A 20 mm kidney stone measures approximately 2 centimetres. At this size, spontaneous passage is generally unlikely, and active treatment is often considered rather than waiting for the stone to pass on its own.

Kidney stone treatment is not selected by size alone. The doctor also considers:

• Where the stone is located

• Whether it is inside the kidney or ureter

• Stone density and composition

• Whether urine flow is obstructed

• Presence of infection

• Kidney function

• Symptoms

• Kidney anatomy

• Previous stone treatments

• Overall health and anesthesia-related considerations

Larger stones are more likely to become stuck or cause obstruction, and treatment may involve shock-wave lithotripsy, ureteroscopy or percutaneous nephrolithotomy depending on the circumstances.

At Prabhakar Bhurke Clinic, Dr. Sandip Prabhakar Bhurke, super specialist nephrologist and transplant physician, provides kidney-function evaluation and specialist management for patients with kidney stones and related kidney problems.

Can a 20 mm Kidney Stone Pass Naturally?

A stone measuring 20 mm is considerably larger than stones that commonly pass spontaneously.

The chance of natural passage decreases as stone size increases. A large stone can remain within the kidney or become lodged in the ureter, potentially interfering with urine drainage.

Therefore, attempting to pass a 20 mm stone at home by simply drinking large quantities of water is generally not an appropriate treatment strategy.

A specialist should assess the stone and determine whether observation is reasonable or whether active removal is advisable.

Does Every 20 mm Stone Need the Same Procedure?

No.

Two people can both have a 20 mm stone but require different treatments.

For example, treatment planning may differ if:

• One stone is in the renal pelvis and another is in the lower kidney.

• One stone is relatively soft and another is very dense.

• One patient has normal kidney function while another has reduced kidney function.

• One stone causes obstruction or infection.

• One patient has already undergone unsuccessful stone treatment.

Imaging, particularly appropriate CT imaging when indicated, can provide information needed to plan treatment.

Where Is the 20 mm Stone Located?

The stone's location is one of the most important factors in treatment selection.

Renal Pelvis

A stone in the renal pelvis may interfere with urine drainage and can often be approached using endoscopic or percutaneous techniques depending on its characteristics.

Kidney Calyx

A calyceal stone may be managed differently depending on its location.

Lower-pole stones can sometimes be more difficult to clear completely because fragments may remain within the lower calyx.

Ureter

A 20 mm stone located in the ureter is very unlikely to pass naturally and may require active removal.

Ureteroscopy with stone fragmentation and extraction is one of the established treatment approaches.

How Is a 20 mm Kidney Stone Evaluated?

Before deciding on treatment, the doctor may review several investigations.

CT Scan

A non-contrast CT scan can provide detailed information about:

• Exact stone location

• Stone size

• Number of stones

• Stone density

• Urinary obstruction

• Kidney anatomy

These details can help the treating team select an appropriate procedure.

Ultrasound

Ultrasound may help identify stones, hydronephrosis and other abnormalities.

It can also be useful during follow-up.

Urine Testing

Testing may look for:

• Blood

• Infection

• Protein

• Other urinary abnormalities

If infection is suspected, a urine culture may be required.

Blood Tests

Depending on the situation, testing may include:

• Serum creatinine

• eGFR

• Urea

• Electrolytes

• Blood count

• Other relevant tests

These investigations help determine whether the stone is affecting kidney function and whether the patient is medically ready for a procedure.

What Is the Best Treatment for a 20 mm Kidney Stone?

There is no single procedure that is automatically best for every 20 mm stone.

The main active treatment options include:

1. Percutaneous nephrolithotomy (PCNL)

2. Flexible ureteroscopy or RIRS with laser lithotripsy

3. Shock-wave lithotripsy (SWL or ESWL) in selected situations

4. Staged or combined procedures when necessary

NIDDK identifies SWL, ureteroscopy and PCNL among the established methods used to break or remove kidney stones, with treatment selection influenced by stone size and other characteristics.

