Definitions of severity grades (0–3) for each elementary component and for the EULAR-OMERACT combined score
| Synovitis | SH (greyscale) | Doppler (PD) | Combined score* (greyscale SH + PD) |
| Grade 0 (normal) | No SH independently of the presence of effusion | No Doppler signal | No SH and no PD signal |
| Grade 1 (minimal) | Minimal hypoechoic SH* up to the level of the horizontal line connecting bone surfaces between the metacarpal head and the proximal phalanx | Up to three single Doppler spots OR up to one confluent spot and two single spots OR up to two confluent spots | Grade 1 hypoechoic SH and ≤ grade 1 PD signal |
| Grade 2 (moderate) | Moderate hypoechoic SH† extending beyond joint line but with the upper surface concave (curved downwards) or hypertrophy extending beyond the joint line but with the upper surface flat | >Grade 1 but <50% Doppler signals in the total greyscale background | Grade 2 hypoechoic SH and ≤ grade 2 PD signal; or grade 1 SH and a grade 2 PD signal |
| Grade 3 (severe) | Severe hypoechoic SH† with or without effusion extending beyond the joint line but with the upper surface convex (curved upwards) | >Grade 2 (>50% of the total greyscale background) | Grade 3 hypoechoic SH and ≤ grade 3 PD signal; or grade 1 or 2 SH and a grade 3 PD signal |
*EULAR-OMERACT combined score.
† Independently of the presence of effusion.
EULAR-OMERACT, European League Against Rheumatisms–Outcomes Measures in Rheumatology; PD, power Doppler; SH, synovial hypertrophy.