Ureteroscopy is associated with a low stone-free rate, and the residual fragments are consequential, regardless of size, according to research conducted at UT Southwestern Medical Center, Dallas.
In December 2015, a prospective study was launched to determine the efficacy of ureteroscopy for removing renal and ureteral stones and the clinical significance of failure to achieve stone-free status. Through February 2017, it enrolled 167 patients (209 renal units) who underwent ureteroscopy with aggressive fragment retrieval. Computed tomography imaging performed at 6 to 8 weeks after ureteroscopy identified residual fragments in 81 patients (94 renal units) for a true stone-free rate of 55%.
The analysis to determine the consequences of having residual fragments included 45 patients (53 renal units) who had at least 12 months follow-up after ureteroscopy (mean, 16.6±3.9 months), and it found that a stone event occurred in 17 (32%) of the 53 renal units.
The stone events were comprised of stone passage in five renal units (9.4%), emergency department visit without surgical intervention in two renal units (3.8%), stone growth in two renal units (3.8%), and surgical intervention in eight renal units (15%). A multivariate analysis failed to identify any independent predictors of a stone event, but there was a trend for residual fragments >4 mm to be associated with an increased need for surgical intervention (p=.14), first author Igor Sorokin, MD, reported at the AUA annual meeting.
“Other investigators relying on ultrasound or x-ray for follow-up imaging and counting only larger residual fragments have reported ureteroscopy provides stone-free rates of between 75% and 90%. Using more sensitive imaging and including all residual fragments, however, we found only about 55% of patients achieve stone-free status. Furthermore, our research dispels the idea that the residual fragments are clinically insignificant,” said Dr. Sorokin, who worked on the research with Margaret S. Pearle, MD, PhD, and colleagues.