THORACIC OUTLET SYNDROME (TOS) ⠀ [PATHOLOGY & DIAGNOSIS] ⠀ This video (Venogram) is an amazing follow up to my TOS series I posted a few weeks ago! It describes a patient with venous TOS: Provocative test shows right subclavian compression and compromised venous return. ⠀ TOS is a term used to describe a group of disorders that occur when there is compression, injury or irritation of the nerves and/or blood vessels (arteries and veins) in the lower neck and upper chest area. TOS is named for the