文本框: STUDY ON THE PREDICTIVE VALUE OF ANTENATAL AND POSTNATAL RENAL ULTRASONOGRAPHY IN CHINESE NEWBORN INFANTS Wong W1, Ma KC1, Hui J1, Wong N1, Lau TK2, Ng PC1, Cheung KL1, So KW1, Yeung CK3, Fok TF1 1Department of Paediatrics, 2Department of Obstetrics & Gynaecology, 3Department of Surgery, Prince of Wales Hospital (PWH), The Chinese University of Hong Kong, Hong Kong, China Objectives: To study the epidemiology of antenatally diagnosed hydronephrosis in Chinese newborns in Hong Kong, to assess the predictive value of antenatal and postnatal ultrasound and to define significant dilatation of urinary tract for postnatal management. Methods: All Chinese newborn infants born in PWH from August 1st, 1995 to 28th February 1999 who had an antenatal ultrasound finding of dilated renal pelvis of >5mm at or after 20th week of gestation were recruited. Infants with lethal congenital anomalies or of other ethnic groups were excluded. All studied infants would be scheduled to have ultrasonography, micturating cystourethrogram and MAG3 scan depending on their severity. Results: A total of 104 infants (81 male and 23 female) and 144 renal units (57 right and 87 left kidneys) were recruited. The incidence of antenatal dilated renal pelvis was 1.6%. The incidence of significant uropathy was 0.09% and all of them were asymptomatic at birth. 6 infants had pelvi-ureteric junction obstruction, 3 had vesicoureteric reflux, 2 had multicystic dysplastic kidneys, 1 had vesicoureteric junction obstruction and 7 had other miscellaneous lesions. For antenatal ultrasound scan, using 8mm as optimal pelvic AP diameter cut-off, the negative predictive value for excluding significant uropathy was 97.12%. Similarly, for postnatal scan, the negative predictive value was 96.36%. Conclusion: Chinese infants have similar incidence of renal dilatation but less incidence of significant dilatation when compared to published western data. We define hydronephrosis requiring further investigation such as MCU and isotope scan as AP diameter of renal pelvis >8mm in either antenatal or postnatal scan. 1925