How Long Do You Stay in the Hospital for Kidney Stones?

Most people who show up at the emergency room with a kidney stone go home the same day. A large U.S. study found that only about 8% of ER visits for uncomplicated kidney stones led to a hospital admission, and just 6% involved an inpatient procedure. For the majority, the visit means pain control, imaging, and discharge with instructions to pass the stone at home. When surgery is needed, the type of procedure is what shapes your stay, ranging from a few hours for scope-based treatments to a couple of nights for more invasive approaches.

Most ER Visits End With Discharge

Kidney stone pain can feel catastrophic, and the emergency department is where many people first get diagnosed. But the ER’s main job in an uncomplicated stone episode is to confirm what’s going on, rule out dangerous complications, and get the pain under control. In 2011, more than a million ER visits in the United States were attributed to uncomplicated kidney stones, and roughly 92% of those patients went home afterward.¹ “Uncomplicated” is doing real work in that sentence: it means no signs of infection, no acute kidney injury, and a stone small enough that it has a reasonable chance of passing on its own.

One uncomfortable wrinkle in the data is that insurance status affected outcomes. Uninsured patients were less likely to be admitted or to receive an inpatient procedure compared to those on Medicaid, even after accounting for other factors.¹ That gap suggests the decision to admit is not purely medical.

What Triggers an Admission

When doctors do keep you overnight, specific red flags are usually driving the decision. Research looking at emergency department patients with CT-confirmed ureteral stones found that admitted patients were more likely to show evidence of kidney injury or infection, need opiate-level pain relief, have larger stones, or have visible swelling of the kidney on ultrasound.² A history of prior stone procedures also raised the odds of being admitted.

In practical terms, the factors that most reliably send you from the ER to a hospital bed are:

Infection: A stone blocking urine flow with bacteria behind it can become life-threatening fast, so this almost always means admission and usually urgent drainage.
Uncontrollable pain: If ER medications cannot bring the pain down to a manageable level, you stay.
Kidney function decline: Rising creatinine or other signs that the blocked kidney is struggling.
Stone size: Larger stones are less likely to pass and more likely to need a procedure, which means admission for surgical planning.

How Stone Size Shapes Whether You Need Surgery at All

The question of how long you stay in the hospital is often really a question of whether you need surgery, and that comes down to the stone’s size and location. Smaller stones overwhelmingly pass on their own. A study tracking nearly 400 ureteral stones found spontaneous passage rates of 98% for stones up to 3 mm wide, 81% for 4 mm stones, 65% for 5 mm stones, and only 9% for stones 6.5 mm or larger.³ Location matters too: stones closer to the bladder pass more readily than those stuck higher in the ureter.⁴

Even when stones do pass naturally, the timeline can be surprisingly long. For stones 2 mm or smaller, the average passage time was about 8 days. For stones between 2 and 4 mm, about 12 days. For stones 4 mm and up, the average stretched to 22 days, and for 95% of those stones to clear, patients waited roughly 5 to 6 weeks.⁵ None of that time is spent in the hospital, but it is spent in varying degrees of discomfort at home.

You may have heard that a medication called tamsulosin can speed things along. The evidence here is genuinely mixed. One older study found tamsulosin boosted passage rates and cut the average time from about 7.5 days to 4.4 days.⁶ But a larger randomized trial found no meaningful difference in passage time, surgery rates, or hospitalization between tamsulosin and placebo.⁷ A more recent comparative study similarly found no significant improvement in passage rates or time, though patients taking the medication did have fewer ER visits for recurrent pain episodes.⁸ The bottom line: tamsulosin probably helps with comfort more than it helps stones pass faster, and it is unlikely to be the difference between needing surgery and not.

Ureteroscopy Is Usually a Same-Day Procedure

When a stone will not pass on its own and needs to be removed, the most common approach for stones in the ureter or lower kidney is ureteroscopy. A thin scope is passed through the bladder and up the ureter, and the stone is either grabbed whole or broken apart with a laser. The hospital stay for this procedure is often measured in hours, not days. A study at one university hospital reported a mean hospital stay of half a day for flexible ureteroscopy with laser treatment, with many patients going home the same day.⁹

Research specifically evaluating ureteroscopy as a day-case procedure found it was safe for both rigid and flexible approaches, with only a small fraction of patients needing unplanned overnight admission, usually because of post-procedure pain or logistical reasons.¹⁰ If you’re having ureteroscopy for a kidney stone, the most realistic expectation in 2025 is that you arrive in the morning and leave in the afternoon or evening.

