Post-URS fragments consequential regardless of size

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“Patients should be informed of the less-than-ideal stone-free rates and secondary morbidity when residual fragments are present after this treatment modality,” says researcher Igor Sorokin, MD.

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%.

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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.

Next: "Patients should be informed of the less-than-ideal stone-free rates and secondary morbidity when residual fragments are present after this treatment modality"“Based on our collective findings, patients should be informed of the less-than-ideal stone-free rates and secondary morbidity when residual fragments are present after this treatment modality. Further study is needed to investigate techniques to improve stone-free rates and limit retreatment,” he added.

Outcomes of the patients included in the present study were collected based on findings from return office visits with x-rays. In addition, all patients were contacted by telephone to identify those who might have sought care at another institution for a stone-related event.

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On CT imaging, the largest mean residual fragment per patient was 3.9±2.0 mm. Thirteen of the residual fragments were >4 mm. Of the eight cases of surgical intervention, four were performed for residual fragments >4 mm.

Dr. Sorokin noted that consistent with the UT Southwestern study, a published report from the Endourology Disease Group for Excellence (EDGE) Research Consortium found that stone-related events were common in patients with residual fragments after ureteroscopy (J Urol 2016; 195:982-6). In contrast to the study from UT Southwestern Medical Center, however, the EDGE study found that fragment size predicted a need for intervention and that fragments >4 mm were associated with more complications.

“The EDGE study included data from 232 patients with residual fragments after ureteroscopy. If our study had a larger sample size, perhaps, we would have found that the association between fragment size >4 mm and needing surgical intervention was statistically significant,” Dr. Sorokin said.