Significanse of Renal Ultrasonography and MAG3 (Technetium-99m-Mercaptoacetyltriglycerine) Scan in Hydronephrosis during Infancy

Lee, So Young; Kim, Kun Suk; Moon, Dae Hyuk; Yoon, Chong Hyun; Park, Young Seo

Abstract

A prospective study had been performed in infants with hydronephrosis due to ureteropelvic junction stenosis to determine adequate management plan. Forty infants (47 renal units) were selected for the study during the period from January 1995 to July 1997 in the Department of Pediatrics, Asan Medical Center. They were diagnosed prenatally or early postnatally (<3 months of age) on the basis of renal ultrasonography and techotium-99m-mercap- toacetyltriglycerine (MAG3) scan. The antero-poste- rior pelvic diameter (APPD) was measured from serial renal ultrasonography and relative renal function and clearance half time (T1/2) were calculated from serial MAG3 scan. Those who had accompanying other urogenital anomalies or vesicoureteral reflux were excluded in this study. Follow-up tests (ultrasonography and MAG3 scan) and surgical corrections, if necessary, were performed according to the predetermined algorithrn. The male to female ratio was 3: 1. Hydronephrosis was involved the left side in 24 renal units, the right side in 9 renal units, and the bilateral sides in 14 renal units. All the hydronephrotic renal units were divided into 2 groups; Group A (19 renal units) those had taken surgical correction, and group B (28 renal units) those revealed spontaneous improvement without surgical correction. The mean follow-up duration was 7.2+/-6.3 months in group A and 14.1+/-12.6 months in group B. The mean APPD in the first postnatal renal ultrasonography was 19.4+6.8 mm in group A and 10.0+/-3.0mm in group B and this was statistically significant (P<0.01). The rela- tive renal function of group A in the first MAG3 scan was under 35% in 7 renal units and over 35M in 12 renal units. In group B, the relative renal function was over 35% in the all 28 renal units. Tl/2 in the first MAG3 scan was longer than 20 minutes in the all 19 renal units in group A. In group B, Tl/2 was shorter than 10 minutes in 15 renal units, between 10 minutes and 20 minutes in 6 renal units, and longer than 20 rninutes in 7 renal units. The mean APPD of the 7 renal units in group B of which Tl/2 was longer than 20 minutes was 12.62.6mm and that of group A was 19.4+/-6.8mrn and this was statistically significant (P<0.01). In conclusion, the renal ultrasonography and MAG3 scan can be used effectively to determine the degree of the stenosis of the ureteropelvic junction in hydronephosis during infancy. When the babies are diagnosed with hydronephrosis due to ureteropelvic junction stenosis in the early infantile period, serial renal ultrasonography and MAG3 scan play an important role in the decision of the management.