Document Detail

Limitations to ultrasound in the detection and measurement of urinary tract calculi.
MedLine Citation:
PMID:  20206970     Owner:  NLM     Status:  MEDLINE    
OBJECTIVES: To evaluate differences in stone measurement using computed tomography (CT) and ultrasound (US). Axial unenhanced helical CT is the reference-standard imaging modality for the assessment of urinary tract calculi; however, US is also commonly used. Differences in stone measurement using these techniques are poorly described and contributors to measurement error remain unknown.
METHODS: All patients at our institution undergoing both abdominal CT and renal US less than 1 month apart since June 2004 were reviewed. Solitary renal calculi were identified on both CT and US in all cases.
RESULTS: We identified 71 calculi in 60 patients. Compared with CT, US overestimated stone size, an effect that was more pronounced with smaller calculi. The mean stone measurement on CT was 7.4 +/- 4.4 mm and on US it was 9.2 +/- 4.5 mm (P = .018). For stones </=5 mm, US measurements were a mean of 1.9 +/- 1.2 mm greater than CT (P <.001). US and CT measurements were discordant for 60% of stones </=5 mm. Discordance was associated with US measurement of skin-to-stone distance (P = .018), but not body mass index (P = .189) or location within the urinary tract (P = .161). Review of the literature revealed that US has a pooled sensitivity and specificity of 45% and 94%, respectively, for the detection of ureteric calculi and 45% and 88%, respectively, for renal calculi.
CONCLUSIONS: US overestimates stone size in urolithiasis, a finding that may have implications for stone management. Discordance in stone measurement varies with size and is greatest in stones </=5 mm. US measurement of skin-stone-distance is an important determinant of error in US measurement of renal calculi.
A Andrew Ray; Daniela Ghiculete; Kenneth T Pace; R John D'A Honey
Publication Detail:
Type:  Comparative Study; Journal Article     Date:  2010-03-05
Journal Detail:
Title:  Urology     Volume:  76     ISSN:  1527-9995     ISO Abbreviation:  Urology     Publication Date:  2010 Aug 
Date Detail:
Created Date:  2010-08-10     Completed Date:  2010-09-13     Revised Date:  2011-01-14    
Medline Journal Info:
Nlm Unique ID:  0366151     Medline TA:  Urology     Country:  United States    
Other Details:
Languages:  eng     Pagination:  295-300     Citation Subset:  IM    
Copyright Information:
Copyright 2010 Elsevier Inc. All rights reserved.
Department of Urology, St. Michael's Hospital, University of Toronto, Toronto, Canada.
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MeSH Terms
Diagnostic Errors
Kidney Calculi / radiography*,  ultrasonography*
Middle Aged
Retrospective Studies
Tomography, X-Ray Computed*
Comment In:
Urology. 2011 Jan;77(1):258-9; author reply 259   [PMID:  21195853 ]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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