Blocked or Infected Kidney Stone
A kidney stone can sometimes block the flow of urine from the kidney. If infection develops behind that obstruction, urgent medical assessment and drainage of the kidney may be required before the stone itself is treated.
Fever or significant illness with a blocked kidney can be an emergency
Seek urgent medical assessment if suspected kidney stone obstruction is accompanied by fever, chills or rigors, significant illness, confusion or deterioration, difficulty passing urine, or severe symptoms that are not settling. Do not wait for a routine outpatient appointment if you are acutely unwell.
What does a “blocked kidney” mean?
Urine normally drains from the kidney through the ureter and into the bladder. A stone that becomes lodged within the ureter can partially or completely interfere with this drainage.
Pressure can then build within the urinary collecting system above the blockage. This dilation is often called hydronephrosis.
Obstruction can cause severe renal colic, but pain severity does not always tell us how much obstruction is present. Imaging is therefore important when obstruction is suspected.
Why is an infected obstructed kidney more serious?
Infection within a normally draining urinary system and infection behind an obstruction are not the same situation.
When a stone blocks drainage, infected urine may remain trapped above the obstruction. In a patient who is significantly unwell or septic, relieving that obstruction becomes an important part of treatment.
This is why the immediate priority may be to drain the kidney rather than remove the stone. Definitive stone surgery can then be considered once the acute infection has been appropriately treated.
What symptoms can occur?
Symptoms vary, and not every patient experiences every feature.
Severe Flank Pain
A stone blocking the ureter commonly causes significant pain in the side or back that can travel toward the abdomen or groin.
Fever
Fever in someone with suspected urinary obstruction raises concern for associated infection and requires medical assessment.
Chills or Rigors
Shaking chills or rigors can occur with significant infection and should not simply be attributed to kidney stone pain.
Nausea & Vomiting
Renal colic commonly causes nausea, while persistent vomiting can also make dehydration and recovery more difficult.
Feeling Very Unwell
Marked weakness, rapid deterioration, confusion or systemic illness requires urgent assessment.
Difficulty Passing Urine
Markedly reduced urine output or inability to pass urine requires urgent medical assessment.
How is a blocked or infected stone assessed?
Assessment usually combines the clinical picture with urine testing, blood tests and imaging.
Imaging helps establish where the stone is located and whether the kidney is obstructed. Blood and urine testing can provide information about infection and kidney function.
- Stone location and size
- Degree of urinary obstruction
- Temperature and clinical condition
- Urine testing or culture
- Kidney function
- Blood tests for infection where appropriate
- Whether one or both kidneys are affected
- Presence of a solitary functioning kidney
Why might the stone not be removed immediately?
When obstruction is associated with significant infection or sepsis, the immediate goal is often to restore urinary drainage and treat the infection.
Definitive ureteroscopy, laser treatment or another stone-removal procedure is generally delayed until the infection has settled. This separates the urgent problem — draining an infected obstructed kidney — from the later problem of removing the stone itself.
How can a blocked kidney be drained?
The two main approaches are an internal ureteric stent or a percutaneous nephrostomy tube. The choice depends on the clinical situation and local procedural considerations.
Ureteric Stent
A thin internal tube can be passed from the bladder through the ureter into the kidney. The stent creates a pathway for urine to drain past the obstruction.
The stone itself may remain in place until definitive treatment is performed later.
What to expect with a ureteric stent
Nephrostomy
A nephrostomy is a tube placed through the skin directly into the kidney collecting system. Urine drains externally into a collection bag.
It can provide rapid drainage when a kidney is obstructed and an internal ureteric stent is not the preferred drainage route.
Is a stent better than a nephrostomy?
Neither approach is universally better for every patient. Both can provide drainage from an obstructed kidney.
The choice can depend on the location and severity of the obstruction, anatomy, clinical condition, previous procedures and which approach can be performed appropriately and promptly.
In an acute infected obstruction, the important goal is effective decompression of the urinary system.
What happens after the kidney has been drained?
Emergency drainage treats the urgent obstruction. The stone itself may still need definitive treatment later.
Drain the Kidney
A ureteric stent or nephrostomy restores urine drainage from the obstructed kidney.
Treat the Infection
Infection is assessed and treated, with further microbiology testing used where appropriate.
