Objective To assess Doppler ultrasound (US) and tenosynovial fluid (TSF) characteristics in tenosynovitis within common rheumatic conditions, as well as their diagnostic utility.
Methods Subjects with tenosynovitis underwent Doppler US and US-guided TSF aspiration for white cell count (WCC) and crystal analysis. Tenosynovial Doppler scores (DS) were semiquantitatively graded. TSF WCC and DS were compared using Kruskal-Wallis tests and logistic regression between non-inflammatory conditions (NIC), inflammatory conditions (IC) and crystal-related conditions (CRC). Receiver operating curves, sensitivity and specificity assessed the ability of WCC and DS to discriminate IC from NIC.
Results We analysed 100 subjects from 14 sites. The mean age was 62 years, 65% were female, and the mean TSF volume was 1.2 mL. Doppler signal was present in 93.7% of the IC group and was more frequent in IC than in NIC group (OR 6.82, 95% CI 1.41 to 32.97). The TSF median WCC per 109/L was significantly higher in the IC (2.58, p<0.001) and CRC (1.07, p<0.01) groups versus the NIC group (0.38). A TSF cut-off of ≥0.67 WCC per 109/L optimally discriminated IC versus NIC with a sensitivity and specificity each of 81.3%. In the IC group, 20 of 48 (41.7%) subjects had a TSF WCC <2.00 per 109/L.
Conclusions A negative DS helps rule out IC in tenosynovitis, but a positive DS is non-specific and merits TSF testing. Unlike synovial fluid, a lower TSF WCC better discriminates IC from NIC. US guidance facilitates aspiration of minute TSF volume, which is critical for diagnosing tenosynovial CRC.
- synovial fluid
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Handling editor Josef S Smolen
Presented at This study has been partially presented as a poster at the 2018 American College of Rheumatology annual meeting and as an oral presentation at the 2019 American College of Rheumatology annual meeting.
Contributors All authors contributed to this manuscript and gave approval to the final version.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.
Patient consent for publication Not required.
Ethics approval All study sites had institutional review board approval.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data are available upon reasonable request. Data requests should be sent to EYK.