Doppler waveform analysis during provocative manoeuvres in the assessment for arterial thoracic outlet syndrome results in high false-positive rates; a cross-sectional study.

Objectives: There is a high rate of false-positive arterial Thoracic Outlet Syndrome (ATOS) diagnoses due to limited research into the optimal use of ultrasound. To improve future diagnostic efficiency, we aimed to characterise the haemodynamic effects of different provocative positions and estimate the prevalence of compression in the healthy population.

Design: In this cross-sectional, observational study, the effect of varying degrees of arm abduction on discomfort levels and/or changes in subclavian artery Doppler waveform was analysed in the healthy population; the peak systolic velocity (PSV), systolic rise time (SRT), phasicity and extent of turbulence were recorded.

Setting: Department of the Vascular Studies, Royal Free Hospital.

Participants: 19 participants (11 females, 27.4 ± 5.2 years) were recruited for bilateral scans.

Main outcome measures: Seven positions were investigated; the primary outcome was an occlusion or monophasic waveform indicating significant compression and this was compared with the secondary outcome; any physiological discomfort.

Results: 28.9% experienced significant arterial compression in at least one position; 120° abduction was the position with the greatest level of abduction that did not result in significant waveform changes or symptoms. The PSV and SRT were difficult to accurately measure and bore no correlation to the level of compression.

Conclusion: Ultrasound testing in isolation would result in a false indication of TOS in almost 30% of our normal population. With further research, the 120° abduction position may have a lower false-positive rate. The PSV and SRT must be interpreted with caution due to their variability even within the healthy population.