The Value Of Doppler Ultrasound In The Evaluation Of Pediatric Hydronephrosis

Background and objective: Congenital hydronephrosis is the most common urological disease in pediatric surgery. Of all prenatal ultrasound studies nearly 1% show pelvic dilatation, during gestation and approximately 50% of dilatation cases persist till after birth. It is well accepted that urinary tract dilatation does not always indicate obstruction. In some of these cases, renal function deteriorates due to obstructive hydronephrosis, while others show no function loss with pelvic dilatation. No diagnostic tests have provided noninvasive method in the differentiation of nonobstructive from obstructive hydronephrosis till today. Although there were different methods in this field including B-mode ultrasound, intravenous urogram(IVU), renogram, computerized tomography(CT), magnetic resonance image(MRI). However, each of them has its limitation. Renal vascular resistance will increase in many pathologic conditions. Therefore, characterization of changed renal blood flow can be used to discriminate various pathophysiological conditions of kidney. With the improvement of ultrasonic technology, moreparameters are available in this field, such as resistive index(RI), pulsatality index(PI), resistive index ratio(RIR), parenchymal-to-pelvic area ratio. Obstruction of upper urinary tract leads to series of changes in kidney, such as increase of pelvic pressure, change of locally acting vasoactive factors, decrease of renal blood flow. These changes result in the increase of renal vascular resistance, which can be detected as an increase in the resistive index of the affected kidney. These parameters are widely used in adult group, while dispute arise when they are applied to pediatric group since neonate and infant are quite different from adult in many aspects. There were limited studies focusing on the different applications of RI according to different age group domestically, especially in the group younger than 7 years old. What's more, it is now accepted widely that RI is an age-dependent parameter, which decrease as children grow up. However, there is no similar study domestically yet. It is crucial to investigate the value of these parameters in evaluating renal function of pediatric hydronephrosis. The main objective of this thesis is to provide a reference value and assess the value of Doppler ultrasound in the evaluation of hydronephrosis by measuring renal blood flow parameters and renal parenchymal area in normal and hydronephrotic kidneys, investigating the changing trend of renal blood flow and parenchymal area, comparing the difference between normal kidneys and hydronephrotic ones and between obstructive hydronephrosis and nonobstructive ones.Materials and methods: One hundred and four healthy children and forty-three hydronephrptic children are included in this research. The healthy children are proved by physical examination, any individual with urinary, or cardiovascular disease are excluded. The mean age of healthy children is 6.04±3.08(range from 23d to 14y). All hydronephrotic patients are divided into two groups: obstructivehydronephrosis(OBH) and nonobstructive hydronephrosis(NOB). The former group includes thirty-three patients(male 26, female 7) from September 2001 to March 2003, whose mean age is 5.98± 4.24y(range from 2m~14y). 26 of them have unilateral hydronephrosis, 6 of them have bilateral hydronephrosis, 1 has solitary kidney(39 hydronephrotic kidneys in all). All of the patients satisfied one or more of the following criteria of traditional indices of obstruction: a. flank pain; b. hematuria; c. affected kidney developing no image in IVU; d. a stricture proved during or after operation. All of these patients are divided into four groups according to Society for Fetal Urology guidelines for grading hydronephrosis: Group I ,6 with grade 1 hydronephrosis; Group II, 8 with grade 2-3 hydronephrosis; Group III, 16 with grade 4 hydronephrosis; Group IV, 9 with grade 5 hydronephrosis. NOB includes 10 unilateral hydronephrotic patients(male 8, female 2, mean age 6.6±2.5y, ra...