title: CT-Based Determination of Ureteral Stone Volume: A Predictor of Spontaneous Passage.
abstract: OBJECTIVE
  Which ureteral stone can pass spontaneously? It is hard to answer this question exactly. The size and location of the stone are the most important predictors. However, there is still a considerable gray zone that needs to be clarified. We try to identify the role of stone volume (SV) in the prediction of spontaneous passage (SP).
  
  
  METHODS
  Seventy-eight patients with a solitary ureteral stone were retrospectively evaluated. Ureter SV measurements were taken in three planes and were calculated using the following formula: V = (X) × (Y) × (Z) × 0.52. SVs, and the longest diameters (LDs) were compared between patients who passed stones spontaneously and those who needed intervention.
  
  
  RESULTS
  The SVs and LDs were significantly lower in patients who passed stones spontaneously than in patients who required intervention (41.2 ± 35.5 vs 128.1 ± 91.1 mm(3), p = 0.001; 5.7 ± 1.8 vs 7.4 ± 1.7 mm, p = 0.001). The optimum cutoff values were 7.0 mm and 52.6 mm(3) for the LD and SV, respectively. For those stones of ≤7 mm, the volumes of the stones that could and could not pass did not differ significantly. However, the volume of the stones >7.0 mm that could pass was significantly higher than of those that could not. SP was 30.6% for stones >7 mm; however, when we removed the stones >52.6 mm(3), SP increased to 75% for stones higher than 7 mm (p = 0.001).
  
  
  CONCLUSIONS
  To classify ureteral stones using only one parameter such as stone diameter may lead to heterogeneity within the group. SV may be used in addition to size to determine a more definite homogeneous group to predict SP more precisely.
authors.affiliation: 1 Department of Urology, School of Medicine, Recep Tayyip Erdoagan University , Rize, Turkey .
authors.forename: Orhan Ünal
authors.initials: OÜ
authors.lastname: Zorba
authors.affiliation: 2 Department of Radiology, School of Medicine, Recep Tayyip Erdoagan University , Rize, Turkey .
authors.forename: Sabri
authors.initials: S
authors.lastname: Ogullar
authors.affiliation: 1 Department of Urology, School of Medicine, Recep Tayyip Erdoagan University , Rize, Turkey .
authors.forename: Selim
authors.initials: S
authors.lastname: Yazar
authors.affiliation: 1 Department of Urology, School of Medicine, Recep Tayyip Erdoagan University , Rize, Turkey .
authors.forename: Gorkem
authors.initials: G
authors.lastname: Akca
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008096:Lithotripsy / Q000706:statistics & numerical data*; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012075:Remission, Spontaneous; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D014514:Ureteral Calculi / Q000000981:diagnostic imaging* / Q000628:therapy; D018666:Ureteroscopy / Q000706:statistics & numerical data*; D055815:Young Adult