Infected hydronephrosis and pyonephrosis

Definition

• Infected hydronephrosis is dilatation of the renal collecting system with infected urine in the setting of impaired drainage.
• Pyonephrosis is the accumulation of pus in the kidney.

These are among the most dangerous forms of complicated upper urinary tract infection.

When to suspect it

• Fever and rigors in a patient with hydronephrosis.
• Severe pain, pyuria.
• Deteriorating kidney function or signs of sepsis.

Diagnosis

• Ultrasonography: hydronephrosis, heterogeneous contents.
• CT: level of obstruction, gas, abscess, stones, and extent of inflammation.
• Laboratory tests: CBC, creatinine, electrolytes, CRP, and lactate in severe illness.
• Urine and blood cultures as indicated.

Treatment

Main components:

1. Systemic antibacterial therapy (intravenous).
2. Organ support (fluid therapy, vasopressors).
3. Urgent source control through drainage (stent or nephrostomy).
4. In pyonephrosis, nephrostomy drainage followed by assessment of renal viability.
5. Definitive surgery after stabilization.

After stabilization

• Identify the cause of obstruction (stone, stricture, tumor).
• Plan definitive restoration of urinary drainage.
• Assess individual kidney function, especially in longstanding hydronephrosis.

Algorithm