Clinical effectiveness protocols for imaging in the management of ureteral calculous disease: AUA technology assessment.

PURPOSE: This technology assessment addresses the optimal use of imaging in the evaluation and treatment of patients with suspected or documented ureteral stones. MATERIALS AND METHODS: A comprehensive literature search addressing 4 guiding questions was performed for full text in English articles published between January 1990 and July 2011. The search focused on major subtopics associated with the imaging of ureteral calculi, and included specific imaging modalities used in the diagnosis and management of ureteral calculous disease such as unenhanced (noncontrast) computerized tomography, conventional radiography, ultrasound, excretory urography, magnetic resonance imaging and nuclear medicine studies. Protocols (in the form of decision tree algorithms) were developed based on this literature review and in some instances on panel opinion. The 4 questions addressed were 1) What imaging study should be performed for suspected ureteral calculous disease? 2) What information should be obtained? 3) After diagnosis of a ureteral calculus, what followup imaging should be used? 4) After treatment of a ureteral calculus, what followup imaging studies should be obtained? RESULTS: Based on these protocols, noncontrast computerized tomography is recommended to establish the diagnosis in most cases, with a low energy protocol advocated if body habitus is favorable. Conventional radiography and ultrasound are endorsed for monitoring the passage of most radiopaque stones as well as for most patients undergoing stone removal. Other studies may be indicated based on imaging findings, and patient, stone and clinical factors. CONCLUSIONS: The protocols generated assist the clinician in establishing the diagnosis of ureteral calculous disease, monitoring stone passage and following patients after treatment. The protocols take into account not only clinical effectiveness but also cost-effectiveness and risk/harm associated with the various imaging modalities.

Calcium phosphate content does not affect stone-free rate after percutaneous nephrolithotomy.

PURPOSE: Recent research suggests that the stone-free rate for percutaneous nephrostolithotomy is lower in patients with calcium phosphate stones than in those with stones of other compositions. We reviewed our percutaneous nephrostolithotomy outcomes to investigate this unexplained finding. MATERIALS AND METHODS: A total of 188 patients with sufficient data available for review underwent unilateral percutaneous nephrostolithotomy at our institution between September 2005 and May 2007. Patients were analyzed based on stone burden (including 2 cm or less, greater than 2 cm, partial staghorn calculus and complete staghorn calculus). Stones were also stratified by calcium phosphate content (0%, 1% to 10%, 11% to 60% and greater than 60%). To remain consistent with the previous study procedural failure was classified as greater than 2 mm residual stone fragments identified by unenhanced computerized tomography on postoperative day 1 regardless of the ultimate stone-free rate after secondary procedures. Multivariate logistic regression analysis was done to identify factors predicting a failed procedure. RESULTS: Of the patients 101 (54%) were male and 132 (71%) were recurrent stone formers. Overall 107 cases (57%) had calcium phosphate as a stone component and 37.8% were classified as failures. Increasing stone size was associated with a decreased stone-free rate (p = 0.009). The failure rate was 37%, 46.4%, 38.1% and 32.4% for patients with a 0%, 1% to 10%, 11% to 60% and greater than 60% calcium phosphate stone content (p = 0.68). On multivariate logistic regression analysis no association was noted between calcium phosphate content and greater than 2 mm residual stones (p = 0.67). CONCLUSIONS: Calcium phosphate stone composition does not predict a poor stone-free rate after percutaneous nephrostolithotomy.

[Vitamin C and stone risk. Review of the literature]. / Vitamine C et risque lithiasique.

The popularity of vitamin C can be attributed to Linus Pauling who, in the 1970s, recommended the use of vitamin C for the prevention of influenza. Vitamin C has subsequently been used extensively in a wide range of diseases. Ascorbic acid (vitamin C) has been incriminated as a possible risk factor for calcium oxalate stones due to its enzymatic conversion into oxalate. However, this lithogenic role has never been clearly established. Studies evaluating the effect of ascorbic acid on lithogenesis have reported contradictory results. Ascorbic acid has also been extensively used as an urine acidifier for the treatment of chronic or recurrent urinary tract infection. Once again, the data of the literature are contradictory. The purpose of this article was to review the effects of ascorbic acid on lithogenesis and urinary pH based on a review of the literature.