PCNL for a 20 mm Kidney Stone

Percutaneous nephrolithotomy (PCNL) involves creating a small access tract through the skin into the kidney.

A nephroscope is passed through this tract, allowing the surgeon to fragment and remove the stone.

PCNL is an important treatment option for larger renal stones and may be particularly useful when a substantial stone burden needs to be cleared efficiently.

Potential advantages include:

• Direct access to the kidney

• Ability to remove larger stone fragments

• Useful for substantial stone burden

• Often effective when a single large stone needs significant clearance

However, PCNL is still an invasive procedure and has potential risks such as bleeding, infection and injury to surrounding structures. The suitability of the procedure depends on individual anatomy and health.

Laser Treatment for a 20 mm Stone

Another approach is flexible ureteroscopy or RIRS with laser lithotripsy.

A small flexible scope is introduced through the urinary tract and guided toward the kidney. Laser energy can fragment the stone into smaller pieces.

Depending on the stone burden, the fragments may be extracted using a basket or reduced to small particles that can pass through the urinary tract.

For a 20 mm stone, the treating specialist may recommend one session or a staged approach depending on stone characteristics and the expected clearance rate.

Ureteroscopy allows the doctor to directly visualize the urinary tract and treat the stone from within the natural urinary passage.

Can RIRS Be Used for a 20 mm Kidney Stone?

Yes, in selected patients.

RIRS is a form of flexible ureteroscopy used to reach stones inside the kidney.

It may be considered when:

• The stone's location is suitable

• The anatomy allows access

• The stone burden can reasonably be treated endoscopically

• The patient's medical condition favors this approach

For some large stones, more than one procedure may be needed.

The decision between RIRS and PCNL should be made after reviewing imaging, stone characteristics and patient-specific factors.

Is ESWL Suitable for a 20 mm Kidney Stone?

ESWL or SWL may be considered in selected cases, but a 20 mm stone presents challenges for shock-wave treatment.

SWL uses focused shock waves generated outside the body to break the stone into smaller pieces, which can then pass through the urinary tract.

Its effectiveness can be influenced by:

• Stone size

• Stone density

• Stone composition

• Stone location

• Skin-to-stone distance

• Kidney anatomy

• Obstruction

• Body habitus

A large stone may require multiple treatment sessions, and residual fragments can remain after fragmentation.

For this reason, SWL is not automatically the preferred option for every 20 mm stone.

20 mm Kidney Stone Treatment Without Surgery

Many people search for 20 mm kidney stone treatment without surgery.

For a stone of this size, however, medicines and home remedies generally cannot be expected to physically remove most stones.

There are limited exceptions. Certain uric acid stones may be medically dissolved through carefully supervised urine alkalinization.

Most calcium-based stones, which are common, cannot simply be dissolved with ordinary tablets or home remedies.

Therefore, the stone's composition and clinical situation need to be considered before deciding that non-surgical management is appropriate.

Can Drinking More Water Remove a 20 mm Stone?

Drinking an appropriate amount of fluid is important for preventing future stones and maintaining hydration.

However, excessive water intake does not reliably push a 20 mm stone out of the urinary tract.

If a stone is obstructing urine flow, forcing large volumes of water may increase discomfort without removing the blockage.

Patients with kidney failure, heart disease or prescribed fluid restrictions should be particularly careful about increasing fluid intake without medical advice.

What If a 20 mm Stone Is Blocking Urine?

A large stone can obstruct the urinary tract.

Possible consequences include:

• Hydronephrosis

• Reduced kidney function

• Severe pain

• Recurrent urinary infection

• Infection behind an obstruction

A blocked urinary system accompanied by infection requires urgent medical attention.

In such circumstances, the priority may be to establish urine drainage with a ureteral stent or nephrostomy before definitive stone removal, depending on the patient's condition.

Can a 20 mm Kidney Stone Cause Kidney Damage?

It can, particularly if it produces persistent obstruction, recurrent infection or significant pressure-related changes in the urinary system.

