Know to Prevail
Menu

Screenings by age and gender

Kidney stone found by chance: follow-up

A CT or ultrasound done for another reason sometimes shows a kidney stone that has caused no pain or other symptoms. Guidance notes that more of these stones are found now that scans are more common. (Tuo 2026) This page covers how such a stone is usually watched and which tests look for a cause, not how stones are removed, diet, fluids or medicines.

The main guidance

  • European Association of Urology (EAU) Guidelines on Urolithiasis (2026 edition): covers observation of stones that cause no symptoms, the basic tests for every stone patient and the extra tests for people at high risk. (EAU 2026)(EAU 2026, ch. 4)
  • NICE renal and ureteric stones guideline NG118 (England, 2019): covers watchful waiting for stones without symptoms and the blood test for calcium. (NICE NG118)
  • American Urological Association (AUA) medical management guideline (2014): covers a screening evaluation for people with a first stone and a fuller metabolic evaluation for selected people. (AUA 2014)

Who it applies to

Adults whose scan, done for another reason, shows a stone in the kidney that is not blocking urine flow and has caused no symptoms. The EAU guideline says stones affect 1% to 13% of people, depending on where they live, climate, diet and genes. (EAU 2026) A stone stuck in the tube from the kidney (ureter), or one causing pain, fever or blocked urine, is a different situation handled straight away by your care team.

How a stone without symptoms is watched

Watching a kidney stone that causes no symptoms (simplified)
GuidanceWhat it says
NICE 2019 (NICE NG118)Consider watchful waiting if the stone is under 5 mm, or larger than 5 mm if the person agrees after talking through the possible risks and benefits. No follow-up interval is set.
EAU 2026 (EAU 2026)One trial supports a yearly check for stones under 10 mm in the lower part of the kidney; if the stone grows, the gap between checks should be shorter. The guideline says this is not backed by high-level evidence.
EAU 2026, follow-up chapter (EAU 2026, ch. 5)Follow-up imaging is a plain X-ray of the kidneys, ureters and bladder and/or an ultrasound; CT is kept for symptoms or for planning a procedure, to avoid extra radiation. (This chapter is written for people after treatment.)

What happens to these stones over time

  • In a US study, 160 stones without symptoms were watched for an average of 41 months: 28% caused symptoms, 7% passed on their own, and 3 stones (2%) blocked urine flow without pain. The authors say regular follow-up imaging found these in time to prevent loss of the kidney. (Dropkin 2015)
  • In a Chinese study of 293 people with yearly ultrasound for an average of 4.2 years, 32% of stones passed on their own, 17% grew, 28% caused symptoms and 12% needed a procedure. Stones over 5 mm, stones outside the lower part of the kidney, diabetes and high uric acid were linked to more events. (Li 2019)
  • The EAU guideline sums up a review of such studies: stones passed on their own in 3% to 29%, caused symptoms in 7% to 77%, grew in 5% to 66% and needed a procedure in 7% to 26%. (EAU 2026)

Tests that look for a cause

  • Blood calcium. NICE says to measure serum calcium in adults with kidney stones, because a raised level can point to primary hyperparathyroidism. (NICE NG118) See checks if you have primary hyperparathyroidism.
  • Basic blood and urine tests. The EAU guideline lists creatinine, uric acid, calcium, sodium, potassium, a blood count and C-reactive protein, plus a urine dipstick and microscopy or culture; when no procedure is planned, sodium, potassium and C-reactive protein can be left out. (EAU 2026) See kidney test results, metabolic panel results and urinalysis results.
  • Stone analysis. If a stone passes, NICE says to consider analysing it and the EAU recommends it for a first stone, because the stone type guides any further tests. (NICE NG118)(EAU 2026)
  • 24-hour urine collection. The EAU guideline says only people at high risk of more stones need this fuller check, done as two 24-hour collections. (EAU 2026, ch. 4) The AUA guideline also limits the fuller metabolic evaluation to selected people. (AUA 2014)

The EAU high-risk list includes, among others, stones starting in childhood or the teens, stones in the family, repeat stones, a single working kidney, chronic kidney disease, hyperparathyroidism, polycystic kidney disease, some bowel conditions and bowel surgery, and some inherited conditions. (EAU 2026) See screenings for people with polycystic kidney disease.

What changes the plan

The EAU guideline lists these as reasons to think again about a stone rather than keep watching: (EAU 2026)

  • The stone grows, or starts to block urine flow
  • An infection, or symptoms such as pain or blood in the urine
  • A high risk of forming more stones (see the list above)
  • Other illnesses, the person's own wishes, and their job or travel

It also says a single kidney is a reason for urgent imaging if symptoms start. (EAU 2026)

Signs of kidney stones that need a doctor's help, from MedlinePlus: (MedlinePlus)

  • Extreme pain in your back or side that will not go away
  • Blood in your urine
  • Fever and chills
  • Vomiting
  • Urine that smells bad or looks cloudy
  • A burning feeling when you urinate

Routine age-based screening

A finding on a scan does not replace the routine screenings for your age; see screenings by age and gender.

Where they differ:

  • Size and timing. NICE uses a 5 mm line for watchful waiting and sets no interval. (NICE NG118) The EAU describes yearly checks for lower kidney stones under 10 mm, and says it is still debated whether stable stones should be treated or simply checked each year. (EAU 2026)
  • 24-hour urine. The EAU recommends it for people at high risk. (EAU 2026, ch. 4) NICE found no evidence for it, made no practice recommendation and asked for research instead. (NICE NG118)
  • Watching versus acting. A 2026 review of 6 trials (592 people) found that acting on a stone early cut later procedures, but the authors say the evidence is limited and the choice should be made together, not as a routine for every stone. (Tuo 2026)

Your doctor decides what your result means for you.

Questions people ask

Is a kidney stone found on a scan something to worry about?

Often not right away. In a US study of 160 stones that caused no symptoms and were watched for an average of over 3 years, most stayed without symptoms, fewer than 30% caused pain and 7% passed on their own. (Dropkin 2015)

How often will I need another scan?

There is no agreed schedule. The EAU guideline says one trial supports a yearly check for small stones in the lower part of the kidney, with shorter gaps if the stone grows; NICE does not set an interval. Your doctor decides. (EAU 2026) (NICE NG118)

Will the next scan be a CT?

Not usually. For follow-up, the EAU guideline suggests a plain X-ray and/or an ultrasound and keeps CT for symptoms or for planning a procedure, to limit radiation. (EAU 2026, ch. 5)

Which blood and urine tests might I have?

NICE says to measure blood calcium in adults with kidney stones. The EAU guideline lists a basic set of blood tests and a urine dipstick for all stone patients, and two 24-hour urine collections only for people at high risk of more stones. (NICE NG118) (EAU 2026) (EAU 2026, ch. 4)

What would change the plan?

The EAU guideline lists stone growth, blockage, infection, symptoms such as pain or blood in the urine, a high risk of more stones, other illnesses, the person's wishes and their job or travel. (EAU 2026)

Related