Pyonephrosis
Pyonephrosis is pus in an obstructed collecting system — an infected, obstructed kidney that is a true urological emergency requiring urgent decompression plus antibiotics, never antibiotics alone or delayed definitive surgery.
The big picture
Pyonephrosis is suppurative infection of a hydronephrotic, obstructed kidney — the collecting system is full of pus. It usually arises behind an obstructing stone or stricture and presents as an infected obstructed system: fever, loin pain and sepsis, sometimes with a poorly functioning kidney.
Pyonephrosis = pus + obstruction = emergency: decompress now (nephrostomy preferred for pus) with antibiotics and resuscitation; treat the cause later.
Red flags
Pyonephrosis until proven otherwise — emergency decompression and antibiotics.
Confirm the drain is correctly placed and patent.
Resuscitate and decompress immediately; do not delay for definitive surgery.
Mechanism pathway
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Diagnostic algorithm
Each step answers one question. Tap to expand.
Treatment ladder
Urgent decompression plus antibiotics and resuscitation; defer definitive treatment of the cause until stable.
Complications
- Septic shock, multi-organ failure
- Renal destruction/loss
- Perinephric extension/abscess
- Nephrostomy bleeding/malposition
- Stent failure to drain pus
- Early decompression; choose nephrostomy for pus; confirm drainage
- Re-drain; organ support; nephrectomy if destroyed
If treatment fails
If sepsis persists after 'decompression', ask first: is the drain correctly placed and draining the pus?
Memory hooks
Pyonephrosis = pus + obstruction.
Emergency: decompress now.
Nephrostomy beats a stent for thick pus.
Antibiotics can't fix pus under pressure.
Treat the cause later.
Board traps
Infected obstruction with pus → drain first, treat cause later.
Thick pus → nephrostomy, not stent.
Persistent sepsis → drain not working.
Clinical cases
A diabetic woman with an obstructing ureteric stone has rigors, loin pain and hypotension; ultrasound shows hydronephrosis with internal echoes (pus).
What is the diagnosis and immediate management?