Hydronephrosis

Hydronephrosis

Aseptic dilatation of kidneys due to obstruction.


Aetiology

Unilateral hydronephrosis:

  • IDIOPATHIC pelviureteric junction obstruction (M/C)
  • EXTRAMURAL OBSTRUCTION
    • Tumour
      • From adjacent structures (Cervix, prostate, rectum, colo or caecum)
    • Idiopathic retroperitoneal fibrosis
    • Retrocaval/circumcaval ureter
  • INTRAMURAL OBSTRUCTION
    • Congenital stenosis
    • Ureterocele & congenital small ureteric orifice
    • Inflammatory stricture
      • Following removal of ureteric calculus or repair of damaged ureter
      • Due to tuberculous infection
    • Neoplasm
      • Ureter cancer
      • Bladder cancer involving ureter
  • INTRALUMINAL OBSTRUCTION
    • Calculus in pelvis/ureter
    • Sloughed papilla
      • In papillary necrosis (esp. in DM, analgesic abuse, sickle cell anaemia)

Bilateral hydronephrosis:

  • LOWER URINARY TRACT OBSTRUCTION
    • Congenital:
      • Posterior urethral valves
      • Urethral atresia
    • Acquired:
      • Benign prostatic enlargement or carcinoma of prostate
      • Postoperative bladder neck scarring
      • Urethral Stricture
      • Phimosis
  • Bilateral UPPER URINARY TRACT OBSTRUCTION
    • Idiopathic retroperitoneal fibrosis
    • Idiopathic pelviureteric junction obstruction
  • PREGNANCY
    • Effects on ureteric smooth muscle due to high levels of progesterone 

Pathophysiology

  • Severe long-standing hydronephrosis → Nephron destruction → Increased serum creatinine & electrolyte imbalance
  • Blockade → Dilated ureter & renal pelvis + medullary & cortical thinning
  • KIDNEY
    • Calyceal dilatation + pressure atrophy
    • Thin-walled, lobulated, fluid-filled sac

Clinical features

Unilateral hydronephrosis:

  • Asymptomatic
  • Mild pain/dull aching in loin
    • Dragging heaviness worsened by excess fluid intake
  • Palpable kidney
  • Dietl’s crisis: Intermittent hydronephrosis (loin swelling) + acute renal pain
    • Pain & swelling goes away as large volume of urine is passed
  • Antenatal detection
    • By USG

Bilateral hydronephrosis:

Symptoms of bladder outflow obstruction predominate
  • Impalpable kidneys: As renal failure intervenes before enlargement

Complications

  • UTI
  • Postrenal Azotemia

Diagnosis

Imaging:

  • Foetuses/infants
    • Prenatal ultrasound
  • Intravenous Urography (IVU) or Pyelography
  • Isotope renography: Best imaging modality
    • MAG3 scan: Best for assessing renal function
    • DMSA scan: Best for assessing scarring
  • CT Scan

The Society of Foetal Ultrasound Grading:

hydronephrosis
Children’s C. Hydronephrosis – CHOC Children’s [Internet]. CHOC Children’s. 2017 [cited 26 March 2017]. Available from: http://www.choc.org/programs-services/urology/hydronephrosis/
  • Grade 0 – no dilation with calyceal walls apposed
  • Grade 1 (mild) – dilation of the renal pelvis without dilation of the calyces nor parenchymal atrophy
  • Grade 2 (mild) – dilation of the renal pelvis and calyces without parenchymal atrophy
  • Grade 3 (moderate) – moderate dilation of the renal pelvis and calyces with blunting of the fornices and flattening of papillae
  • Grade 4 (severe) – gross dilation/ballooning of the renal pelvis and calyces with loss of borders between the renal pelvis and calyces and renal atrophy seen as cortical thinning

Management

Mild cases:

  • Serial USG scans
  • Operate if dilatation increases

Moderate-severe cases:

  • Pyeloplasty (Anderson-Hynes operation)
    • Upper-third of ureter & renal pelvis anastomosis
      • Anastomosis protected by:
        • Nephrostomy tube
        • Ureteric stent
  • Endoscopic pyelolysis
    • Disruption of pelviureteric junction by a balloon passed up ureter under radiographic control

Destruction of kidney:

  • Nephrectomy

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