CT or IVU in the assessment of renal colic?

Objectives : This prospective study was designed to determine the reliabili ty of noncontrast spiral CT scan, compared to that of intravenous urography (IVU), in the diagnostic assessment of acute renewl colid. Material and Methods : 53 patients, admitted with an empirical diagnosis of renal colic after initial assessment, were included and underwent spiral C T scan without contrast agent injection, immediately followed by IVU, These examinations were performed according to a blind protocol by two different radiologists. We initially looked for the presence of stones and/or urinar y tract obstruction. Patients with a stone and/or obstruction (urinary trac t dilatation) visible on CT scan were then examined for the presence of CT signs associated,vith stone disease (infiltration of the perirenal and peri ureteric fat, oedema of the ureteric wall and loss of sinus fat). We calcul ated the statistical correlation better een the presence or absence of obst ruction mid these accessory signs. Results : 45 stones were recovered (in 36 cases before the two examinations ). 36 stones were identified on CT versus only 24 on urography. Urinary tra ct dilatation was demonstrated in 26 out of 53 cases by both urography and CT The frequency of accessory signs visible on CT in the presence of stones (n=36) was 66% for infiltration of periureteric fat, 36% for infiltration of perirenal fat and 75% for oedema of the ureteric wall. In the presence o f urinary tract dilatation, these frequencies were 92%, 84% and 60% respect ively Conclusion : Noncontrast spiral CT is a reliable and rapid diagnostic modal ity for the detection of urinary stones, providing a morphological study eq uivalent to that of IVU and able to guide appropriate treatment. It should replace IVU in the diagnostic assessment of renal colic.