title: Natural History of Residual Fragments After Percutaneous Nephrolithotomy: Evaluation of Factors Related to Clinical Events and Intervention.
abstract: To determine the natural history of residual fragments (RF) after percutaneous nephrolithotomy in long-term patient follow-up and to identify possible predictive factors for future intervention.
  
  
  
  We assessed all patients from 2006 to 2013 with postoperative computed tomography scan revealing RF, who did not undergo second-look nephroscopy or immediate ancillary procedures, and with at least 12 months of clinical follow-up. We evaluated factors associated with clinical, radiological, and surgical outcomes. Kaplan-Meier curves were used to calculate the proportion of asymptomatic and treatment-free patients during follow-up.
  
  
  
  From 781 percutaneous nephrolithotomies performed, 202 patients underwent postoperative computed tomography scan and 44 patients with residual stones were included in the analysis. Mean follow-up was 57.9 months. A total of 24 patients (54.5%) developed at least 1 clinical outcome, and 32 (72.7%) patients had a surgical intervention. Only 4 patients had radiological evidence of stone passage. Multivariate analysis found that RF >4 mm and struvite or apatite stones were significant predictors for surgical intervention. The 5-year estimated probability to remain intervention free was 29%.
  
  
  
  Despite the size of the RF, the vast majority of patients required an intervention during long-term follow-up. We identified that RFs of diameter >4 mm associate with the need for a surgical therapy, but the rate of clinical events was not affected by the size or location of the stones. Struvite or apatite composition stones had an increased risk of intervention during follow-up. Spontaneous passage was an uncommon event in this cohort.
authors.affiliation: Division of Urology, Department of Surgery, Schulich School of Medicine and Dentistry, The University of Western Ontario, St. Joseph's Hospital, London, Ontario, Canada; Instituto de Cirugía, Tec Salud, Monterrey, Mexico.
authors.forename: Daniel
authors.initials: D
authors.lastname: Olvera-Posada
authors.affiliation: Division of Urology, Department of Surgery, Schulich School of Medicine and Dentistry, The University of Western Ontario, St. Joseph's Hospital, London, Ontario, Canada.
authors.forename: Sohrab Naushad
authors.initials: SN
authors.lastname: Ali
authors.affiliation: Division of Urology, Department of Surgery, Schulich School of Medicine and Dentistry, The University of Western Ontario, St. Joseph's Hospital, London, Ontario, Canada.
authors.forename: Marie
authors.initials: M
authors.lastname: Dion
authors.affiliation: Division of Urology, Department of Surgery, Schulich School of Medicine and Dentistry, The University of Western Ontario, St. Joseph's Hospital, London, Ontario, Canada.
authors.forename: Husain
authors.initials: H
authors.lastname: Alenezi
authors.affiliation: Division of Urology, Department of Surgery, Schulich School of Medicine and Dentistry, The University of Western Ontario, St. Joseph's Hospital, London, Ontario, Canada.
authors.forename: John D
authors.initials: JD
authors.lastname: Denstedt
authors.affiliation: Division of Urology, Department of Surgery, Schulich School of Medicine and Dentistry, The University of Western Ontario, St. Joseph's Hospital, London, Ontario, Canada. Electronic address: Hassan.Razvi@sjhc.london.on.ca.
authors.forename: Hassan
authors.initials: H
authors.lastname: Razvi
mesh_terms: D001031:Apatites / Q000032:analysis; D005260:Female; D021501:Flank Pain / Q000209:etiology; D005500:Follow-Up Studies; D006801:Humans; D007669:Kidney Calculi / Q000737:chemistry / Q000000981:diagnostic imaging* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D000074642:Nephrolithotomy, Percutaneous; D011184:Postoperative Period; D011336:Probability; D056844:Renal Colic / Q000209:etiology; D012086:Reoperation; D012189:Retrospective Studies; D012307:Risk Factors; D000069877:Struvite / Q000032:analysis; D013997:Time Factors; D014057:Tomography, X-Ray Computed
chemical_list: D001031:Apatites; D000069877:Struvite