ROOS TEST FOR THORACIC OUTLET SYNDROME (TOS) The Roos test has a sensitivity of 84% and a specificity of 30% (Gillard et al. 2001) and stresses all three interfaces (posterior scalene port, costoclavicular space and subcoracoid tunnel) where the brachial plexus can become compressed. (Watson et al. 2010). Watch out as the very low specificity of 30% means that this test will create a high number of false positives! | Physiotutors