to the unmodified UAS (30.0 mL/min) (p < 0.05).
• Positioning the ureteroscope along the sidewall of the UAS maximizes outflow.

Conclusions:

• Positioning a circular ureteroscope offset within a circular UAS maximizes fluid outflow.
• A prototype UAS designed to offset the ureteroscope achieved a significant increase in outflow, potentially reducing IPP during ureteroscopy.
• This offset strategy offers a method to enhance fluid dynamics without compromising the working channel or inflow.