Ureteric Stone Spontaneous Passage Interpreter
Ureteric Stone Spontaneous Passage Interpreter
The published proportions of ureteric stones that passed spontaneously, by size and by location, read straight off the EAU’s own figures — 49 to 52 per cent in the upper ureter against 68 to 83 per cent in the distal, and 89 per cent for a distal stone under 5 mm.
What proportion passed, by size and site
Size + location → published proportionsA 4 mm stone in the distal ureter on a non-contrast CT
What the proportions are, and what they are not
By size — almost 75% of stones under 5 mm · 62% of stones 5 mm and larger
Size and location together — under 5 mm distal 89% · under 5 mm upper 71%
Average time to expulsion 17 days, range 6 to 29
- these are proportions, not predictions
- A score, an index, a measured volume or an attenuation value is not a diagnosis, and a proportion measured in a cohort is not a probability for one patient. An 89 per cent figure means that 89 per cent of a published cohort’s stones passed. It does not say which. The EAU states directly that the panel is aware spontaneous expulsion decreases with increasing stone size and that there are differences between individual patients
- only two size-and-location figures exist
- under 5 mm in the distal ureter and under 5 mm in the upper ureter. The EAU says in terms that “there are only limited data regarding spontaneous stone passage according to stone size”. For a mid-ureteral stone, or for a 5 mm-and-over stone at a named level, this page quotes the two separate strata the stone belongs to rather than multiplying or interpolating them into a number nobody published
- the strata are linear, and burden is not
- the published strata are cumulative linear diameter — under 5, 5 to 10, 10 to 20 and over 20 mm — so a linear diameter is the right input here. That is not a contradiction of the stone volume page: burden scales as a cube, which is why volume predicts stone-free status after surgery better than diameter, while the passage literature happens to be stratified linearly
- observation is not inaction
- the EAU’s summary of evidence states that observation is feasible in informed patients who develop no complications — infection, refractory pain, deterioration of renal function — and its recommendation is to observe with periodic evaluation. Those three complications are the conditions on the whole page, and none of them is something a proportion can predict. This page reports a figure and what the published sources attach to it. It does not make a clinical decision and cannot.
- the panel and the stone-risk work are elsewhere
- The 24-hour urine stone-risk panel and its interpretation already live in the urine chemistry category and are not rebuilt here. A stone that has passed is a stone to investigate: the 24-hour urine stone-risk interpreter reads a 24-hour collection against the EAU’s limits, and the urine collection adequacy calculator, urine calcium converter, urine citrate converter, urine oxalate converter, urine uric acid converter and urine creatinine converter are the panel it reads
Worked example
A 4 mm stone in the distal ureter on a non-contrast CT
4 mm is at or below the AUA's 10 mm limit for offering observation, so the page does not stop there
4 mm is under 5 mm and the location is distal — the most favourable of the two size-and-location combinations the EAU publishes
The published proportion is 89 per cent, against 71 per cent for the same size in the upper ureter and 68 to 83 per cent for the distal ureter at all sizes
Average time to expulsion across the pooled series was 17 days with a range of 6 to 29 days. The AUA suggests definitive treatment be offered if observation has not succeeded after four to six weeks
Move the same stone to the upper ureter and the proportion falls to 71 per cent. Grow it to 6 mm and there is no distal figure at all for that size — only the 68 to 83 per cent for the location and the 62 per cent for stones 5 mm and larger, which is why this page reports two numbers rather than one there
The published passage proportions
| Stratum | Proportion that passed spontaneously | Source |
|---|---|---|
| Upper (proximal) ureter, all sizes | 49 to 52 per cent | EAU urolithiasis guideline, section 3.4.9.a |
| Mid ureter, all sizes | 58 to 70 per cent | The same section |
| Distal ureter, all sizes | 68 to 83 per cent | The same section |
| Under 5 mm, any location | Almost 75 per cent | The same section |
| 5 mm and larger, any location | 62 per cent | The same section |
| Under 5 mm, distal ureter | 89 per cent | The same section |
| Under 5 mm, upper ureter | 71 per cent | The same section |
| Time to expulsion | Average 17 days, range 6 to 29 days | The same section |
The equivalent figures for a renal stone left alone
| Outcome over active surveillance | Range across the systematic review |
|---|---|
| Spontaneous stone passage | 3 to 29 per cent |
| Symptom development | 7 to 77 per cent |
| Stone growth | 5 to 66 per cent |
| Surgical intervention | 7 to 26 per cent |
| Where intervention is advised | The EAU advises intervention for growing stones above 5 mm, and notes a prospective trial supporting annual observation for asymptomatic inferior calyceal stones under 10 mm |
Location matters more than size, and only two cells have both
The question a patient with renal colic asks first is whether the stone will pass, and the honest answer is a proportion from a cohort. The EAU’s urolithiasis guideline publishes those proportions by location: 49 to 52 per cent of upper ureteral stones, 58 to 70 per cent of mid-ureteral stones and 68 to 83 per cent of distal ones passed spontaneously. Location is the strongest single factor on the page — roughly a doubling from the upper to the distal ureter — and it is the one factor nothing can change.
