Kumud P Mehta
Consultant Pediatrician & Pediatric Nephrologist, Jaslok Hospital & Research Centre, Bai Jerbai Wadia Hospital for children, Mumbai, India
First Created: 01/10/2001 


Hydronephrosis (HDN) is defined as the dilatation of the renal pelvis and calyceal system. Hydronephrosis can be unilateral or bilateral, obstructive or non-obstructive; congenital, or acquired. Hydronephrosis in fetus/newborn is increasingly recognized due to the widespread use of fetal ultrasound scanning, advanced USG equipment, and greater expertise. It is estimated that urinary tract dilatation in utero is identified in 1% all pregnancies but in the only 1/5th of these, the abnormality is significant. The best method of diagnosing HDN is by USG of kidneys ureters and urinary bladder so that the cause of HDN can be detected.

Common Causes of Hydronephrosis

  • Pelviureteric junction obstruction (PUJ obstruction)

  • Vesicoureteric reflux (VUR)

  • Vesicoureteric junction obstruction

  • Multicystic kidney

  • Posterior ureteric valves (PU valves) (can be bilateral)

  • Obstructive or non obstructive megaureters

  • Ureterocele

  • Neurogenic bladder

  • Prune belly syndrome

  • Urethral atresia

Acquired Hydronephrosis

Hydronephrosis can occur due to acquired causes like

  • Urolithiasis or stone disease,

  • Stricture of ureter due to tuberculosis or following urologic surgery.

The underlying cause should be treated, obstruction removed by ESWL or surgery. The kidney can be permanently damaged because of pus formation in an obstructed hydronephrotic kidney due to pyonephrosis.

Antenatal USG Evaluation Includes

  • Serial measurements of renal pelvic AP diameter every 4-6 weekly from 16th week onwards(>10 mm significant),

  • Dilation of calyces, ureters

  • Echogenicity of renal parenchyma

  • Contralateral kidney size, dilation

  • Bladder size and thickness

  • Emptying time; urine flow

  • Amniotic fluid volume (oligohydramnios means poor fetal renal function)

  • Posterior urethral dilation

Antenatal USG evaluation of HDN can detect the above-mentioned causes, which need confirmation postnatally by clinical evaluation, micturating cystourethrography (MCU), radionuclide Tc99DTPA, or MAG renal scan.

Postnatal Evaluation of Hydronephrosis

At birth:

Clinical examination to observe urinary stream (poor in PU valves), renal masses, distended bladder which is firm in PU valves, abdominal wall muscles, undescended testes (Prune belly syndrome). (In suspected PU valves - immediate catheterization is required to drain the urinary bladder and relieve back pressure).

USG, MCU, serum creatine/BUN (to be repeated after 6 weeks of relief of obstruction to evaluate the effect of obstruction on renal function).

Approach to Unilateral Hydronephrosis

  • If a unilateral hydronephrosis is detected, USG should be repeated after 3-7 days when dilatation becomes more evident.
  • If ureter is dilated - MCU should be done to detect VUR.
  • If ureter is not seen- Tc99DTPA renal scan with diuretic renography should be done to detect PUJ obstruction and its severity so that surgery is planned.

Approach to Bilateral Mild to Moderate HDN

Same as above + S.creatine/BUN to diagnose renal insufficiency

Aims of systematic evaluation of hydronephrosis is to detect obstructive lesions which may require surgery in asymptomatic stage to prevent progressive renal damage for e.g.

  • Recurrent UTI leading to reflux nephropathy and CRF;

  • Obstructive nephropathy leading to CRF/ESRD, hypertension, growth failure, anemia and urolithiasis.

Indications of Surgery In HDN

PUJ obstruction

At initial diagnosis:

* Symptomatic HDN (UTI, renal mass, growth failure),

* Solitary kidney with impaired function,

* Bilateral severe HDN

* Relative renal function of obstructive kidney <30%.

On follow up:

* 10% decline in relative renal function on DTPA renal scan when repeated after 6-12 weeks

* Increasing HDN

* Post urethral valves, ureteroceles

* VUR Grade IV-V persisting beyond infancy

* New renal scars or recurrent UTI despite antibiotic prophylaxis

Management of Hydronephrosis

In asymptomatic HDN or HDN which is mild to moderate and stable after USG within 3-7 days, with no obstruction (Hydronephrosis due to ?VUR)

  • Antibiotic prophylaxis (amoxycillin/cephalexin for 3 months and then oral cotrimoxazole/nitrofurantoin single night dose for 6 months - 2 years to prevent UTI.

  • Urine cultures may be necessary if fever occurs.

  • Diuretic renography, MCU are recommended at 1-2 months after antibiotics

  • USG after a year.

If VUR is detected,

  • DMSA renal scan to detect renal scars

  • Surgery may needed if scars are present or there is presence of Grade IV-V VUR.

  • Repeat MCU/diuretic venography at 2 years to decide about resolution of VUR.

  • DMSA renal scan should be done every 2-3 yearly if scars are persistent or to detect presence of new scars.

  • BP; growth monitoring; S. Creatine/BUN, USG should be done yearly till 15-20 years.

Hydronephrosis Hydronephrosis https://www.pediatriconcall.com/show_article/default.aspx?main_cat=pediatric-nephrology&sub_cat=hydronephrosis&url=hydronephrosis-introduction 2001-01-10
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