Category: Clinical Stones: SWL

MP9-17 - Use of abdominal plain film versus ultra-low dose computed tomography for assessment of stone free rates after shock wave lithotripsy: implications for subsequent emergency department visits and unplanned lithotripsy procedures

Fri, Sep 21
2:00 PM - 4:00 PM

Introduction & Objective :

Ultra-low dose CT (ULD-CT) offers superior resolution, with equivalent radiation exposure, to a 2-view KUB. We undertook a retrospective-study to assess the impact of imaging modality (ULD-CT versus KUB) on stone-free-rates (SFR), and subsequent emergency department (ED) utilization and unplanned lithotripsy procedures.

Methods : Medical charts of patients undergoing SWL between Jan-2015 and Jun-2016 were retrospectively reviewed (n=248). All patients underwent KUB/ULD-CT at 3-6 weeks and were followed for 3-6 months; patients lacking follow-up were excluded (n=35). Outcomes studied were: 1. ED-utilization and 2. unplanned lithotripsy procedure, defined as a procedure on the side of the SWL within 3-months following ‘negative’ postoperative imaging. 

Results :

The patients were well matched on baseline/stone-related characteristics (Table). The SFR in KUB cohort was 78.3% (n=134) and in ULD-CT cohort was 64.2% (n=27 [p=0.057]). 2/27 patients (7.4%) deemed stone-free on ULD-CT returned to ED within 3-months, while 17/134 patients (12.7%) deemed stone-free on KUB returned to ED during the same time-period (p=0.437). 1/27 patient (3.7%) needed an unplanned surgery in the ULD-CT group, while 13/134 patients (9.7%) needed an unplanned surgery in the KUB group (p=0.311; Figure).

Conclusions :

ULD-CT may offer a better estimate of true SFR, and may mitigate unwanted ED and return-to-operating-room visits. Prospective studies may be warranted to evaluate this question further. 

Philip Wong

Detroit, Michigan

Akshay Sood

Detroit, Michigan

Chase Heilbronn

Detroit, Michigan

Matthew Hanna

Detroit, Michigan

Ben Eilender

Detroit, Michigan

David A. Leavitt

Henry Ford Health System
Detroit, Michigan