Size matters too, and the data are thinner than the confidence with which size is usually quoted. The guideline gives almost 75 per cent for stones under 5 mm and 62 per cent for stones of 5 mm and larger, and then states plainly that “there are only limited data regarding spontaneous stone passage according to stone size”. Exactly two figures combine size with location: 89 per cent for a stone under 5 mm in the distal ureter and 71 per cent for one under 5 mm in the upper ureter. For a mid-ureteral stone, or for anything 5 mm and over at a named level, this page reports the two separate strata the stone belongs to rather than combining them — multiplying or interpolating between published strata produces a plausible number nobody has measured, and that is the error this whole project is built to avoid.
Above 10 mm there is nothing to report. The AUA and Endourological Society guideline offers observation for uncomplicated ureteral stones of 10 mm or less, a strong recommendation at evidence grade B, and suggests definitive treatment be offered if observation has not succeeded after four to six weeks or sooner by shared decision-making. The EAU publishes no passage proportion for larger stones. The two guidelines also disagree about what can be quoted at all: the AUA publishes no proportion anywhere and says in its own future-directions section that clinicians’ ability to counsel patients on how long a stone will take to pass is limited. That disagreement is printed here rather than reconciled.
Three things to carry away. The average time to expulsion in the pooled series was 17 days with a range of 6 to 29 days, so a stone that has not passed in a fortnight is not yet unusual. Observation is conditional, not passive: the EAU’s own framing is that it is feasible in informed patients who develop no complications — infection, refractory pain or deterioration of renal function — with periodic evaluation, and none of those three is predictable from a proportion. And the stone’s own measurement is shakier than the strata suggest, with three radiologists differing by an average of 26.3 per cent on the same stone in one series, which matters most either side of the 5 mm boundary; the stone volume page covers that, and the attenuation page covers what the CT density does and does not say about composition. The 24-hour urine stone-risk panel and its interpretation already live in the urine chemistry category and are not rebuilt here.
Frequently asked questions
Will a 4 mm stone pass on its own?
In the EAU’s pooled series, 89 per cent of distal stones under 5 mm and 71 per cent of upper ureteral stones under 5 mm passed spontaneously. That is a proportion observed in a cohort, not a prediction for one stone — the guideline adds that expulsion decreases with increasing size and that there are differences between individual patients.
How long does a ureteric stone take to pass?
The EAU reports an average time to expulsion of about 17 days with a range of 6 to 29 days. The AUA suggests definitive treatment be offered if observation has not succeeded after four to six weeks, and states separately that clinicians’ ability to counsel patients on how long a stone will take is limited.
Why does the page give two numbers for some stones?
Because only two published figures combine size with location — under 5 mm distal and under 5 mm upper. For every other combination the guideline publishes a location-specific proportion and a size-specific proportion separately, so both are quoted. Combining them into one number would invent a figure nobody measured.
Why is there no answer above 10 mm?
Because neither guideline supplies one. The AUA offers observation for uncomplicated ureteral stones of 10 mm or less and makes no observation recommendation above that, and the EAU publishes no passage proportion for larger stones. Printing a number there would mean extrapolating off the end of the published data.
Does location really matter more than size?
On these figures, yes. The spread by location at all sizes is 49 to 52 per cent to 68 to 83 per cent — roughly a doubling — while the spread by size is 75 per cent against 62 per cent. Both matter; the location data are also the more complete of the two.
What this page will not tell me
Every threshold, range and performance figure on this page is the published figure from the source named beside it, and each one depends on the population, the method and the equipment it was derived in. Where your own report, laboratory or local guideline gives a different figure, that figure governs. A score, an index, a measured volume or an attenuation value is not a diagnosis, and a proportion measured in a cohort is not a probability for one patient. This page reports a figure and what the published sources attach to it. It does not make a clinical decision and cannot.
Related calculators
References
- European Association of Urology. Guidelines on Urolithiasis, 2026 edition — Guidelines chapter, including the cumulative-diameter size strata, the spontaneous passage proportions in section 3.4.9.a and the shockwave-lithotripsy attenuation statement. uroweb.org.
- American Urological Association / Endourological Society. Surgical Management of Stones guideline — observation is offered for uncomplicated ureteral stones of 10 mm or less, with definitive treatment offered if observation has not succeeded after four to six weeks. auanet.org.
- The future of urolithiasis measurement: determining stone volume. AUANews. May 2024 — the published overestimates of the best-fit ellipsoid formulas and the interobserver error in linear measurement.
Not medical advice. For healthcare professionals and education. Reference intervals vary by laboratory and assay — always use your own laboratory's. Never base a dose or a treatment decision on this page alone. Full disclaimer at calcengines.com/disclaimer/