The risk depends on:

• Duration of obstruction

• Whether one or both kidneys are affected

• Presence of infection

• Baseline kidney function

• Degree of obstruction

A person with a large stone and abnormal creatinine should therefore receive appropriate kidney-function assessment.

What Happens If Both Kidneys Have Large Stones?

If stones are present in both kidneys, treatment planning becomes more complex.

The doctor may consider:

• Size of each stone

• Location of each stone

• Kidney function

• Degree of obstruction

• Infection status

• Symptoms

• Whether one kidney is functioning better than the other

In selected patients, treatment may be staged rather than treating both sides simultaneously.

The safest approach depends on the individual's anatomy and clinical condition.

What Happens Before 20 mm Kidney Stone Surgery?

Before treatment, the medical team may review:

• CT or ultrasound findings

• Stone location and density

• Kidney function

• Urine culture

• Blood tests

• Current medications

• Blood-thinning medicines

• Diabetes and blood pressure

• Previous stone procedures

• Anesthesia-related risks

If a urinary infection is present, it generally needs appropriate treatment before definitive stone removal unless urgent drainage is required.

The treating team will also discuss the expected stone-clearance rate, possibility of a stent and the possibility of requiring additional procedures.

Can a 20 mm Stone Be Removed in One Procedure?

Sometimes, but not always.

The likelihood of complete clearance depends on:

• Stone size

• Number of stones

• Stone density

• Location

• Kidney anatomy

• Chosen treatment

• Previous procedures

PCNL may allow substantial stone clearance in an appropriate patient, while RIRS or SWL may sometimes require additional sessions.

The goal is safe and effective stone clearance rather than choosing a procedure solely because it promises a single session.

Is a Stent Required After Stone Treatment?

A ureteral stent may be placed after some stone procedures.

A stent can help maintain urine drainage while the ureter recovers or while stone fragments pass.

Patients with a stent may experience:

• Urinary urgency

• Frequent urination

• Burning

• Flank discomfort

• Blood in urine

A stent is usually temporary and should be removed or exchanged according to the treating specialist's instructions.

Recovery After 20 mm Kidney Stone Treatment

Recovery depends on the procedure used.

After treatment, temporary symptoms may include:

• Mild blood in urine

• Burning during urination

• Urinary frequency

• Flank discomfort

• Passage of small fragments

• Stent-related discomfort

PCNL may require a longer recovery period than some ureteroscopic procedures.

Your treating specialist will provide individualized instructions regarding medicines, activity, hydration, diet and follow-up imaging.

When Should a 20 mm Kidney Stone Be Treated Urgently?

Urgent medical assessment is particularly important when a large stone is accompanied by:

• Fever

• Chills

• Severe or worsening pain

• Persistent vomiting

• Very little urine

• No urine

• Confusion

• Severe weakness

• Rapid deterioration

A stone that blocks urine flow and is associated with infection can become a serious medical emergency.

Larger or obstructing stones may require prompt intervention rather than prolonged observation.

How Can Another Kidney Stone Be Prevented?

Removing the current stone is only one part of long-term stone care.

After treatment, the doctor may recommend stone analysis and, particularly for recurrent stone formers, metabolic evaluation.

Preventive measures can include:

• Maintaining appropriate fluid intake

• Reducing excessive dietary sodium

• Following an individualized diet

• Maintaining appropriate dietary calcium rather than unnecessarily eliminating calcium

• Taking prescribed preventive medicines

• Treating recurrent urinary infections

• Completing recommended follow-up testing

NIDDK notes that stone analysis and urine evaluation can help identify factors contributing to recurrent stone formation.

Why Specialist Assessment Matters for a 20 mm Kidney Stone

A 20 mm stone is large enough that simply focusing on pain relief may not address the underlying problem.

A specialist assessment helps determine:

• Whether the stone needs active removal

• Whether the kidney is obstructed

• Whether infection is present

• Which procedure is technically appropriate

• Whether one or more procedures may be required

• How to protect kidney function

• How to reduce future stone recurrence

The decision should be based on imaging, laboratory findings and the patient's overall health.

