Postnatal management of antenatally detected hydronephrosis

Table 1 Differential diagnosis of prenatal hydronephrosis

Etiology	Incidence
Transient/physiologic	50%-70%
PUJ obstruction	10%-30%
Vesicoureteral reflux	10%-40%
Ureterovesical junction obstruction	5%-15%
Multicystic dysplastic kidney	2%-5%
Posterior urethral valves	1%-5%
Ureterocele	1%-5%
Others like ectopic ureter, etc.	< 1%

PUJ: Pelviureteric junction.

Table 2 Descriptive definition of hydronephrosis by Antero Posterior Diameter

Classification ofhydronephrosis	Second trimesterAPD in mm	Third trimesterAPD in mm
Mild	4-7	7-9
Moderate	7-10	9-15
Severe	> 10	> 15

APD: Antero posterior diameter.

Table 3 Society of fetal urology grading of hydronephrosis

Grade 1	Urine barely splits the sinus
Grade 2	Moderate renal pelvis splitting confined to renal border with dilated major calyces
Grade 3	Pelvis distended outside the renal border, major and minor calyces are dilated; the parenchyma is spared
Grade 4	Parenchyma is thinned

Table 4 Measures to be taken within first 48 h after birth in infants diagnosed with antenatal hydronephrosis

USG	Suspected lower tract obstruction, e.g., Posterior urethral valves, prune belly syndrome
	Bilateral hydronephrosis with or without hydroureter
	Solitary kidney with APD > 15 mm or SFU grade 2 or more
Antibiotic	Suspected lower tract obstruction
prophylaxis	APD > 10 mm or SFU grade 2 or more in the third trimester
	Solitary kidney with hydronephrosis of any grade
	Bilateral hydronephrosis
VCUG	Suspected posterior urethral valves antenatally
Catheterization	Suspected lower tract obstruction-posterior urethral valve or prune belly syndrome

VCUG: Voiding cysto urethrogram; APD: Antero Posterior Diameter; SFU: Society of Fetal Urology; USG: Ultrasonography.

Table 5 Management recommendations in neonates with antenatal hydronephrosis but Normal Post natal ultrasound

USG	At 1 mo and at 3-6 mo
VCUG	Not recommended if two USG are normal
Antibiotic prophylaxis	Not recommended routinely Would be prudent to be started if the follow up is not reliable For those not getting prophylaxis, parents should be told to get a urine routine if the neonate shows any signs of not being well

VCUG: Voiding cysto urethrogram; USG: Ultrasonography.

Table 6 Categorization of patients with unilateral hydronephrosis with no hydroureter into mild, moderate and severe hydronephrosis based on Antero Posterior Diameter /Society of Fetal Urology Grading

	Mild	Moderate	Severe
APD	< 20 mm	20-30 mm	> 30 mm
SFU	Grade 1 and 2	Grade 3	Grade 4

APD: Antero posterior diameter; SFU: Society of Fetal Urology.