Category: Clinical Stones: PCNL

MP7-7 - Increasing body mass index lengthens the learning curve for ultrasound-guided percutaneous nephrolithotomy

Fri, Sep 21
10:00 AM - 12:00 PM

Introduction & Objective :

To define how the learning curve for success in ultrasound-guided PCNL is impacted by body mass index (BMI). Previous research has shown ultrasound-guided percutaneous nephrolithotomy (PCNL) to be an effective method of nephrolithiasis treatment comparable to fluoroscopy guided PCNL. A common concern for the ultrasound-guided approach is potential imaging difficulty in the obese patient population.

Methods :

A prospective cohort study of consecutive patients undergoing PCNL with ultrasound guidance for renal tract access was performed. Clinical data collected included successin gaining renal access with ultrasound guidance, patient BMI, and clinical outcomes over time. Nonparametric LOWESS regression modeling was performed in R using locally weighted scatterplot smoother (R version 3.3.3) for gradations of patients by BMI group (40).

Results :

A total of 150 cases were examined. Case number and BMI were evaluated as continuous variables. Multivariate logistic regression revealed that BMI (p = 0.010; OR 0.93) and case number (p<0.001; OR 1.03) were significantly correlated with ultrasound success. Sex, age, hydronephrosis, stone type, puncture location, and stone size did not influence success at obtaining ultrasound-only access in a statistically significant fashion. LOWESS regression modeling of the relationship between case number and renal access success depicts the curve representative of the BMI>40 group is downward and right-shifted relative to the other two groups<./p>

Conclusions :

The learning curve for successful ultrasound-guided PCNL is impacted by patient BMI as well as case number. Increasing BMI makes access more challenging when performing ultrasound-guided PCNL.

David Bayne

Clinical Fellow
San Francisco, California

David Bayne, MD, MPH
UCSF Urology Endo/Lap Fellow
Pager: 415-443-4394
Cellphone: 617-571-5870

BA in Biochemistry at Harvard College 2006
MD at Harvard Medical School 2012
MPH at UC Berkeley in 2017
Residency in Urology at UCSF 2018

Manint Usawachintachit

Bangkok, Krung Thep, Thailand

David T. Tzou

Assistant Professor
University of Arizona
Tucson, Arizona

Kazumi Taguchi

San Francisco, California

Alan Shindel

San Francisco, California

Thomas Chi

Associate Professor
San Fransisco, California

Thomas Chi, MD
Associate Professor
Associate Chair for Clinical Affairs
Kutzmann Endowed Professor for Clinical Urology
UCSF Department of Urology

Dr. Thomas Chi, MD, graduated as a President's Scholar from Stanford University with a BA in Human Biology and MAs in Sociology and Music. He earned his MD from the University of California, San Francisco where he also completed urology residency and a fellowship in Endourology and Laparoscopy under the mentorship of Dr. Marshall L. Stoller.

During his fellowship, Dr. Chi was awarded grant funding from the National Institutes of Health and the American Urological Association Urology Care Foundation to research the fundamental mechanisms underlying the formation of urinary stones.

Clinical Interests

He joined the UCSF faculty of the Department of Urology in 2013 where his clinical interests include the care of patients with urinary stone disease and those in need of minimally invasive surgery. He specializes in the performance of endoscopic, laparoscopic, and percutaneous surgeries as well as HoLEP. He has established ReSKU, the Registry for Stones of the Kidneys and Ureter, the first kidney stone registry of its kind for tracking patient clinical outcomes and is an internationally recognized specialist in the use of ultrasound in the management of kidney stones to minimize patient radiation exposure.

Research Interests

In addition to his clinical interests, Dr. Chi supervises an NIH-funded translational science lab where he leads a cross-disciplinary research team. His research focuses on understanding the genetic and microbial environment of the kidney related to how kidney stones form and developing new medical preventative interventions. He has developed a novel model fruit fly for the study of kidney stones and has published over 80 peer-reviewed articles and book chapters spanning both basic science as well as epidemiologic approaches centered around improving the care of patients with urinary stone disease.