Page 6 - CUA2019 Abstracts - Endourology

Poster session 3: Endourology

MP-3.15 Conclusions: One SWL procedure offers a stone-free rate of 78.8%, and
A comparison of potential clinical and metabolic determinants after two SWLs, an 87.5% stone-free rate. Only 12.5% of patients under-
favouring calcium oxalate monohydrate vs. dihydrate stone going SWL at our centre required ureteroscopy to achieve a stone-free
formation status. SWL is an effective modality in the treatment of distal ureteral
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Noah Stern , Jennifer Bjazevic , Linda Nott , Hassan Razvi 1 stones. Further studies investigating quality of life may show SWL is an
1 Department of Surgery, Division of Urology, Schulich School of Medicine even better choice for distal ureteral stones.
& Dentistry, Western University, London, ON, Canada
Introduction: The majority of urinary stones are predominantly calcium UP-3.1
oxalate (CaOx) in composition and can be found in two main chemical Targeting a stone staging system: Categorizing long-term urinary
forms: calcium oxalate monohydrate (COM) and dihydrate (COD). COM stone event rates
stones are known to be more difficult to fragment, especially with shock Mark Assmus , Nick Dean , Betty Wang , Shubha De , Trevor D. Schuler ,
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wave lithotripsy, which can have important implications for the suc- Tim Wollin 1
cess rates of stone treatment and patient counselling regarding surgical 1 Department of Surgery, Division of Urology, University of Alberta,
options. Our study examined a large contemporary cohort to determine Edmontn, AB, Canada; Faculty of Medicine and Dentistry, University of
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potential clinical and biochemical characteristics that may favour the Alberta, Edmonton, AB, Canada
formation of COM or COD stones. The Data Integration and Management Repository (DIMR)
Methods: A retrospective analysis of a prospectively maintained metabolic Introduction: Although urinary tract calculi remain one of the most
stone clinical database from September 2001 to February 2017 was per- prevalent disease processes, there is a paucity of contemporary, long-
formed. Patients with predominantly (>50%) COM or COD stones were term stone event rate (SER) data to counsel patients with varying stone
identified and those with incorrectly collected 24-hour urine collections burdens. Attempts to incorporate stone burden have focused on surgi-
were excluded. Analysis of patient demographic data, serum and urine cal success (STONE score, Guy’s stone score) or have clinical barriers
biochemistry was performed. (ROKS nomogram). We sought to establish local SERs for a spectrum
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Results: A total of 298 patients (85.9%) with primarily COM and 49 of baseline stone burdens.
patients (14.1%) with principally COD stones were identified. COM Methods: We reviewed all computed tomography (CT)-detected urinary
patients were older (54±13 vs. 48±17 years; p=0.012). There was no tract stones in adult patients referred to four urologists from April to
correlation between gender, body mass index, medical comorbidities, September 2009. In collaboration with Data Integration and Management
family history of stone disease, or prior history of stone treatment and Repository (DIMR), demographics, and stone burden on CT, as well as
stone composition. Low urine volume was significantly associated with eight-year followup SERs were added to a REDCap database. SERs were
COD stones (p=0.006). However, there was no correlation with stone type defined as emergency department visit, urology visit, or surgery. Both t-test
and other 24-hour urine findings, including urinary pH, sodium, calcium, and Fisher’s exact two-tailed test were used, while time to SER curves
oxalate, urate, phosphate, and urea; or serum biochemistry, including were constructed by Kaplan-Meier method and analyzed by log-rank test
serum calcium, parathyroid hormone, urate, and vitamin D levels. (significance p<0.05).
Conclusions: Prior small studies have demonstrated conflicting results Results: To date, 318 adults at a mean age of 54 years (18–94) were added
between CaOx stone type and 24-hour urine results. Our study on a large to our database. Overall, 75% successfully treated their symptomatic
contemporary series fails to show an association between the usually stone with surgery, while 16% spontaneously passed their stone. Thirty-
assessed clinical and biochemical characteristics favouring the formation nine percent achieved stone-free status and were labelled “low-burden,”
of COM over COD stones. Further research is required to better elucidate S0. Sixty-one percent (195/318) of patients had additional stone(s) on
the mechanisms behind CaOx stone formation. CT, other than their treated stone(s), and were labelled S1. Overall, 32%
presented to the emergency room over eight years and 29% required
MP-3.16 additional surgery. Using univariate and multiple regression analysis, we
Extracorporeal shockwave lithotripsy in the management of identified two significant variables along with CT stone burden (low vs.
distal ureteral calculi high) in order to divide patients into three stages, each with distinct
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Justin Chan , Kymora B. Scotland , Gholamreza Safaee Ardekani , Ryan eight-year SERs across all outcomes (e.g., eight-year ER renal colic rate
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F. Paterson , Ben H. Chew 1 by stage: I – 15%, IIA – 30%, IIB – 44%, III – 51%; p<0.05).
1 Department of Urologic Sciences, University of British Columbia, Conclusions: We are completing our database and province-wide data
Vancouver, BC, Canada extraction to establish a preliminary staging system that characterizes
Introduction: Current American Urological Association guidelines rec- long-term, clinically significant SERs for both first-time and recurrent
ommend ureteroscopy as primary management of distal ureteral stones stone-formers.
and shockwave lithotripsy (SWL) as a secondary option. Use of SWL in References
the management of nephrolithiasis in North America has decreased. We 1. Rule AD, Lieske JC, Li X, et al. The ROKS nomogram for pre-
hypothesized that SWL continues to be an effective option in the manage- dicting a second symptomatic stone episode. J Am Soc Nephrol
ment of distal ureteral calculi and studied data from our centre in patients 2014;25:2878-86. https://doi.org/10.1681/ASN.2013091011
who received SWL for distal ureteral stones. 2. Molina WR, Kim FJ, Spendlove J, et al. The S.T.O.N.E. score: A new
Methods: A retrospective review was performed of 104 patients treated assessment tool to predict stone free rates in ureteroscopy from
initially with SWL for distal ureteral calculi between 2011 and 2017 at this preoperative radiological features. Int Braz J Urol 2014; 40:23-9.
institution. The success rate of SWL was assessed via radiological imaging https://doi.org/10.1590/S1677-5538.IBJU.2014.01.04
and if subsequent procedures were required to render patients stone-free. 3. Thomas K, Smith NC, Hegarty N, et al. The Guy’s stone score —
Results: Operative note and chart review identified 104 patients who grading the complexity of percutaneous nephrolithotomy proce-
presented with distal ureteral stones and were treated with SWL as the dures. Urol 2011;78:277-81.
initial form of management. Average patient age was 52.2±15.3 years,
average body mass index BMI was 27.4±5.7, and average total axial stone
surface area was 25.96±14.32 mm . Of these patients, 78.8% (n=82)
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were stone-free following one SWL and required no subsequent proce-
dures; 87.5% (n=91) were stone-free following a second SWL. After the
initial SWL, residual stones were identified in 21.2% of patients (n=22).
Of these residual stone patients, 40.9% (n=9) required a repeat SWL,
40.9% (n=9) required a ureteroscopy, and 18.2% (n=4) required a salvage
ureteroscopy following a failed second SWL to achieve a stone-free status.
CUAJ • June 2019 • Volume 13, Issue 6(Suppl5) S101