How Do They Check For Kidney Stones? What You Need to Do

Kidney stones are diagnosed through a combination of your medical history, a physical exam, urine and blood tests, and imaging scans that can actually see the stone. The most common imaging test is a non-contrast CT scan, which finds stones with high accuracy and shows their size and location. If you have classic symptoms — severe flank pain that comes in waves, blood in the urine, nausea — your doctor can often narrow things down quickly, but imaging is what confirms it.

How Do They Check For Kidney Stones?

The process usually starts with questions and a physical exam, then moves to lab work and imaging. No single test does everything. Each one answers a different question: Is there a stone? How big is it? Where is it stuck? Is it blocking urine flow? Is there an infection?

Your doctor will ask about the pain — where it started, how it moves, how intense it gets. Kidney stone pain often begins in the back or side and radiates toward the groin as the stone travels down the ureter, the tube connecting the kidney to the bladder. That pattern is distinctive enough that it raises suspicion right away.

Then come the tests. Urinalysis checks for blood, infection, and crystals. Blood tests look at kidney function and levels of substances like calcium and uric acid. Imaging confirms the diagnosis and guides treatment.

One thing worth knowing: not every kidney stone causes symptoms. Some are found by accident during imaging done for unrelated reasons. These “silent” stones may never need treatment, depending on their size and location.

What Imaging Tests Are Used to Find Kidney Stones?

Imaging is the only way to confirm a kidney stone with certainty. Several options exist, and the choice depends on your situation — pregnancy, age, how many scans you’ve had before, and what your doctor needs to see.

Non-contrast CT scan is the standard first choice for most adults. It takes minutes, requires no dye injection, and detects nearly all stones regardless of their composition. It also shows whether a stone is blocking the ureter and how much the kidney is swelling. The main downside is radiation exposure, though the dose from a single stone-protocol CT is relatively low compared to older scanners.

Ultrasound is often used first in pregnant women and children because it uses no radiation. It can detect stones in the kidney and show hydronephrosis — swelling from backed-up urine. Its weakness is that it may miss small stones in the ureter, especially in the middle portion. If ultrasound is inconclusive, further imaging may be needed.

X-ray of the kidneys, ureters, and bladder (KUB) can show larger stones that contain calcium. It misses uric acid stones entirely and is less sensitive than CT. It’s sometimes used for follow-up rather than initial diagnosis.

Intravenous pyelogram (IVP) uses contrast dye and X-rays to show how urine flows. It’s rarely used now that CT is widely available.

Your doctor picks the test based on your specific circumstances. There is no universal “best” test for everyone.

What Do Blood and Urine Tests Show?

Lab tests don’t usually find the stone itself, but they reveal a lot about what’s happening in your body and why the stone formed.

A urinalysis checks for red blood cells, which are present in most people with kidney stones even if the urine looks normal. It also detects white blood cells (a sign of infection), crystals, and abnormal pH. If infection is present alongside a blocked stone, that’s a medical emergency requiring urgent treatment.

Blood tests measure kidney function (creatinine and BUN), calcium, uric acid, and electrolytes. High calcium or high uric acid can point to a metabolic cause. Kidney function matters because a blocked ureter can reduce how well the kidney filters waste.

If you’ve had more than one stone, your doctor may order a 24-hour urine collection. You collect all urine over a full day, and the lab measures volume, acidity, and levels of stone-forming substances like calcium, oxalate, citrate, and uric acid. This test helps identify why you keep forming stones and guides prevention. It is not typically done after a first stone unless there are strong reasons.

What Happens After a Stone Is Found?

Finding the stone is only part of the picture. Size, location, and whether it’s blocking urine flow determine what happens next.

Stones smaller than 5 millimeters often pass on their own within a few weeks. Stones between 5 and 10 millimeters may pass but are less likely to do so without help. Stones larger than 10 millimeters usually need a procedure. These thresholds come from established urological guidelines and are widely used in clinical practice.

If the stone is blocking the ureter and causing severe pain, infection, or reduced kidney function, urgent intervention is needed. Options include:

• Shock wave lithotripsy (SWL): Sound waves break the stone into smaller pieces that pass in urine. Best for stones in the upper ureter or kidney that are not too hard.
• Ureteroscopy: A thin scope passes through the urethra and bladder into the ureter. The stone is removed or broken up with a laser. Works well for stones in the ureter and kidney.
• Percutaneous nephrolithotomy (PCNL): A small incision in the back allows direct access to large kidney stones. Used for stones that are too large for other methods.

Your urologist will recommend based on stone size, location, your anatomy, and your health. There is no single right answer for every case.

When Should You Seek Medical Attention?

Severe flank pain that comes in waves and won’t go away is the main signal to get checked. Other signs that warrant prompt attention include blood in the urine, fever, chills, nausea and vomiting that prevent you from keeping fluids down, and pain so intense you can’t sit still.

Fever combined with flank pain is especially concerning. It can mean an infected, blocked kidney — a condition that requires emergency treatment. Do not wait to see if it improves on its own.

If you’ve had a stone before, you know the pain pattern. But don’t assume every episode is the same. A stone that has moved or grown can cause different symptoms. And not all flank pain is a kidney stone — muscle strain, urinary tract infections, and other conditions can feel similar.

Can You Check for Kidney Stones at Home?

No. There is no home test that can confirm a kidney stone. Home urine test strips can detect blood or infection, but blood in the urine has many causes and does not prove a stone is present.

Some people try to “wait it out” at home, drinking fluids and taking over-the-counter pain relievers. That approach is reasonable for small stones if pain is manageable and you can keep fluids down. But if pain is severe, if you have fever, or if you can’t urinate, you need medical care.

There’s no diet, supplement, or home remedy that dissolves a kidney stone once it has formed. Some medications can help certain types of stones pass or prevent new ones, but those require a diagnosis and a prescription.

What to Expect During Diagnosis

The diagnostic process is usually fast. If you go to an emergency department with classic symptoms, you may have a CT scan within hours. If you see your doctor for milder symptoms, the workup may take a few days.

You may not get a definitive answer at the first visit. Sometimes imaging is inconclusive, especially with ultrasound. Sometimes a stone has already passed by the time you’re seen, and the diagnosis is made based on symptoms and lab results alone. That’s normal.

The key takeaway: kidney stones are diagnosed through a combination of history, exam, lab tests, and imaging. No single test is perfect. Your doctor uses all the information together to make the call.