Intestinal Ultrasound Index Calculator

Ulcerative Colitis

Validated intestinal ultrasound activity indices, calculated in real time.

Developed by Dr. J. Poza Cordón · Hospital Universitario La Paz, Madrid · @joaquin_poza

Bowel wall thickness

Shared input for UC-IUS, MUC and IBUS-SAS. One measurement is enough.

UC-IUS

Ulcerative Colitis Intestinal Ultrasound Score · BWT + Doppler + haustration + mesenteric fat

Waiting for data
Scoring, interpretation & references

Total range: 0 to 7 points.

Bowel wall thickness
Measured BWTClinical descriptionFormula contribution
≤2 mmNormal wall thickness+0 points
>2 to ≤3 mmMildly thickened+1 point
>3 to ≤4 mmModerately thickened+2 points
>4 mmMarkedly thickened+3 points
Colour Doppler signal
GradeClinical descriptionFormula contribution
Grade 0Absent or single vessel+0 points
Grade 1Spots+1 point
Grade 2Stretches+2 points
Haustration
GradeClinical descriptionFormula contribution
Grade 0Normal haustration+0 points
Grade 1Abnormal or absent haustration+1 point
Mesenteric fat
GradeClinical descriptionFormula contribution
Grade 0Normal / no fat wrapping+0 points
Grade 1Fat wrapping present+1 point
The BWT thresholds used to award UC-IUS points

Interpretation ranges

ScoreInterpretationPerformance
≤2Endoscopic improvement (MES ≤1) likelySe 67.3%, Sp 91.4%, PPV 85.4%, NPV 79.0%
≥3Active disease — endoscopic improvement unlikelyNot reported
Descriptive BWT correlation with the endoscopic Mayo subscore
Measured BWTInterpretation
≤2.1 mmLikely normal
>2.1 mmCompatible with Mayo ≥1
>3.2 mmCompatible with Mayo ≥2
>3.9 mmCompatible with Mayo 3

References

1Bots S, et al. J Crohns Colitis. 2021.
2Komatsu H, et al. J Gastroenterol. 2025.

MUC

Milan Ultrasound Criteria · 1.4 × BWT + 2 × Doppler

Waiting for data
Scoring, interpretation & references

BWT is entered in millimetres.

GradeClinical descriptionFormula contribution
Grade 0Doppler absent+0.00
Grade 1Doppler present+2.00
MUC is shown with two decimals

Interpretation ranges

Score rangeInterpretationPerformance
≤6.20Ultrasound remission / compatible with endoscopic remissionNot reported
>6.20 to 8.54Endoscopic activitySe 85%, Sp 94%
>8.54 to 10.54Severe ulcerative colitisSe 64%, Sp 93%
>10.54 to 12.50Risk of IV corticosteroid failureSe 50%, Sp 91%
>12.50Risk of colectomySe 56%, Sp 97%

The upper thresholds are cumulative.

References

1Allocca M, et al. United European Gastroenterol J. 2021/2022.
2Yuan B, et al. Eur J Gastroenterol Hepatol. 2024.

IBUS-SAS

International Bowel Ultrasound Segmental Activity Score · capped at 100

Waiting for data
Scoring, interpretation & references

The result is capped at 100.

Colour Doppler signal
GradeClinical descriptionFormula contribution
Grade 0No signal+0
Grade 1Short signals+7
Grade 2Long signals+14
Grade 3Long signals inside and outside the bowel wall+21
Mesenteric fat
GradeClinical descriptionFormula contribution
Grade 0Normal+0
Grade 1Uncertain+15
Grade 2Affected+30
Echostructure
GradeClinical descriptionFormula contribution
Grade 0Normal+0
Grade 1Uncertain+4
Grade 2Focal alteration+8
Grade 3Segmental alteration >3 cm+12
The grade you select is not the number

Interpretation ranges

Score rangeInterpretationPerformance
<15.9Probable remissionNot reported
≥15.9 to <38.4Mild endoscopic activitySe 100%, Sp 80%, AUC 0.97
≥38.4 to <69.2Moderate endoscopic activitySe 78%, Sp 82%, AUC 0.83
≥69.2Severe endoscopic activitySe 67%, Sp 94%, AUC 0.89

References

1Novak KL, et al. J Crohns Colitis. 2020.
2Fischer S, et al. United European Gastroenterol J. 2025.

Final summary

Only indices with all their parameters completed are shown

For use by trained healthcare professionals as a decision-support aid only.

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