Assessment of the renal collecting system using a pocket-sized ultrasound device

Abstract

Purpose

To assess the performance of a pocket-sized ultrasound device (PUD) for evaluating dilatation of the renal collecting system with high-end ultrasound devices (HUDs) as a reference standard.

Methods

One sonographer examined both kidneys using a PUD to evaluate dilatation of the collecting system. The grading of the dilatation ranged from 0 to 4. Immediately after the examination, another sonographer blinded to the previous results performed a formal examination with a HUD.

Results

Two hundred kidneys in 100 patients were included in the analysis. The agreement of grades between the PUD and HUDs was excellent (weighted kappa = 0.83; P < 0.001). When hydronephrosis was defined as grade 1 or higher, the test characteristics of the PUD were as follows: sensitivity 91% (95% confidence interval (CI) 79–97%), positive predictive value 73% (95% CI 60–83%), and negative predictive value 96% (95% CI 92–99%). When hydronephrosis was defined as grade 2 or higher, the test characteristics were as follows: sensitivity 88% (95% CI 73–97%), positive predictive value 75% (95% CI 59–87%), and negative predictive value 98% (95% CI 94–99%).

Conclusion

Ultrasound using a PUD is useful for evaluating dilatation of the collecting system, especially for ruling out its presence.