A. Etiology

1. Chronic Urinary Tract Infection (UTI) leading to Fibrosis
2. Stones (Nephrolithiasis) ~85% can be seen on plain radiograph
3. Obstruction of ureter by mass
   1. Benign Prostatic Hyperplasia (BPH) is most common
   2. Neoplasm: metastatic, bladder and ovarian cancer
4. Retroperitoneal Fibrosis - may not show hydronephrosis on radiograph

B. Symptoms and Signs

1. Costoverbegral angle tenderness
2. Oliguria and Dysuria
3. Renal Atrophy (usually later stage)
4. Hydronephrosis of Kidney (enlargement, usually earlier stage)
5. Systemic Hypertension

C. Evaluation

1. Renal ultrasound - will detect changes in parenchymal kidneys, some masses
2. CT scan - usually with intravenous dye; detects masses well, overall anatomy
3. Intravenous pyelogram (IVP) - on patients with suspected stones
4. Full renal chemistry evaluation should be done
5. Urinalysis and culture should be done if possible

D. Treatment

1. Initial placement of Foley Catheter (may be traumatic)
   1. Allow diuresis to procede at natural rate without clamping catheter
   2. Some bleeding may occur initially due to 'fissuring" or bladder then decrease pressure
   3. There is NO demonstrated benefit to regulating the rate of diuresis
2. Fluids to prevent dehydration with post-obstructive Diuresis
   1. Most patients are initially fluid overloaded, ~3-6 liters
   2. Fluids should generally only be replaced for symptoms (orthostasis, tachycardia)
   3. Careful monitoring of sodium and particularly potassium is critical
   4. Magnesium levels should probably be measured as well
3. Renal function usually returns to close to baseline (depending on duration of obstruction)
4. Relieve Obstruction
   1. BPH is probably most common cause
   2. TURP is generally indicated for severe BPH
   3. Mild BPH can be observed, but if renal function is compromised, surgery usually used
   4. Medications also effective in mild to moderate BPH
   5. Ureteral shunt can be created surgically

References

1. Oesterling JE. 1995. NEJM. 332(2):99