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When Does Kidney Stone Need Surgery?

When Does Kidney Stone Need Surgery?

📖 9 min read Written/reviewed by Dr. Alhad Naragude, MBBS, MS, DrNB Urology Last updated: June 19, 2026

A kidney stone may need surgery if it is too large to pass, causes repeated severe pain, blocks urine flow, causes hydronephrosis, is linked with fever or urine infection, affects kidney function, or does not move despite observation. “Surgery” for kidney stones usually means minimally invasive treatment such as URSL, RIRS, shockwave lithotripsy or PCNL – not open surgery in most patients. Some small stones can pass with medicines and follow-up. But stones with infection, obstruction or kidney function risk need timely urologist evaluation.

When does kidney stone need surgery? The main situations

A kidney stone is more likely to need active treatment when:

Situation Why surgery or urgent treatment may be needed
Severe pain continues despite medicines The stone may be stuck and causing pressure in the kidney
Fever or chills are present A blocked infected kidney can become dangerous
Hydronephrosis is seen on USG/CT Urine flow from the kidney may be blocked
Creatinine is rising Kidney function may be under stress
Patient has a single kidney Even one blocked kidney can become serious
Stone is large Larger stones are less likely to pass naturally
Stone is growing Future pain, blockage or infection risk may increase
Blood in urine keeps recurring The stone may be irritating the urinary tract
Stone does not pass on follow-up Waiting may no longer be useful or safe
Work/travel makes sudden pain risky Planned treatment may be safer than emergency admission

The European Association of Urology lists stone growth, obstruction, infection, pain, blood in urine, patient health factors and social factors such as profession or travel among reasons to consider removal of kidney stones.

Does every kidney stone need surgery?

No. Many small kidney stones and ureter stones can pass without surgery.

Observation may be safe when the stone is small, pain is controlled, there is no fever, kidney function is normal, and the patient can come for follow-up. NICE also supports watchful waiting for selected asymptomatic renal stones after discussing risks and benefits with the patient.

But observation does not mean ignoring the stone. Follow-up imaging is important because a stone can move, grow, cause swelling or silently affect kidney function.

Emergency signs: when not to wait

Some kidney stone situations need urgent care.

Seek emergency care or urgent urology review if you have:

  • Fever with stone pain.
  • Chills or shivering.
  • Severe pain not controlled with medicines.
  • Repeated vomiting.
  • Reduced urine output.
  • Inability to pass urine.
  • Stone pain with a single kidney.
  • Stone pain with high creatinine.
  • Pregnancy with suspected stone pain.
  • Diabetes, kidney disease or low immunity with stone symptoms.

A stone with fever and blockage is especially dangerous. In this situation, the first step may be urgent drainage, not immediate stone removal. The urologist may place a DJ stent or nephrostomy tube to drain infected urine, start antibiotics, and plan final stone surgery after infection settles.

EAU guidance describes an obstructed infected kidney or anuria as a urological emergency needing urgent decompression with a stent or nephrostomy.

Stone size guide: when is surgery more likely?

Stone size helps, but it is not the only factor. Location, pain, infection, kidney swelling and kidney function matter equally.

Stone size/location Common treatment direction
Small ureter stone, no fever, pain controlled Observation, pain control, fluids, follow-up
Distal ureter stone under 10 mm May pass; medicines may help selected patients
Ureter stone 10-20 mm URSL/ureteroscopy is commonly advised
Kidney stone under 10 mm, no symptoms Observation may be possible
Kidney stone 10-20 mm SWL, RIRS or mini-PCNL depending on location and hardness
Lower pole kidney stone above 10 mm RIRS or PCNL may be better than SWL in many patients
Kidney stone above 20 mm or staghorn stone PCNL is usually preferred
Stone with fever, obstruction or kidney function risk Urgent urology care; drainage may be needed first

NICE recommends URS for many adult ureteric stones between 10 and 20 mm, and PCNL for renal stones larger than 20 mm, including staghorn stones. EAU also recommends PCNL as first-line treatment for larger renal stones above 2 cm.

Why pain alone is not enough to decide

Kidney stone pain can be severe even when the stone is small. On the other hand, a large stone inside the kidney may cause little pain until it blocks urine flow or causes infection.

A urologist usually decides based on the complete picture:

  • Stone size.
  • Stone location.
  • Degree of hydronephrosis.
  • Fever or urine infection.
  • Creatinine/kidney function.
  • Whether one or both kidneys are affected.
  • Previous stone history.
  • Stone hardness on CT.
  • Patient work, travel and ability to follow up.

A 5 mm lower ureter stone without fever may pass. A 5 mm stone with fever and kidney swelling may need urgent drainage.

Tests needed before deciding surgery

CT KUB

CT KUB is often the most useful test for stone planning. It shows the exact size, location, number of stones, density, obstruction and anatomy. NICE recommends urgent low-dose non-contrast CT within 24 hours for adults with suspected renal colic; ultrasound is preferred first in pregnancy and children.

USG KUB

Ultrasound can show hydronephrosis and some kidney stones. It is useful for follow-up and for patients where CT should be avoided, but it may miss small ureter stones.

