When Does a Kidney Stone Need Surgery?
Not every kidney stone needs an operation. Some can be safely monitored or allowed time to pass, while others are more likely to require treatment because of pain, obstruction, infection, stone growth or a low chance of passing naturally.
Some kidney stones need urgent rather than elective treatment
Seek urgent medical assessment if suspected stone obstruction is accompanied by fever, chills or significant illness, or if you are unable to pass urine. An infected obstructed urinary system can require urgent drainage rather than waiting for routine stone surgery.
Does every kidney stone need surgery?
No. Kidney stones behave very differently depending on their size, location and the effect they are having on the urinary system.
A small stone sitting quietly within the kidney may sometimes be monitored. A small ureteric stone may have a reasonable chance of passing naturally.
In contrast, a stone causing persistent obstruction, significant symptoms, infection or progressive growth may be more likely to benefit from active treatment.
The decision is therefore based on the whole clinical picture rather than one stone measurement alone.
What makes kidney stone surgery more likely?
Several factors can shift the balance from observation toward active stone treatment.
Persistent or Severe Pain
Recurrent renal colic or pain that remains difficult to control may favour active treatment rather than continued observation.
Urinary Obstruction
A stone that continues to block urine drainage from the kidney may need treatment, particularly if the obstruction is persistent or affecting kidney function.
Infection
Stones associated with urinary infection require careful assessment. Infection together with obstruction can require urgent drainage.
Stone Growth
A kidney stone that is increasing in size on follow-up imaging may be more likely to warrant active treatment.
Low Chance of Passing
Larger ureteric stones and stones in some locations have a lower likelihood of passing without intervention.
Kidney Function at Risk
Reduced kidney function, obstruction affecting both kidneys or obstruction of a solitary functioning kidney requires particular consideration.
When might a kidney stone be monitored instead?
Observation may be reasonable
Selected kidney stones that are not causing symptoms, infection or obstruction and remain stable on imaging may sometimes be monitored rather than treated immediately.
- No significant symptoms
- No associated infection
- No concerning urinary obstruction
- Kidney function is not threatened
- Stone remains stable on surveillance
A trial of spontaneous passage may be reasonable
Selected smaller ureteric stones may be given time to pass naturally when symptoms can be controlled and complications are not developing.
- Reasonable likelihood of spontaneous passage
- Pain can be adequately controlled
- No significant infection
- No concerning deterioration in kidney function
- Follow-up is arranged where appropriate
Is there a kidney stone size that automatically means surgery?
No single measurement determines treatment in every patient. Stone size is important, but location, symptoms, obstruction, infection, kidney anatomy, stone density and individual circumstances also matter.
For kidney stones greater than about 2 cm, active treatment is usually more likely to involve PCNL because larger stone burdens become less suitable for some other approaches. Smaller stones can still require surgery if they are causing problems.
Likewise, a relatively small stone stuck within the ureter may need treatment if it causes persistent obstruction or uncontrolled symptoms.
When does a ureteric stone need surgery?
Many small ureteric stones pass naturally, but spontaneous passage becomes less likely as stone size increases.
Active removal becomes more relevant when the stone has a low chance of passing, pain remains difficult to control, obstruction persists or kidney function is threatened.
When treatment is required, ureteroscopy and laser surgery is a common approach for ureteric stones.
An infected obstructed kidney is different from routine stone surgery
When infection is present behind an obstruction, the immediate priority may be drainage of the kidney with a ureteric stent or nephrostomy rather than removal of the stone. Definitive stone treatment is generally planned after the infection has been appropriately treated.
What determines whether I actually need treatment?
Imaging is considered together with your symptoms, kidney function, infection risk and medical history.
A CT scan can provide detailed information about the size, location and density of the stone, whether the kidney is obstructed and the anatomy relevant to treatment.
Which kidney stone procedure might be used?
Needing treatment does not automatically mean needing one particular operation. The procedure is selected according to the stone.
Ureteroscopy & Laser
Fine telescopes are passed through the urinary tract to reach selected ureteric and kidney stones. Laser energy can then be used to fragment the stone where appropriate.
Learn about ureteroscopyShock Wave Lithotripsy
Shock waves generated outside the body can fragment selected stones. Suitability depends on factors including stone location, size, density and anatomy.
PCNL
Percutaneous nephrolithotomy provides direct keyhole access into the kidney and is an important first-line pathway for larger renal stone burdens.
Learn about PCNL
What if my kidney stone is larger than 2 cm?
