Residual stone fragments: clinical implications and technological innovations

Curr Opin Urol. 2019 Mar;29(2):129-134. doi: 10.1097/MOU.0000000000000571.


Purpose of review: To summarize the recent literature on the topic of residual stone fragments in particular novel developments in this field.

Recent findings: The urological position towards residual fragments has shifted in recent years from observation, to active retrieval with innovative methods, to algorithm-based predictions of surgical outcomes. Novel technologies have been described to extract residual fragments through magnetism, a polyethylene endoscopic pouch and a biocompatible stone adhesive. In an effort to have a tighter grip over the outcome of residual fragments, artificial neural networks (ANNs) have been developed to accurately predict surgical outcomes in terms of stone clearance and secondary procedures.

Summary: Growing evidence continues to show the term clinically insignificant residual fragments (CIRF) for residual fragments of 4 mm or less to be a misnomer. In fact, only a third of CIRF is spontaneously cleared from the kidney after surgery and may become a cause for reintervention being both costly and significantly affecting patients' well being. Several novel methods which have been developed to extract residual fragments require further in-vivo investigations to confirm their safety and efficacy. ANNs algorithms are increasingly being used to predict surgical outcomes in stone therapy and assist in preoperative patient counselling and decision-making.

Publication types

  • Review

MeSH terms

  • Disease Progression
  • Endoscopy
  • Humans
  • Inventions
  • Kidney Calculi* / therapy
  • Lithotripsy*
  • Treatment Outcome