- Obtain a brief history: ask about the patient's sex, when the pain started, and whether nausea or vomiting is present.
- Perform a dipstick or microscopic urinalysis and determine whether erythrocytes (blood) are present or absent.
- Select the appropriate option for each of the five variables in the calculator above. Results update automatically — no submit button is needed.
- Interpret the probability category (Low / Moderate / High) in the context of the full clinical picture. A low score should broaden the differential; a high score supports pursuing imaging promptly while keeping serious alternative diagnoses in mind.
- Always arrange physician assessment. The STONE score is a decision-support aid, not a replacement for clinical judgment or imaging.
All computation runs in your browser; no patient data is stored or transmitted.
When to Use
Use the STONE score when evaluating an adult patient presenting to the emergency department or clinic with acute flank pain in whom an uncomplicated ureteral stone is part of the differential diagnosis. The score stratifies patients into low, moderate, and high probability groups to guide the use of diagnostic imaging and downstream management.
Appropriate use
Adult patients presenting with acute unilateral flank pain, where ureteral stone is suspected. The score is most valuable in settings where immediate CT imaging is not available or where pre-test risk stratification is needed to decide between ultrasound-first and CT-first pathways. A high score can support presumptive management while imaging is arranged; a low score should increase suspicion for alternative diagnoses.
When NOT to rely on it
Do not use the STONE score in isolation when red-flag features are present: fever (suggests infected stone), known solitary kidney, haemodynamic instability, or clinical suspicion for abdominal aortic aneurysm. The score was derived and validated in adults presenting to emergency departments in the United States; its performance in paediatric patients and in settings with very different stone prevalence may differ. A low score does not exclude a stone, and a high score does not confirm one — imaging and physician judgment remain essential.
Pearls & Pitfalls
A high score supports stone — but don't stop there
Even a STONE score of 10–13 (high probability, ~88–89% stone likelihood) means roughly 1 in 10 patients does not have a stone. Always consider serious alternative diagnoses, particularly abdominal aortic aneurysm in older patients with vascular risk factors and atypical pain characteristics. A high score supports prompt imaging; it does not replace it.
Urinalysis timing matters
Microscopic hematuria is absent in up to 15–30% of patients with a confirmed ureteral stone. Collect the urine early in the visit, before IV fluids are given, to maximise sensitivity. A negative dipstick does not exclude a stone — it simply scores zero for the erythrocytes variable, shifting the total toward a lower risk band.
Seek emergency care immediately for these features
Fever or rigors, a single functioning kidney, uncontrolled pain despite analgesia, persistent vomiting preventing oral hydration, or reduced urine output all indicate a potentially obstructed or infected stone — a urological emergency. Do not wait for imaging results before initiating urgent assessment. These features are exclusions from routine outpatient stone management regardless of the STONE score.
Why Use It
Acute flank pain is one of the most common emergency department presentations, yet the diagnosis of ureteral stone is not always straightforward. CT urography is the gold-standard imaging modality but exposes patients to ionizing radiation, incurs cost, and may not be immediately available in all Philippine settings. Ultrasound has lower sensitivity but avoids radiation and is widely accessible.
The STONE score (Sex, Timing, Origin, Nausea/vomiting, Erythrocytes) was derived and validated by Moore et al. in a multicenter US emergency department cohort (BMJ 2014). In the validation cohort, a score of 0–5 (low) corresponded to approximately 9–10% stone likelihood, score 6–9 (moderate) to approximately 51%, and score 10–13 (high) to approximately 88–89%. By quantifying pre-imaging probability, the score helps clinicians decide which patients can safely proceed with ultrasound-first protocols versus those who benefit from immediate CT, and which low-probability patients need thorough evaluation for serious alternative causes of flank pain such as aortic aneurysm, pyelonephritis, or gynaecologic pathology.
In the Philippine context, where radiation exposure, cost, and after-hours CT availability are genuine constraints, a validated pre-test probability tool adds practical value at the point of care.
STONE Score — Ureteral Stone Likelihood Calculator
Select the five clinical variables below. The score and probability category update automatically.
⚕ Based on Moore CL, et al. Derivation and validation of a clinical prediction rule for uncomplicated ureteral stone — the STONE score. BMJ 2014;348:g2191. Score range 0–13. Low: 0–5 (~9–10% stone likelihood). Moderate: 6–9 (~51%). High: 10–13 (~88–89%). A low score does not exclude a stone; a high score does not confirm one or rule out serious alternative causes of flank pain. Always be evaluated by a physician.
Next Steps
Use the result to support — not replace — clinical judgment.
- Interpret the value against the targets shown in the calculator and the Evidence section below, in the context of the full clinical picture.
- Trend serial measurements rather than acting on a single result; confirm abnormal or unexpected values before changing management.
- Apply the relevant KDIGO / specialty-guideline threshold and document the indication.
- Escalate or refer to nephrology when results are out of range, rapidly changing, or discordant with the clinical picture — and discuss the implications with the patient.
Evidence & References
Formula & Equations
| Variable | Finding | Points |
|---|---|---|
| Sex | Male | +2 |
| Sex | Female | 0 |
| Timing (duration of pain) | Less than 6 hours | +3 |
| Timing (duration of pain) | 6 to 24 hours | +1 |
| Timing (duration of pain) | More than 24 hours | 0 |
| Origin (race/ethnicity) | Non-Black | +3 |
| Origin (race/ethnicity) | Black | 0 |
| Nausea / vomiting | Vomiting | +2 |
| Nausea / vomiting | Nausea alone | +1 |
| Nausea / vomiting | None | 0 |
| Erythrocytes (urinalysis) | Present | +3 |
| Erythrocytes (urinalysis) | Absent | 0 |
Risk Bands
| Category | Score Range | Approximate Stone Likelihood |
|---|---|---|
| Low | 0–5 | ~9–10% |
| Moderate | 6–9 | ~51% |
| High | 10–13 | ~88–89% |
Maximum possible score: 13 (Male +2, timing <6 h +3, non-Black +3, vomiting +2, hematuria present +3). Likelihood estimates are from the validation cohort (Moore et al. 2014, BMJ); actual prevalence may vary by setting and population.
Evidence & References
The STONE score was derived and validated by Moore et al. in a prospective multicenter emergency department study published in the BMJ in 2014. The acronym stands for Sex, Timing, Origin, Nausea/vomiting, and Erythrocytes. The score demonstrated good discrimination (AUC ~0.86) between patients with and without confirmed ureteral stones on CT urography. Subsequent studies have examined stone size and spontaneous passage rates (Coll et al.), and the EAU Urolithiasis Guidelines provide the current international framework for stone management including imaging decision pathways.
- Moore CL, Bomann S, Daniels B, et al. Derivation and validation of a clinical prediction rule for uncomplicated ureteral stone — the STONE score: retrospective and prospective observational cohort studies. BMJ. 2014;348:g2191.
- Coll DM, Varanelli MJ, Smith RC. Relationship of spontaneous passage of ureteral calculi to stone size and location as revealed by unenhanced helical CT. AJR Am J Roentgenol. 2002;178(1):101–103.
- EAU Guidelines on Urolithiasis 2024. European Association of Urology; 2024.
