How this instrument works
Four fields, each contributing a fixed number of points. Sex scores 2 for male, 0 for female. Timing from pain onset to presentation scores 0 for 24 hours or more, 1 for 6 to 24 hours, and 3 for under 6 hours — sudden severe onset reads as more typical of a passing stone than a slow-building ache. Nausea and vomiting scores 0 for neither, 1 for nausea alone, and 2 for vomiting. Hematuria, blood in the urine, scores 0 if absent and 3 if present. The four add together for a total between 0 and 10 on this version of the instrument.
Moore, Bomann, and colleagues derived and validated the rule in a 2014 BMJ paper, drawing on a retrospective cohort to build it and a separate prospective cohort to confirm it held up, in patients presenting to an emergency department with flank pain who went on to get a CT scan. The goal was narrow and practical: identify which patients are likely enough to have an uncomplicated stone, and unlikely enough to have something more dangerous, that skipping the scan becomes a reasonable option rather than a gamble.
This calculator implements four of the five criteria from the original published instrument — see the FAQ below for exactly what's been left out and why. That omission means the total here tops out at 10 rather than the original's 13, and the result should be read as this site's deliberately adapted version, not a letter-for-letter reproduction of the 2014 rule.
- Select Sex — male scores 2 points, female scores 0, reflecting the sex-based difference in stone incidence observed in the derivation cohort.
- Select how long ago the pain began: 24 hours or more (0 points), 6 to 24 hours (1 point), or under 6 hours (3 points).
- Select Nausea/vomiting: neither (0), nausea only (1), or vomiting (2).
- Select Hematuria: absent (0) or present (3), then read the total out of a possible 10.
Worked example — male, under 6 hours, vomiting, hematuria
A male patient scores 2. He presented under 6 hours after pain onset, adding 3. He's had vomiting rather than nausea alone, adding 2. His urine shows hematuria, adding 3. Total: 2 + 3 + 2 + 3 = 10 out of the possible 10 on this four-criterion version — the maximum score, a picture strongly in favor of an uncomplicated ureteral stone.
A female patient presenting 24 or more hours after onset, with no nausea or vomiting and no hematuria, scores 0 + 0 + 0 + 0 = 0, the floor of this scale.
A third patient — male (2), presenting 6 to 24 hours out (1), with nausea only (1), and no hematuria (0) — totals 4, a middling result that leans on the treating clinician's judgment rather than settling the question by itself.
Questions
Why does this calculator drop one of the original STONE score's five criteria?
The original 2014 instrument included a fifth criterion, 'Origin,' worth up to 3 points based on race: non-Black patients scored 3, Black patients scored 0, reflecting a lower observed stone incidence among Black patients in the derivation cohort. This calculator leaves that criterion out entirely. A race-based input to a clinical score has drawn legitimate criticism as an oversimplified and potentially inequitable proxy, and in 2024 Moore and colleagues published a separate 'New STONE score' that replaces Origin with a race-free criterion and reports comparable accuracy — that paper is cited below as a related development, though this calculator doesn't reproduce its exact substitution either; it simply omits Origin outright. Either way, dropping a validated criterion means the total here runs 0 to 10 rather than the original's 0 to 13, and this instrument should be treated as an adapted subset, not the published rule in full.
How is the STONE score meant to be used in practice?
As a rough triage aid, not a diagnosis. A low total argues against an uncomplicated stone being the explanation for flank pain and toward considering alternative diagnoses or further workup; a high total argues that a stone is likely enough that some clinicians will treat conservatively without a CT. The score informs that conversation — it doesn't replace clinical judgment or a physical exam.
Why do men score points just for being male?
Because the derivation cohort observed a higher rate of confirmed ureteral stones among men than women, and the score is built entirely from statistical associations found in that data, not from a theory about anatomy. Sex functions here as a population-level probability marker, the same way age or timing does, rather than a claim about any individual case.
Why does faster onset of pain score more points than a slow build-up?
Because a stone lodging in the ureter classically causes sudden, severe colicky pain, while pain that develops gradually over a day or more is statistically more likely to trace back to a different cause. The 3-point jump for under-6-hours reflects how strongly that pattern showed up in the original cohort's confirmed-stone cases.
Can this score replace a CT scan on its own?
No single number should. The STONE score was validated to help decide who might reasonably skip imaging, not to certify a diagnosis outright — a very high or very low total still sits inside a probability range, and the original study reported it alongside, not instead of, standard emergency evaluation.
References
- Moore CL, Bomann S, Daniels B, et al., 2014 — BMJ, original derivation (PubMed)
- Moore CL, Gross CP, Hart L, et al., 2024 — race-free 'New STONE score,' JACEP Open (PMC)
Read this first: This instrument computes a screening figure from population formulas — it is not a diagnosis, and it cannot see the whole picture a clinician can. Use it to inform a conversation, not to replace one.