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The obstructed infected kidney and urosepsis
An obstructed kidney with infection is a urological emergency: start broad-spectrum antibiotics and drain urgently with a JJ stent or a percutaneous nephrostomy, and defer treatment of the stone itself until the infection has cleared.
Why it matters in the exam
The exam shows a patient with flank pain, fever, rigors and sometimes low blood pressure, and imaging with a ureteral stone and hydronephrosis. The question checks two things: that the next step is drainage (source control) and not stone fragmentation, and that a stent and a nephrostomy are equally effective. Lithotripsy or ureteroscopy during sepsis raises intrarenal pressure and worsens bacteraemia. A urine culture is taken before antibiotics, and if possible also from the urine above the obstruction during drainage, because it may differ from the bladder urine culture.
Further indications for urgent drainage in renal colic: obstruction of a solitary kidney or bilateral obstruction, acute kidney injury or anuria, and pain that cannot be controlled. The choice between the routes depends on the patient: a stent is preferred with a bleeding disorder or when percutaneous puncture is difficult, and a nephrostomy is preferred when a stent cannot be passed, when the patient cannot undergo anaesthesia, or with a large impacted stone. After drainage of bilateral obstruction a post-obstructive diuresis may follow, which needs fluid and electrolyte monitoring.
A patient who is septic by qSOFA (at least 2 of: respiratory rate 22 or more, altered mental state, systolic blood pressure 100 or less) gets fluids, blood cultures and antibiotics within one hour. The antibiotic choice takes the risk of ESBL into account: previous admission, previous antibiotics, a catheter or a prostate biopsy. Beyond the obstructed kidney, an abscess, emphysematous pyelonephritis and papillary necrosis are also sources of urosepsis. In older, diabetic and immunosuppressed patients fever may be low or absent, so confusion, falling blood pressure or a rising lactate in a patient with a known stone must raise the possibility of an obstructed infected kidney even without typical pain.
Key points
- Obstruction with infection — an emergency.
- Drainage by stent or nephrostomy, both effective.
- Antibiotics within one hour in sepsis.
- Stone treatment is deferred until the infection has cleared.
- Fever persisting beyond 72 hours — CT.
Summary table
| Situation | Action | Note |
|---|---|---|
| Obstructing stone with fever | Urgent drainage and antibiotics | Lithotripsy is deferred |
| Bleeding disorder | JJ stent | Avoids bleeding from a puncture |
| Stent failed or patient unfit for anaesthesia | Nephrostomy under local anaesthesia | External drainage is also possible |
| Obstructed solitary kidney or anuria | Urgent drainage | Even without fever |
| After bilateral drainage | Urine output and electrolyte monitoring | Post-obstructive diuresis |
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Sources
- EAU Guidelines on Urolithiasis, 2025 edition — Management of sepsis and anuria in the obstructed kidney
- EAU Guidelines on Urological Infections, 2025 edition — Urosepsis
- Surviving Sepsis Campaign: International Guidelines for Management of Sepsis and Septic Shock, 2021 — Source control and antimicrobial therapy
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.