Kidney and ureteric stones can be associated with urinary infections. Stones can harbour bacteria within them, making infections difficult to clear with antibiotics alone. Conversely, certain bacteria actively promote stone formation, creating a self-perpetuating cycle of stone growth and recurrent infection.
When a stone blocks the kidney drainage and infection is present behind the blockage, the kidney becomes a closed, infected space.
This condition is a true urological emergency. Without rapid drainage, the infection can spill into the bloodstream, causing sepsis, a life-threatening infection.
Understanding the warning signs and knowing when to seek emergency help is critical. An infected obstructed kidney will not respond to antibiotics alone — the kidney must be drained urgently.
Types of Infection
Types of Stone-Related Infections
Stone-related infections range from simple urinary tract infections to life-threatening sepsis. Understanding the spectrum helps recognise when urgent intervention is needed.
Moderate
UTI with Coexisting Stone
A urinary tract infection occurring alongside a kidney or ureteric stone. The stone may harbour bacteria, making the infection difficult to clear completely with antibiotics. Requires investigation and stone treatment planning once the acute infection is controlled.
Emergency
Obstructive Pyelonephritis
Infection of the kidney behind an obstructing stone. The blocked, infected urine cannot drain, and antibiotics alone cannot penetrate effectively. This is a urological emergency requiring urgent decompression of the kidney.
Critical
Pyonephrosis
Pus accumulating within an obstructed kidney. Represents the most severe form of obstructive stone infection. The kidney is at risk of irreversible damage. Requires immediate drainage and IV antibiotics, often with ITU support.
Life-Threatening
Urosepsis
Sepsis originating from the urinary tract, most commonly triggered by an infected obstructed stone. Bacteria and toxins enter the bloodstream, causing a systemic inflammatory response. Requires immediate treatment.
Chronic
Struvite (Infection) Stones
Certain bacteria actively change components in the urine to cause kidney stones. These stones can grow rapidly and cause significant problems. Complete surgical clearance is essential because any residual fragments will harbour bacteria and regrow.
Warning Signs
Symptoms & Warning Signs
The combination of stone symptoms and infection signs should always raise alarm. The key principle is simple: fever plus stone pain equals emergency.
Stone Symptoms
● Severe back pain (renal colic)
● Pain radiating to the groin
● Nausea and vomiting
● Blood in the urine (haematuria)
Infection Signs
● Fever (temperature ≥ 38°C)
● Rigors (uncontrollable shaking/chills)
● Cloudy or foul-smelling urine
● Burning pain on urination (dysuria)
Sepsis Red Flags
● Rapid heart rate (tachycardia)
● Low blood pressure (hypotension)
● Confusion or altered consciousness
● Rapid or laboured breathing
Emergency Warning
If you have a known kidney stone and develop a fever, attend A&E immediately. An infected obstructed kidney will not resolve with oral antibiotics and requires emergency hospital treatment.
Diagnosis
How We Diagnose Stone-Related Infections
Rapid diagnosis is essential. The following investigations are performed urgently in any patient with suspected infected stone obstruction:
Blood Tests
Various blood tests are used to assess infection and how body systems are affected. Blood cultures identify the causative organism.
CT KUB
Non-contrast CT of the kidneys, ureters, and bladder is the gold standard for identifying stone location, size, and degree of obstruction. It can also reveal gas within the collecting system (emphysematous pyelonephritis) or perinephric abscess.
Ultrasound
Renal ultrasound can rapidly confirm hydronephrosis (swelling of the kidney due to obstruction) and may show echogenic debris within the collecting system suggestive of pyonephrosis. Often used as a bedside first-line test in the emergency setting.
Urine Culture
A midstream urine sample is sent for microscopy, culture, and sensitivity testing. Identifies the infecting organism and guides antibiotic selection.
Emergency Treatment
Emergency Management
The immediate priority is to treat the infection. Attempting stone removal during active infection may worsen the infection and is often delayed.
1
Resuscitation & IV Antibiotics
These are provided to support the body's ability to fight the infection.
2
Emergency Kidney Decompression
The infected, obstructed kidney must be drained urgently to allow the infection to drain. This is achieved by one of two methods:
Ureteric Stent (JJ Stent)
A thin tube inserted to bypass the stone and allow infected urine to drain. Performed under general or local anaesthetic.
Percutaneous Nephrostomy
A tube placed directly through the skin into the kidney under ultrasound or X-ray guidance by an interventional radiologist.
3
Definitive Stone Treatment — Later
Once the infection has fully cleared and the patient has recovered (typically 4–6 weeks later), the stone can be safely treated with definitive surgery. The stent or nephrostomy remains in place to keep the kidney drained during this interval.
Who should I see?
Meet your Specialist
At London Urology Specialists, the emergency assessment and definitive treatment of stone-related infections is led by Mr Alberto Coscione, a consultant urological surgeon with specialist expertise in endourology and the surgical management of obstructing and infected kidney stones.
Stone-Related Infections Are a Urological Emergency
An infected obstructed kidney can progress to life-threatening sepsis within hours. If you have a known kidney stone and develop a fever and feel unwell, present to A&E promptly. The kidney must be drained before the stone can be treated.
At London Urology Specialists, we provide rapid-access assessment and expert definitive stone surgery to ensure complete clearance and prevent recurrence. Our multidisciplinary approach combines surgical excellence with personalised metabolic prevention strategies.
Further Reading — UK Guidance & Patient Information
If you have a fever, severe pain and a known or suspected kidney stone, attend your nearest A&E immediately. Once the emergency has been treated, book a consultation with our specialist consultant for definitive stone management.
