Acute Pyelonephritis
Pyelonephritis is infection of the kidney itself — the make-or-break question is whether it is obstructed, because an obstructed infected kidney must be drained.
The big picture
Bacteria ascend from the bladder (or seed via blood), invade the renal parenchyma, and trigger a systemic inflammatory response — fever, flank pain, and rigors. If urine cannot drain, pressure plus pus equals pyonephrosis and sepsis.
Failure to improve within 48–72 hours means image for obstruction or abscess and drain the source.
Mechanism pathway
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Symptom sorter
The common presentation.
Diagnostic algorithm
Each step answers one question. Tap to expand.
Treatment ladder
Resuscitate, give prompt culture-guided antibiotics, and relieve any obstruction urgently — drainage beats antibiotic escalation.
Procedure chooser
- Nephrectomy rarely, for emphysematous pyelonephritis failing drainage
Complications
- Sepsis
- Pyonephrosis
- Renal/perinephric abscess
- Emphysematous pyelonephritis
- Scarring/impaired function
- Stent/nephrostomy: discomfort, displacement
- Antibiotic adverse effects
- Drain obstruction early
- Image non-responders
- Control diabetes
- Urgent decompression for obstruction
- Percutaneous abscess drainage
- Intensive support for emphysematous disease
Red flags
Memory hooks
Fever + flank = kidney.
Not better in 48–72 h → image.
Obstructed + infected → drain.
Gas in a diabetic kidney = emphysematous.
Board traps
Persistent fever on appropriate antibiotics — image for abscess/obstruction.
Diabetic with sepsis and renal gas — emphysematous pyelonephritis, drainage.
Obstructing stone with fever — decompress.
Clinical cases
A woman with pyelonephritis remains febrile and tachycardic after 3 days of appropriate IV antibiotics.
What is the next step?