Urolithiasis: how accurate are plain radiographs?
OBJECTIVE
To determine the value of the kidneys, ureters, and bladder radiograph (KUB) in the diagnosis of urolithiasis using unenhanced helical computerized tomography (UHCT) as the gold standard.


METHODS
A retrospective study was performed on 100 consecutive patients being investigated for suspected urolithiasis. All patients presented with acute renal colic and had a KUB and UHCT within a 3-hour period. UHCT and KUB pairs were assessed separately by 2 radiologists in consensus who were blinded to the clinical details of the patients and the results of the other tests and examinations. The presence, location, number, and size of stones were recorded. Each UHCT and KUB pair was then compared for concordance on a stone-by-stone basis.


RESULTS
KUB was concordant with the gold standard UHCT in only 50% of patients (11 positive, 39 negative), giving a sensitivity of 18.6%, a specificity of 95.1%, a positive predictive value of 84.6%, and a negative predictive value of 44.8%.


CONCLUSIONS
KUB has a very low sensitivity for the detection of urolithiasis, although specificity is acceptable.
Chan
V O
VO
Department of Radiology, The Adelaide and Meath Hospital, Tallaght, Dublin, Ireland.
Buckley
O
O
Persaud
T
T
Torreggiani
W C
WC
D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003085:Colic / Q000175:diagnosis; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007674:Kidney Diseases / Q000175:diagnosis; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012015:Reference Standards; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D036542:Tomography, Spiral Computed / Q000379:methods*; D014567:Urography / Q000379:methods*; D052878:Urolithiasis / Q000175:diagnosis* / Q000000981:diagnostic imaging