WCE 2019: Plenary DEBATE: Where’s the Evidence Residual Fragments: Active Intervention vs Surveillance

Abu Dhabi, United Arab Emirates (UroToday.com) Dr. Kenneth Pace began his argument in favor of active surveillance of calcium oxalate fragments with an overview of residual stone fragment detection. Dr. Pace stated that we should be calling any fragments “clinically insignificant” because in reality, even small, fragments can cause stone-related events. From Dr. Pearle’s 1999 study, CT scan is the gold standard of fragment detection, although it can overcall fragment size and a 12% false positive rate.1 

Dr. Pace then presented a case of a patient with an asymptomatic, 3mm lower calyceal calcium oxalate fragment. The natural history of such calyceal stones is such that 50-80% of patients who have them do not require intervention within five years of follow-up.2 After ureteroscopy, 56% of patients required no further intervention, particularly in the group with fragments less than 4 mm fragments.3 After percutaneous nephrolithotomy, even with fragments greater than 6mm, many patients passed their fragments within 3 months. Small fragments were even less likely to cause problems, with no patients with fragments smaller than 2mm requiring any intervention within 41 months. In summary, approximately 75% of small residual do not cause issues over time. Dr. Pace stressed that urologists must avoid overtreatment, which means that physicians should not discharge patients from follow-up in order to properly identify patients who do need secondary intervention if that becomes necessary.

Dr. Arkadiusz Miernek argued in favor of active intervention. He believes that the term “clinically insignificant residual fragment” is a misnomer as all residual fragments require close monitoring for stone growth, potential complications, and subsequent intervention.4 Stone fragment growth and passage are independent of stone size. His belief that fragments should be intervened on is grounded in the European Association of Urology (EAU) guidelines, which recommends that secondary intervention be considered because 21-59% of patients require retreatment within 5 years.5 Furthermore, the American Urology Association goes further and recommends that all patients with greater than 2mm residual fragments be offered endoscopy.6 Of note, Dr. Miernek mentioned is that patients who do have spontaneous stone passage after surgical intervention are very unhappy, so secondary intervention should be offered preemptively.

Dr. Pace rebutted Dr. Miernek’s points with the discussion by citing the very same EAU guidelines, which state that urologists should be vigilant against overtreatment due to the fact that over half of patients will not have a stone-related event during follow-up.5 In addition, new technology presented at this World Congress has shown that ultrasonography can be used to propel fragments down the ureter and thulium fiber lasers give rise to true stone dusting, which could eliminate fragments altogether.

Dr. Miernek replied to these arguments by stating that it is important to understand individualized patient care. From his point of view, residual fragments are clinically important in particular for low-risk stone formers who will benefit from complete stone clearance. Proper patient follow-up and counseling are extremely important.

Presented by: Kenneth Pace, MD, MSc, FRCSC, University of Toronto (for Surveillance); Arkadiusz Miernek, MD, PhD, FEBU, University Medical Center Freiburg (for Active Intervention)

Written by: Lillian Xie, BA, Department of Urology, University of California, Irvine, California at the 37th World Congress of Endourology (WCE) – October 29th-November 2nd, Abu Dhabi, United Arab Emirates   

1. Pearle MS, Watamull LM, Mullican MA. Sensitivity of noncontrast helical computerized tomography and plain film radiography compared to flexible nephroscopy for detecting residual fragments after percutaneous nephrostolithotomy. J Urol. 1999;162(1):23-6.
2. Osman Y, Harraz AM, El-nahas AR, et al. Clinically insignificant residual fragments: an acceptable term in the computed tomography era?. Urology. 2013;81(4):723-6.
3. Chew BH, Brotherhood HL, Sur RL, et al. Natural History, Complications and Re-Intervention Rates of Asymptomatic Residual Stone Fragments after Ureteroscopy: a Report from the EDGE Research Consortium. J Urol. 2016;195(4 Pt 1):982-6.
4. Tan YH, Wong M. How significant are clinically insignificant residual fragments following lithotripsy?. Curr Opin Urol. 2005;15(2):127-31.
5. Türk, Christian, et al. “EAU Guidelines on Interventional Treatment for Urolithiasis.” European Urology, vol. 69, no. 3, June 2018, pp. 475–482, www.sciencedirect.com/science/article/pii/S0302283815007009, 10.1016/j.eururo.2015.07.041.
6. Assimos, Dean, et al. “Surgical Management of Stones: American Urological Association/Endourological Society Guideline, PART I.” Journal of Urology, vol. 196, no. 4, Oct. 2016, pp. 1153–1160, www.sciencedirect.com/science/article/pii/S0022534716305316, 10.1016/j.juro.2016.05.090. Accessed 31 Oct. 2019.