Acute pyelonephritis and obstructive pyelonephritis

Definition

Acute pyelonephritis is an infectious inflammatory condition affecting the renal parenchyma and collecting system.

A crucial distinction: in emergency urology, distinguish systemic urinary tract infection from pyelonephritis complicated by impaired drainage. The latter requires relief of obstruction as well as antibiotics.

Clinical presentation

• Fever, rigors, lower back pain, weakness, nausea, dysuria.
• Severe disease: tachycardia, hypotension, confusion, oliguria, and signs of organ dysfunction.
• Classic symptoms may be absent in older and immunocompromised patients.

Diagnosis

• Urinalysis + culture with susceptibility testing.
• CBC, creatinine, electrolytes.
• Imaging (ultrasonography/CT) if obstruction is suspected.
• Blood cultures in sepsis (without delaying therapy).

Antibacterial therapy

• Select an empirical agent according to severity, previous cultures, local resistance patterns, allergies, kidney function, and ESBL risk.
• Use intravenous administration in severe illness.
• Once culture results are available, narrow treatment to the narrowest-spectrum active agent.
• A switch to oral therapy may be possible after clinical improvement.

Obstructive pyelonephritis

• Antibiotics without restoration of drainage may be insufficient.
• Urgent drainage is mandatory.
• Do not perform definitive lithotripsy during uncontrolled sepsis.

Assessing treatment response

• Track temperature, pain, hemodynamics, urine output, creatinine, and inflammatory markers.
• Persistent fever or deterioration → reassess the source, adequacy of drainage, and resistance; look for an abscess.

Algorithm