II. Epidemiology

  1. Accounts for 1-10% of Acute Renal Failure cases
  2. More common in elderly

III. Pathophysiology

  1. Urinary Tract Obstruction
  2. Results in renal Pelvis dilatation
  3. Progressive decrease in Renal Function
    1. Increased intratubular pressure
    2. Decreased capillary filtration pressure

V. Symptoms

  1. Abdomen or Groin Pain (colic-type attacks)

VI. Signs

  1. Mass at flank, suprapubic, or central Abdomen
  2. Abdominal exam
  3. Pelvic exam
  4. Rectal Exam
  5. Anuria (Indicates obstruction in 90% cases)

VII. Labs

  1. See Renal Function
  2. Urine Sediment
    1. Normal sediment
    2. Hematuria
    3. Pyuria
    4. Crystals

VIII. Diagnostic Testing

  1. Post-void residual >100 ml
    1. Indicates Bladder outlet obstruction
  2. Ultrasound or Intravenous Pyelogram
    1. Dilated ureters or renal Pelvis
  3. Abdominal CT or Abdominal MRI
  4. Percutaneous Nephrostomy drainage trial

IX. Management

  1. See Acute Kidney Injury Management
  2. Exclude reversible causes rapidly
  3. Renal Function recovery reflects obstruction duration

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