Allow Recovery
Definitive stone treatment is generally deferred until the acute infection and systemic illness have resolved.
Treat the Stone
The remaining stone can then be treated according to its size, position and overall stone burden.
How is the stone treated afterwards?
Once the infection has settled and definitive treatment is appropriate, the stone can be reassessed according to its size and position.
Many obstructing ureteric stones are subsequently treated using ureteroscopy and laser surgery. Larger or more complex renal stone burdens may require another approach such as PCNL.
When significant infection occurs behind a urinary obstruction, restoring drainage can be an essential part of treatment. The presence of a mechanical blockage means that treatment may require both management of the infection and decompression of the urinary collecting system.
When does obstruction require particular attention?
Infection or Sepsis
Infection in an obstructed urinary system requires urgent assessment and may require prompt decompression.
Solitary Functioning Kidney
Obstruction of a patient's only functioning kidney can have particular implications for kidney function and requires prompt assessment.
Both Kidneys Obstructed
Bilateral urinary obstruction can compromise overall kidney function and requires urgent clinical evaluation.
Reduced Kidney Function
Kidney function helps determine the urgency and appropriate management of an obstructing stone.
Persistent Severe Pain
Pain that cannot be adequately controlled can itself be a reason to reconsider conservative management.
Ongoing Vomiting or Deterioration
Persistent vomiting, dehydration or clinical deterioration should prompt reassessment rather than prolonged observation at home.
Continue your kidney stone pathway
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Compare stone treatmentsBlocked & Infected Kidney Stone FAQs
What is an obstructed kidney stone?
An obstructing stone interferes with the normal flow of urine from the kidney, usually because it has become lodged within the ureter. This can cause dilation of the collecting system above the blockage.
How do I know if my kidney stone is infected?
Fever, chills or rigors and feeling significantly unwell can indicate infection. Urine and blood testing are often required to assess this properly. Infection with urinary obstruction requires urgent medical assessment.
Is an infected obstructed kidney an emergency?
Yes, it can be. An obstructed urinary system associated with sepsis or significant infection requires urgent assessment and may require prompt drainage with a ureteric stent or nephrostomy.
Why can't the stone just be lasered immediately?
When significant infection or sepsis is present behind an obstruction, the immediate priority is usually to drain the kidney and treat the infection. Definitive stone treatment is generally delayed until the acute infection has resolved.
What is a ureteric stent?
A ureteric stent is a thin internal tube that passes from the kidney to the bladder. It can maintain urine drainage past a stone or other ureteric obstruction.
What is a nephrostomy?
A nephrostomy is a drainage tube inserted through the skin directly into the kidney collecting system. Urine then drains externally into a bag.
Is a nephrostomy better than a ureteric stent?
Neither is universally better. Both can decompress an obstructed kidney. The most appropriate route depends on the clinical circumstances, anatomy and procedural considerations.
Does putting in a stent remove the kidney stone?
Usually not. A stent primarily restores or maintains urinary drainage. The stone may remain present and require definitive treatment later.
Will I still need kidney stone surgery after drainage?
Often the obstructing stone still requires treatment after the acute infection has settled. The later procedure depends on stone size, location and overall stone burden.
Can antibiotics alone treat an infected blocked kidney?
When significant infection occurs behind a urinary obstruction, antibiotic treatment may need to be combined with urgent drainage of the kidney. The appropriate treatment depends on the patient's clinical condition.
Can kidney obstruction damage kidney function?
Persistent or significant urinary obstruction can affect kidney function. The clinical importance depends on factors including the duration and severity of obstruction and whether one or both kidneys are involved.
What should I do if I have kidney stone pain and a fever?
Seek urgent medical assessment rather than waiting for a routine appointment. Fever or significant illness with a suspected obstructing stone can indicate infection behind the obstruction.
Have you recently been treated for a blocked or infected kidney stone?
Once the acute infection or obstruction has been managed, imaging and treatment history can be reviewed to plan definitive treatment of the remaining stone and consider strategies to reduce future stone risk.
This page provides general educational information and is not intended for the assessment of an acute medical emergency. If you have fever, chills, significant illness or clinical deterioration with a suspected obstructing kidney stone, seek urgent medical assessment. Individual treatment depends on the degree of obstruction, infection, kidney function, stone location, anatomy and other clinical circumstances.