Bilateral Hydronephrosis

Bilateral Hydronephrosis
Sara M. O’Hara, MD, FAAP
DIFFERENTIAL DIAGNOSIS
Common
  • Vesicoureteral Reflux (VUR)
  • Posterior Urethral Valves
  • Neurogenic Bladder
Less Common
  • Megaureter
  • Crossed Fused Ectopia
  • Horseshoe Kidney
  • Megacystis Megaureter
  • Bladder Outlet Obstruction
    • Cecoureterocele
    • Bladder Rhabdomyosarcoma
    • Pelvic Mass with Compression
    • Cloacal and Anorectal Malformations
Rare but Important
  • Prune Belly
  • Urethral Duplication
  • Anterior Urethral Valves
  • Megacalycosis
ESSENTIAL INFORMATION
Key Differential Diagnosis Issues
  • Some potential diagnoses may occur unilaterally or bilaterally
  • Severe cases typically noted on prenatal imaging and further evaluated in newborn
  • Clinical history and associated anomalies narrow differential
Helpful Clues for Common Diagnoses
  • Vesicoureteral Reflux (VUR)
    • Retrograde flow of urine from bladder toward kidneys
    • Graded from 1 (mild) to 5 (severe)
    • 80% of children outgrow reflux by puberty
    • Associated infection and renal scarring
    • Imaging: Voiding cystourethrography (VCUG), nuclear cystogram, sonocystogram (if US contrast available)
  • Posterior Urethral Valves
    • Congenital condition found only in boys
    • Persistent or prominent plicae colliculi in urethra causes variable degree of obstruction
    • Unilateral VUR or urinoma decompresses system, protective of contralateral kidney
      • Better long-term prognosis
    • Degree of obstruction varies
      • Severe: Usually diagnosed in fetus/newborn with oligohydramnios, respiratory, and renal insufficiency
      • Mild: May go undetected for years; late symptoms include renal failure and bladder dysfunction
    • Imaging: VCUG
      • Shows valve tissue &/or urethral caliber change
    • Treatment: Endoscopic valve ablation
  • Neurogenic Bladder
    • Malfunctioning bladder from any neurologic disorder
    • Upper tract compromised by
      • Poor bladder emptying and VUR
      • Urinary tract infections
      • Elevated bladder pressures
    • Highly compliant bladder in infancy common
      • Huge bladder capacity, poor emptying
    • Gradually develops muscular hypertrophy, which decreases compliance and capacity
    • End stage: Low capacity, noncompliant, noncontractile bladder
    • Imaging: VCUG, US, CT, MR
      • Shows bladder wall trabeculation, VUR, diverticula, capacity, emptying
    • Urodynamics very important to monitor
    • Treatment
      • Medications to improve bladder compliance
      • Catheterization to simulate normal bladder distention and emptying
Helpful Clues for Less Common Diagnoses
  • Megaureter
    • a.k.a. primary megaureter
    • Focal concentric narrowing of extravesical distal ureter 1-3 cm in length
    • Unknown etiology but theorized to be
      • Paucity of ganglion cells or
      • Hypoplasia/atrophy of muscle fibers in distal ureteral segment
    • Refluxing and nonrefluxing varieties
    • Imaging: Diuretic renogram, US, VCUG, MR urography
    • Treatment
      • Resection of narrowed segment and re-implantation
    • Crossed Fused Ectopia
      • Results from abnormal migration of kidney in utero
      • Upper kidney is orthotopic; other kidney is on wrong side and in low position
      • Lower pole of orthotopic kidney fused to upper pole of ectopic kidney
      • Ureter from lower kidney crosses to contralateral trigone
      • Associated aberrant and accessory vessels
      • Hydroureteronephrosis may be segmental or involve whole kidney
      • Imaging: Diuretic renogram, US, VCUG, MR urography
    • Horseshoe Kidney
      • Results from abnormal migration of kidney in utero
      • Lower poles of kidney fused in midline
      • Upper poles are lower than usual
      • Aberrant and accessory vessels and ureters common
      • Hydroureteronephrosis may be segmental or involve whole kidney
      • Imaging: Diuretic renogram, US, VCUG, MR urography
    • Megacystis Megaureter
      • Large, thin-walled, smooth bladder from constant recycling of refluxed urine
      • Bladder contracts normally but never empties completely due to reflux
      • Bladder capacity and function normalize when VUR is corrected
      • Imaging: VCUG
    • Bladder Outlet Obstruction
      • Any cause of bladder outlet obstruction can lead to bilateral hydroureteronephrosis
      • Cecoureterocele
        • Prolapsed ureterocele
      • Bladder Rhabdomyosarcoma
        • Typically large with significant mass effect
      • Pelvic Mass with Compression
        • Sacrococcygeal teratoma, Burkitt, etc.
      • Cloacal and Anorectal Malformations
      • Look for associated genital anomalies, hematometrocolpos
Helpful Clues for Rare Diagnoses
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Aug 10, 2016 | Posted by in PEDIATRICS | Comments Off on Bilateral Hydronephrosis

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