Infected, Obstructed Kidney (Stone Emergency)
This is the one stone scenario that kills — an obstructing stone plus infection is a closed, infected space under pressure. The reflex: fever + obstruction = decompress immediately.
The big picture
This is the one stone scenario that kills, and the one where hesitation costs a kidney or a life. An obstructing stone plus infection behind it is a closed, infected space under pressure — pus that cannot drain, seeding the bloodstream. It is the urological equivalent of an abscess that must be drained now. The single most important reflex in stone disease is: fever + obstruction = decompress immediately.
The framework: recognise the combination (obstruction + infection/sepsis), understand why it's an emergency (undrainable infected collection → urosepsis), and act — decompress first, treat the stone later.
Mechanism pathway
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Diagnostic algorithm
Each step answers one question. Tap to expand.
Board traps
Fever + obstruction = emergency → decompress immediately (stent or nephrostomy). This is the master reflex.
Antibiotics alone are not enough — the infected urine behind the stone cannot drain without decompression.
Do NOT attempt definitive stone removal during active sepsis — drain first, treat the stone later.
Either a stent or a nephrostomy works; nephrostomy is often chosen for complex/multiple stones or the very unwell.
Pyonephrosis = pus under pressure — think of it as an abscess that must be drained.