Investigation of acute flank pain associated with hematuria has traditionally included an excretory urogram to exclude or detect calculi. However, this study has a number of contraindications, including significant renal insufficiency, dehydration, past reaction to contrast agents and pregnancy. To find a safe, noninvasive alternative to excretory urography, Sinclair and colleagues studied the accuracy of ultrasonography in the diagnosis of ureteral obstruction by calculi.
In a prospective study, 98 patients presenting with renal colic or hematuria, or both, were evaluated by means of ultrasonography and excretory urography. The two radiologists who reported on the procedures were blinded to the results of the other diagnostic test and the ultimate clinical outcome. The diagnosis of urinary calculus was made only by identification of calculi at surgery or by reported passage of a stone by the patient.
Eighty-five of the patients (56 men and 29 women) were available for follow-up study. The mean age of the patients was 40.5 years; they ranged from 18 to 77 years of age. Calculi were identified in 69 patients (81 percent). Ultrasonography demonstrated calculi in 44 patients (sensitivity: 64 percent; specificity: 100 percent). Excretory urography demonstrated calculi in 44 patients (sensitivity and specificity identical to ultrasonography). When the presence of obstructive hydronephrosis only was used to diagnose renal calculi, ultrasonography identified 59 of the patients with stones (sensitivity: 85 percent; specificity: 100 percent) and excretory urography identified 62 of the patients (sensitivity: 90 percent; specificity: 94 percent). When the results of both diagnostic techniques were combined, calculi were identified in 59 patients (sensitivity: 85 percent; specificity: 100 percent), and hydronephrosis was seen in 66 patients (sensitivity: 95 percent; specificity: 94 percent).
The data suggest that excretory urography and ultrasonography are equally reliable in the detection of renal calculi. Currently, excretory urography remains the investigation of choice because of its availability and ease of interpretation. In selected patients, the use of both procedures may improve diagnostic accuracy. (Annals of Emergency Medicine, May 1989, vol. 18, p. 556.)
COPYRIGHT 1990 American Academy of Family Physicians
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