PCNL Means a Longer Stay, but the Trend Is Shorter

Percutaneous nephrolithotomy, or PCNL, is reserved for larger or more complex stones, typically those bigger than 2 cm or in locations that a scope cannot easily reach. The surgeon makes a small incision in the back and passes instruments directly into the kidney. This is a bigger procedure, and historically it has meant at least one or two nights in the hospital. One study reported a mean stay of about 1.7 days, with roughly 20% of patients staying longer than one night because of surgical factors like bleeding or residual fragments.¹¹

A growing body of work, though, is pushing toward same-day discharge even after PCNL. A review of studies comparing outpatient PCNL to traditional inpatient stays found no difference in complication rates, ER visits, or readmissions, and the outpatient approach saved substantially on costs.¹² Another study comparing same-day discharge PCNL patients to overnight controls found that complication rates were actually lower in the same-day group, readmission rates were similar, and the total cost dropped by about $2,800 per case.¹³ This does not mean every PCNL patient can go home the same day, but increasingly, carefully selected patients are doing so without worse outcomes. The “mini-PCNL” technique, which uses smaller instruments, is particularly suited to same-day discharge.

The Stent Question and What It Means for Your Recovery

After ureteroscopy, many surgeons place a ureteral stent, a thin tube running from the kidney to the bladder, to keep things draining while swelling goes down. Stents are infamous for causing discomfort, urgency, and blood in the urine for the days to weeks they remain in place. A reasonable question is whether stents actually help or whether they add to your post-procedure burden.

The data on this point are not as tidy as you might hope. One study found that patients who had a stent already in place before ureteroscopy were actually less likely to end up back in the ER afterward.¹⁴ A separate large analysis found no association between stent placement and ER visits or hospital readmissions in the week after surgery.¹⁵ But a statewide collaborative study found the opposite: stent placement was linked to 25% higher odds of an ER visit after ureteroscopy, though it did not significantly increase actual hospital readmission.¹⁶ The picture that emerges is that stents probably do not change whether you get readmitted, but the discomfort they cause may drive some people back to the ER for pain management. The stent itself does not extend your initial hospital stay.

Readmission Rates After Stone Surgery

Coming back to the hospital after stone surgery is relatively uncommon but not rare. After ureteroscopy, about 7% of patients visited the ER within 30 days in one study, and about 3% were actually readmitted.¹⁷ Older age and a history of recurrent urinary tract infections raised the odds of readmission.¹⁷

PCNL carries a higher readmission risk. One comparative study found readmission rates of about 27% after PCNL versus 20% after retrograde intrarenal surgery (the scope-based approach), a significant difference. Perioperative complications and residual stone fragments were strong predictors of readmission for both procedure types.¹⁸ Among all patients undergoing endo-urological stone procedures at another center, the overall 30-day readmission rate was under 2%, with sepsis and bleeding as the most common reasons for return.¹⁹ The wide spread across studies probably reflects differences in how complex the stones were and how “readmission” was defined.

Older Adults Stay Longer

Age is one of the strongest predictors of a longer hospital stay for kidney stones. Adults 65 and older use inpatient care at disproportionately high rates for stone disease. Their median stay was about 3 days, with a full quarter staying nearly 6 days or more.²⁰ Some of this reflects the higher likelihood of complicated presentations in older patients, such as infections, impaired kidney function, and coexisting medical conditions that need managing alongside the stone.

Frailty adds another layer. Research on frail patients hospitalized for stone surgery found they faced higher costs, were more likely to be discharged somewhere other than home, and had nearly twice the odds of perioperative complications.²¹ Frail patients were also less likely to get surgery within 24 hours of admission, which itself may lengthen the total stay.²¹

Pregnancy Changes Everything

Kidney stones during pregnancy present a distinct challenge because imaging options are limited (CT scans are generally avoided) and many standard treatments cannot be used. Pregnant women with kidney stones had a mean hospital stay of about 5 days, roughly double that of pregnant women without stones.²² They were also less likely to present with the classic flank pain that makes diagnosis straightforward and less likely to undergo invasive or surgical procedures.²³ The longer stay reflects a more conservative management approach: doctors tend to favor watchful waiting, hydration, and pain control while monitoring both the mother and fetus, which takes more time than the straightforward “treat it and discharge” approach used in non-pregnant adults.

Children and Kidney Stones

Pediatric kidney stones are uncommon but increasing. By the late 2000s, stone disease accounted for roughly 1 in 685 pediatric hospitalizations in the United States.²⁴ When children undergo PCNL, the national median stay has been around 3 to 4 days, though regional variation is real, with stays in the western United States averaging a day longer than in other parts of the country.²⁵

There is evidence, however, that most children can be discharged after just one day if there are no surgical complications. In one series, about 84% of pediatric PCNL patients went home after a single overnight stay, while the remaining 16% stayed longer, almost always because of a complication that arose during or after surgery.²⁶ In that study, the presence of a surgical complication was the only significant predictor of a longer stay, not stone size, patient age, or other characteristics.²⁶

Pain Control and Its Role in Getting Home Sooner

One underappreciated factor in how long you stay is how well the pain is managed. Kidney stone pain, renal colic, can be severe enough that patients who would otherwise be discharged need to stay simply because they cannot stop vomiting or cannot tolerate oral medications. Patients who require opiate-level pain relief in the ER are more likely to be admitted.²

The shift toward opioid-sparing approaches, using NSAIDs, acetaminophen, and other non-opioid strategies, is partly motivated by the opioid crisis, but it appears to have a practical upside for hospital stays as well. Opioid-sparing strategies have been associated with comparable pain relief, fewer side effects, and shorter stays.²⁷ If your ER team offers IV ketorolac or another NSAID as a first-line option instead of morphine, this is why.