Urine tests

Urine routine and urine culture help detect infection. If infection is present, it must be treated properly before planned stone surgery.

Blood tests

Serum creatinine shows kidney function. CBC may suggest infection. Serum calcium, uric acid and other metabolic tests may be advised in recurrent stone formers.

What are the surgery options for kidney stones?

1. Shockwave lithotripsy, or SWL/ESWL

SWL uses shockwaves from outside the body to break stones into smaller pieces that can pass in urine. It is usually suitable for selected smaller stones. It may not work well for very hard stones, large stones, lower pole stones, obese patients or stones that cannot be targeted clearly. NIDDK describes shockwave lithotripsy as a treatment that breaks stones into smaller fragments that pass through the urinary tract.

2. URSL or ureteroscopy

URSL is commonly used for stones stuck in the ureter. A thin telescope is passed through the urine passage into the bladder and ureter. The stone is removed or broken with laser. There is usually no external cut.

A DJ stent may be placed temporarily if there is swelling, infection risk, ureter narrowing, residual fragments or concern about urine drainage.

3. RIRS or flexible ureteroscopy

RIRS is used for stones inside the kidney. A flexible scope is passed through the natural urinary passage into the kidney, and the stone is dusted with laser. It is commonly used for selected kidney stones below 2 cm, depending on location, stone burden and anatomy.

4. PCNL

PCNL is a keyhole procedure through the back into the kidney. It is commonly used for large stones, hard stones, multiple stones and staghorn stones. EAU recommends PCNL as the first-line option for larger renal stones above 2 cm.

5. DJ stenting or nephrostomy

These are drainage procedures. They may be done urgently when the kidney is blocked, infected or under pressure. The stone may be removed later after the patient is stable.

Can kidney stone be treated without surgery?

Yes, if it is safe.

Non-surgical treatment may be possible when:

  • The stone is small.
  • Pain is controlled.
  • There is no fever.
  • Urine infection is absent or treated.
  • Kidney function is normal.
  • Hydronephrosis is mild or not worsening.
  • The patient can return for follow-up.

Alpha-blocker medicines may be considered for selected distal ureteric stones under 10 mm, but these medicines should be taken only after medical evaluation because they are not suitable for everyone. NICE recommends considering alpha blockers for distal ureteric stones under 10 mm.

What can happen if needed surgery is delayed?

Delay can lead to:

  • Repeated severe pain.
  • Emergency hospital visits.
  • Worsening hydronephrosis.
  • Urine infection.
  • Pus in the kidney.
  • Sepsis in infected obstruction.
  • Reduced kidney function.
  • More complex surgery later.

This does not mean every stone needs urgent surgery. It means stones with warning signs should not be ignored.

What to bring for consultation

Bring:

  • CT KUB film/report.
  • USG KUB report.
  • Urine routine/microscopy.
  • Urine culture, if fever or burning urination.
  • Serum creatinine.
  • CBC, if infection is suspected.
  • Previous stone surgery records.
  • Discharge summaries.
  • Current medicines, especially blood thinners.
  • Details of fever, vomiting, pain episodes and urine output.

Questions to ask your urologist

  • Is my stone likely to pass naturally?
  • Is my kidney swollen?
  • Is there infection?
  • Is my creatinine normal?
  • Do I need urgent drainage or planned surgery?
  • Which option is best for me: SWL, URSL, RIRS or PCNL?
  • Will I need a DJ stent?
  • How many days of rest will I need?
  • How can I prevent another stone?

FAQs

When does kidney stone need surgery?

A kidney stone may need surgery when it causes severe pain, blockage, fever, infection, hydronephrosis, kidney function risk, repeated symptoms, stone growth or is too large to pass naturally.

What size kidney stone needs surgery?

There is no fixed size for every patient. Many ureter stones above 10 mm and kidney stones above 20 mm need active treatment, but smaller stones may also need surgery if they cause infection, obstruction or kidney function problems.

Can a 5 mm kidney stone pass without surgery?

Yes, many 5 mm stones can pass, especially if they are lower in the ureter and there is no fever or kidney function problem. Follow-up is important.

Is fever with kidney stone dangerous?

Yes. Fever with a blocked stone can be dangerous and may need urgent drainage with a DJ stent or nephrostomy before final stone removal.

Does hydronephrosis always mean surgery?

Not always. Mild hydronephrosis may be observed in selected stable patients. Persistent, severe or infected hydronephrosis needs urgent urology evaluation.

Is kidney stone surgery painful?

Most stone procedures are done under anaesthesia. After surgery, patients may have burning urine, mild blood in urine, flank discomfort or DJ stent symptoms for a few days, depending on the procedure.

Is DJ stent placement the same as stone removal?

No. A DJ stent helps urine drain from the kidney to the bladder. It may be placed before, during or after stone treatment. The stone may still need URSL, RIRS, PCNL or SWL later.

Related reading

References

Note: This information is for educational purposes only and is not a substitute for medical advice. Please consult your doctor for any symptoms.