Is fluid ingestion really necessary during ultrasonography for detecting ureteral stones? A prospective randomized study

Abstract

Objective. Ultrasonographic evaluation of ureteral stones is usually performed after fluid ingestion for filling the bladder to visualize the ureterovesical junction better. We hypothesized that water ingestion may decrease the imaging quality of ultrasonography for detecting ureter stones. In our prospective randomized study, the accuracy of ultrasonography for detecting ureteral stones performed with or without fluid intake were evaluated. Methods. The study population comprised 150 consecutive patients thought to have ureteral stones who underwent ultrasonography. Patients were divided into 2 groups. Group A patients ingested 500 ml_ of water to distend the bladder before ultrasonographic examination. Group B patients were restricted from drinking any water at least 4 hours before the procedure. Results. Ultrasonography showed 35 (67.30%) of 52 stones in group A and 68 (93.15%) of 73 stones in group B. The difference of detection rates between the 2 groups was statistically significant (P < .001). The greatest improvement in detection rates was noted in the middle ureter stones. The evaluated sensitivity and specificity rates for group A were 67% and 82%, respectively, and those for group B were 93% and 94%. When the 2 methods were compared, total accuracy of ultra-sonography increased from 71% in group A to 93% in group B. Conclusions. This prospective randomized study showed that the diagnostic accuracy of ultrasonography for detection of middle ureteral stones increased significantly when performed without any water ingestion before the procedure. We recommend that patients thought to have ureteral stones should be first examined without any fluid ingestion. © 2005 by the American Institute of Ultrasound in Medicine.