Acute upper urinary tract obstruction

Definition

Acute upper urinary tract obstruction is impaired urine drainage at the renal pelvis or ureter, with a risk of increased intrapelvic pressure, infection, and loss of kidney function.

Causes: stone, blood clot, tumor, stricture, external compression, retroperitoneal fibrosis, iatrogenic injury.

Clinical assessment

Key findings are pain, hydronephrosis, reduced urine output, rising creatinine, and signs of infection.

Anuria is particularly dangerous in bilateral obstruction or a solitary functioning kidney.

Diagnosis

• Ultrasonography provides a rapid assessment of collecting system dilatation.
• Noncontrast CT is optimal for stones; extend the imaging workup if a tumor or trauma is suspected.
• Laboratory tests: creatinine, electrolytes, CBC, urinalysis, and culture if infection is suspected (without delaying treatment).

Acute obstruction without infection

Management depends on:

• the level and cause of obstruction;
• the condition of the kidney;
• symptom severity;
• the likelihood of spontaneous resolution.

Persistent obstruction, deteriorating function, intractable pain, or inability to observe safely requires active restoration of drainage.

Obstruction with infection (a urological emergency)

• Treat the systemic infection and urgently restore urinary drainage in parallel.
• Drainage: retrograde ureteral stent or percutaneous nephrostomy.
• The choice depends on anatomy, the level of obstruction, illness severity, and equipment availability.
• Defer definitive stone removal until the infection is controlled.

Stent or nephrostomy?

The decision must reflect the clinical situation rather than a universal preference for one method.

After drainage

• Monitor temperature, hemodynamics, urine output, and creatinine.
• Culture urine from the drained system as indicated.
• After clinical improvement, establish the underlying cause and plan definitive treatment.

Algorithm