How International Differences Muddy the Numbers

If you search for average hospital stays for kidney stones, you will find numbers that range from hours to nearly a week. Some of that variation reflects genuine differences in stone severity, but a lot of it comes from differences in healthcare systems. Spanish hospital data from 2017 to 2020 showed a median stay of about 5 days for patients hospitalized with kidney or ureteral stones, with an average cost of roughly €3,400 to €3,900 per admission depending on the year.²⁸ That figure is considerably longer than what most U.S. data show for similar procedures, likely reflecting different thresholds for admission, different discharge customs, and the inclusion of patients with metabolic comorbidities that prolonged their stays.

In the U.S., the economic pressure to shorten stays is intense, and the trend toward outpatient and same-day-discharge protocols has moved faster here than in many other countries. If you are reading statistics from a European or Asian healthcare system, the numbers may not match what you would experience at an American hospital, and vice versa. The safest generalization is that the procedure type and your specific complications matter more than any average figure.

1
PubMed. Variation in the Intensity of Care for Patients with Uncomplicated Renal Colic Presenting to U.S. Emergency Departments
2
PubMed Central. Predictors of Hospital Admission and Urological Intervention in Adult Emergency Department Patients with Computerized Tomography Confirmed Ureteral Stones
3
PubMed Central. Size matters: The width and location of a ureteral stone accurately predict the chance of spontaneous passage
4
PubMed. Relationship of spontaneous passage of ureteral calculi to stone size and location as revealed by unenhanced helical CT
5
PubMed. Time to stone passage for observed ureteral calculi: a guide for patient education
6
PubMed. Medical expulsive treatment of distal-ureteral stones using tamsulosin: a single-center experience
7
JAMA Internal Medicine. Effect of Tamsulosin on Passage of Symptomatic Ureteral Stones: A Randomized Clinical Trial
8
Journal of Society of Surgeons of Nepal. Stone Expulsion Rates with Medical Expulsion Therapy vs Expectant Management in 5 to 7 mm Distal Ureteric Stones: A Prospective Comparative Study
9
PubMed Central. Is flexible ureterorenoscopy and laser lithotripsy the new gold standard for lower pole renal stones when compared to shock wave lithotripsy
10
PubMed Central. Day-case rigid and flexible ureteroscopy
11
PubMed Central. Is an overnight stay after percutaneous nephrolithotomy safe?
12
PubMed Central. Review of efficacy and safety of same-day discharge after percutaneous nephrolithotomy
13
PubMed Central. Comparative outcomes and cost of ambulatory PCNL in select kidney stone patients
14
PubMed. Factors Influencing Readmission after Elective Ureteroscopy
15
PubMed. Unplanned Emergency Department Visits and Hospital Admissions Following Ureteroscopy: Do Ureteral Stents Make a Difference?
16
PubMed Central. Ureteral Stent Placement following Ureteroscopy Increases Emergency Department Visits in a Statewide Surgical Collaborative
17
PubMed Central. Risk factors for readmission after ureteroscopy for stone disease: Modern single centre experience
18
PubMed Central. Reasons for early readmission after percutaneous nephrolithotomy and retrograde intrarenal surgery
19
PubMed Central. Unplanned 30-day readmission rates in patients undergoing endo-urological surgeries for upper urinary tract calculi
20
PubMed Central. Disproportionate Use of Inpatient Care by Older Adults With Kidney Stones
21
PubMed. Impact of frailty on clinical outcomes and resource utilization of hospitalizations for renal stone surgery
22
PubMed Central. Complications in Women With Renal Calculi: Increased Risk and Prolonged Hospital Stay
23
PubMed. Clinical presentation and management of urolithiasis in the obstetric patient: a matched cohort study
24
PubMed. Hospitalizations for pediatric stone disease in United States, 2002-2007
25
PubMed. Percutaneous Nephrolithotomy in Children: Analysis of Nationwide Hospitalizations and Short-Term Outcomes for the United States, 2001-2014
26
PubMed. The feasibility of one-day length of hospital stay after pediatric percutaneous nephrolithotomy
27
Pain Management Nursing. Breaking the Stone Cycle: Opioid-Sparing Strategies for Renal Colic Relief
28
PubMed Central. Hospitalization Burden of Patients with Kidney Stones and Metabolic Comorbidities in Spain during the Period 2017–2020