Kidney Stone Evaluation at Prabhakar Bhurke Clinic

At Prabhakar Bhurke Clinic, Dr. Sandip Prabhakar Bhurke, super specialist nephrologist and transplant physician, provides specialist evaluation for patients with kidney stones and associated kidney-function concerns.

Depending on the clinical situation, care may include:

• Review of CT and ultrasound reports

• Creatinine and eGFR assessment

• Evaluation of urinary obstruction

• Assessment of infection

• Kidney-function monitoring

• Medical management of associated kidney conditions

• Stone-prevention guidance

• Assessment of dialysis-related kidney complications when relevant

• Coordination with an appropriate urological stone-removal specialist when a procedure is required

Treatment is individualized according to stone characteristics, kidney function, symptoms and overall medical condition.

Frequently Asked Questions

Can a 20 mm kidney stone pass naturally?

A 20 mm stone is unlikely to pass naturally. Because larger stones have a lower likelihood of spontaneous passage, active treatment is commonly considered depending on location, symptoms and obstruction.

What is the best treatment for a 20 mm kidney stone?

There is no single best procedure for every patient. PCNL, flexible ureteroscopy or RIRS with laser treatment, and selected cases of SWL may be considered depending on stone size, location, density, anatomy and patient factors.

Is PCNL suitable for a 20 mm kidney stone?

PCNL can be an important option for larger renal stones, particularly when substantial stone clearance is required. The final decision depends on imaging, anatomy, medical history and the treating specialist's assessment.

Can laser treatment remove a 20 mm kidney stone?

Yes. Flexible ureteroscopy or RIRS can use laser energy to fragment a 20 mm stone in selected patients. A staged procedure may sometimes be necessary.

Can ESWL remove a 20 mm stone?

ESWL can fragment kidney stones, but its effectiveness depends on stone size, location, density and other factors. Larger stones may require multiple sessions or another treatment approach.

Can medicine dissolve a 20 mm kidney stone?

Most common kidney stones cannot be dissolved with medication. Selected uric acid stones may respond to medically supervised urine alkalinization.

Can drinking more water remove a 20 mm stone?

No. Appropriate hydration is important, but excessive water intake does not reliably remove a stone of this size and can be harmful in some patients.

How long can a 20 mm kidney stone stay untreated?

There is no universal safe duration. A stone may remain stable for some time, but persistent obstruction, infection, pain or kidney-function impairment can make delayed treatment unsafe. Specialist assessment is important.

Conclusion

A 20 mm kidney stone is a large stone that is unlikely to pass naturally and often requires an active treatment plan.

The most appropriate procedure depends on much more than the measurement alone. Stone location, density, kidney anatomy, obstruction, infection, kidney function and the patient's overall health all influence treatment selection.

Depending on these factors, treatment may involve PCNL, flexible ureteroscopy or RIRS with laser lithotripsy, SWL, or a staged approach. Large or obstructing stones should not be managed by relying solely on excessive water intake or unproven stone-breaking medicines.

Prompt assessment is especially important when a 20 mm stone causes severe pain, reduced urine output, urinary obstruction, fever or infection.

For specialist kidney evaluation and individualized management, consult Dr. Sandip Prabhakar Bhurke at Prabhakar Bhurke Clinic.

Medical Disclaimer

This article is intended for general educational and informational purposes only and should not be considered a substitute for medical diagnosis, treatment or individualized medical advice. A 20 mm kidney stone may require active removal, but the appropriate procedure depends on its location, composition or density, anatomy, obstruction, infection status, kidney function and the patient's overall health. PCNL, ureteroscopy with laser treatment and SWL are not equally suitable for every patient, and some patients may require staged or combined treatment. Do not attempt to force a large stone to pass by drinking excessive amounts of water or by taking unprescribed medicines or herbal remedies. Fever, chills, severe pain, persistent vomiting, very little or no urine, confusion or sudden worsening may indicate a serious complication requiring urgent medical attention. Consult Dr. Sandip Prabhakar Bhurke or an appropriately qualified kidney and urinary stone specialist for an individualized treatment plan.