Postnatal management of antenatal hydronephrosis 1

Licensed to Dr.SALIM ALATWANE
2007 UpToDate


Postnatal management of antenatal hydronephrosis

Laurence Baskin, MD


INTRODUCTION — Fetal hydronephrosis (dilatation of the renal pelvis) collecting system) is a common, readily diagnosed finding on antenatal ultrasound examination and can be detected as early as the 12th to 14th week of gestation [ 1,2].

Although renal pelvic dilatation is a transient, physiologic state in most cases, urinary tract obstruction and vesicoureteral reflux (VUR) are also causal. These conditions can prevent normal renal development and/or cause renal injury. However, the majority of cases of antenatal hydronephrosis are not clinically significant and can lead to unnecessary testing of the newborn baby and anxiety for patients and healthcare providers.

OVERVIEW OF MANAGEMENT — The goal of postnatal management of infants with antenatal hydronephrosis is to identify those with significant congenital anomalies of the kidney and urinary tract (CAKUT) while avoiding unnecessary testing in patients with physiologic or clinically insignificant hydronephrosis. In addition, early identification of infants with significant disease allows initiation of interventional therapy that minimizes adverse effects of CAKUT.

Evaluation includes physical examination and the use of radiologic studies to detect renal and urinary tract abnormalities including obstructive uropathy or vesicoureteral reflux (VUR).

PHYSICAL EXAMINATION — The physical examination of the newborn can detect abnormalities that suggest genitourinary abnormalities associated with antenatal hydronephrosis. These include the following:

· The presence of an abdominal mass that could represent an enlarged kidney due to obstructive uropathy or multicystic dysplastic kidney (MCDK).

· A palpable bladder in a male infant, especially after voiding, may suggest posterior urethral valves.

· A male infant with prune belly syndrome will have deficient abdominal wall musculature and undescended testes. The presence of associated anomalies should be noted.

· The presence of outer ear abnormalities are associated with an increased risk of congenital anomalies of the kidney and urinary tract (CAKUT).

· A single umbilical artery is associated with an increased risk of CAKUT, particularly vesicoureteral reflux.

RADIOLOGIC STUDIES —

Ultrasonography —

Affected infants should have an ultrasound examination of the kidneys and bladder in the postnatal period. The timing of the study depends upon the severity of the antenatal hydronephrosis. In general, examination should be avoided in the first two days after birth because hydronephrosis may not be detected because of physiologic volume depletion and relative oliguria. However, infants with bilateral hydronephrosis and those with a severe hydronephrotic solitary kidney require urgent evaluation on the first postnatal day because of the increased likelihood of significant disease.

Voiding cystourethogram — A voiding cystourethogram (VCUG) is performed to detect VUR and in boys, to evaluate the posterior urethra.

Diuretic renography — Diuretic renography (renal scan and the administration of a diuretic) is used to diagnose urinary tract obstruction in infants with persistent hydronephrosis, usually ordered after a VCUG has demonstrated no vesicoureteral reflux [ 4]. It measures the drainage time from the renal pelvis and assesses total and each individual kidney's renal function.

Intravenous urogram — The combination of renal ultrasound and diuretic renography has replaced the intravenous urogram (IVU) as a technique to evaluate renal anatomy and function in infants. This technique requires the use of ionizing radiation and rarely reveals any additional useful information in asymptomatic patients.

to be continue ..