Utility of ultrasound elastography in postoperative follow-up of children with unilateral ureteropelvic junction obstruction

INTRODUCTION: We aimed to determine whether shear wave velocity (SWV) on ultrasound elastography is useful in follow-up of children with ureteropelvic junction obstruction (UPJO) following pyeloplasty. METHODS: Consecutive children with unilateral UPJO who were co-operative for elastography (n = 31) were included. SWV of normal kidney was used as control, and it was compared with that of the affected kidney (UPJO) in the same patient. They were followed up with elastography at 3 months and elastography + renogram at 6 months postoperatively. In patients with a static renogram at 6 months, the study was repeated at 1 year. Patient outcomes were classified as improved at 6 months, static at 6 months, and worsened at 1 year based on ultrasound and renogram findings. The SWV was compared between the different outcomes. RESULTS: Thirty-one children with a median age of 8.5 years were studied (m:f = 29:2; L:R = 22:9). The mean SWV was significantly higher (3.21 m/s) in UPJO kidney compared to the SWV (2.72 m/s) found in normal kidney (P = 0.011). The mean SWV was significantly less at 3 months (2.73 m/s) and 6 months (2.57 m/s) postoperative follow-up (P = 0.018 and P= 0.001). Among the patients who improved, the mean SWV was 2.65 m/s. This SWV was significantly raised (3.57 m/s) in patients whose condition remained static (P = 0.006) and even higher (4.36 m/s) in those who worsened (P = 0.001). CONCLUSIONS: SWV was significantly higher in UPJO compared to normal kidneys in children. It is useful in assessing postoperative resolution, and a rising velocity can be useful as an early marker of recurrence in UPJO.