Larger kidney stone burdens are less likely to be suited to observation when active treatment is otherwise indicated.
For renal stones greater than 2 cm, PCNL is generally the principal first-line surgical approach. Flexible ureteroscopy can still have a role in selected situations, although more than one procedure may be required.
Your circumstances can also influence the decision
Stone treatment is not decided from the CT scan alone. The impact of repeated attacks, work requirements, travel, access to emergency medical care, previous stone events, other medical conditions and personal preference can all be relevant.
This is particularly important when both observation and active treatment are reasonable options. The role of the consultation is to understand the likely natural history of the stone and the advantages and limitations of each available pathway.
How is the decision made?
Review the Scan
Establish stone size, location, burden and whether urinary obstruction is present.
Assess the Clinical Risk
Consider symptoms, infection, kidney function and the likelihood of spontaneous stone passage.
Observe or Treat
Decide whether surveillance or spontaneous passage is reasonable or whether active stone removal is more appropriate.
Choose the Procedure
Where treatment is needed, select the approach according to the stone, anatomy and individual circumstances.
Explore the treatment pathways
Kidney Stones
Understand kidney stone symptoms, diagnosis, surveillance and the main treatment options.
Explore kidney stones ProcedureUreteroscopy & Laser Surgery
Learn about endoscopic treatment of selected ureteric and kidney stones.
Explore ureteroscopy Larger StonesPCNL
Learn about direct keyhole treatment for selected larger and complex kidney stones.
Explore PCNLKidney Stone Surgery FAQs
Does every kidney stone need surgery?
No. Selected stones can be monitored or allowed time to pass naturally. Surgery becomes more relevant when there is significant pain, persistent obstruction, infection, stone growth, reduced kidney function or a low likelihood of spontaneous passage.
What size kidney stone needs surgery?
There is no single size that automatically means every patient needs surgery. Larger stones are generally less likely to pass and may require different treatment, but location, symptoms, obstruction, infection and kidney function also influence the decision.
Does a 5 mm kidney stone need surgery?
Not necessarily. A 5 mm stone may sometimes be observed or pass naturally, particularly if it is within the ureter and there are no complications. Its location and the individual clinical situation are important.
Does a 10 mm kidney stone need surgery?
A 10 mm stone is less likely to pass naturally than a smaller stone, particularly if it is in the ureter, but treatment should not be based on diameter alone. Location, symptoms, obstruction and other clinical factors need to be considered.
Does a 2 cm kidney stone need surgery?
A renal stone around or above 2 cm represents a larger stone burden. When active removal is indicated, PCNL is generally the principal first-line treatment for renal stones above 2 cm. Individual health, anatomy and other clinical factors still need to be considered.
Can I wait for a kidney stone to pass?
Selected ureteric stones can be given time to pass when the likelihood of spontaneous passage is reasonable, pain is controlled and complications such as infection or deterioration in kidney function are not developing.
How long can I wait for a ureteric stone to pass?
There is no single safe waiting period for every stone. Stone size and location, symptoms, obstruction, infection and kidney function determine whether continued observation remains appropriate. Follow-up may be needed to confirm passage.
If the pain stops, does that mean the stone has passed?
Not always. Symptoms can settle even when a stone remains within the urinary tract. Depending on the situation, follow-up imaging may be appropriate to confirm passage and resolution of obstruction.
When is a kidney stone an emergency?
An obstructed urinary system associated with infection can be a urological emergency. Fever, chills or significant illness with suspected obstruction should prompt urgent medical assessment. Inability to pass urine also requires urgent assessment.
If I need surgery, will I have ureteroscopy or PCNL?
The procedure depends on the size, position and burden of the stone and on kidney anatomy and other individual factors. Ureteroscopy is commonly used for selected ureteric and kidney stones, while PCNL is particularly important for larger and complex renal stone burdens.
Can I choose to have a stone removed even if it is not causing pain?
Patient preference can form part of treatment planning. The likely natural history of the stone, risks of intervention, occupation, travel and access to future medical care can all be considered when deciding between surveillance and treatment.
Not sure whether your kidney stone needs surgery?
Your CT or other imaging can be reviewed together with your symptoms, kidney function and stone history to determine whether observation or active treatment may be more appropriate and, if treatment is needed, which approach best fits the stone.
This information is general educational information and does not replace individual medical advice. The decision to monitor or treat a kidney stone depends on factors including stone size and location, symptoms, urinary obstruction, infection, kidney function, stone growth, anatomy and individual clinical circumstances.