Palpating the first dorsal compartment will reveal a swelling, painful and sore area. To locate the first dorsal compartment, move the thumb into abduction and observe the tendons of APL and EPB forming the radial-palmar limit of the snuffbox. Follow these tendons proximally with your index finger to where they become secured to the radius just proximal to the radial styloid, which are held in place by a fibro-osseous sheath. 
A special test to detect de Quevain’s tenosynovitis is the Finkelstein’s test. This test should be done actively by the patient and passively by the physical therapist. The patient’s thumb is grasped in the palm with the fingers of the same hand; then the wrist is deviated in the ulnar direction. A positive test result is a sharp pain felt in the region of the first dorsal compartment. Pain on resisted thumb abduction or extension should also be assessed. 
The physical therapist should be carefull to distinguishing the de Quervain’s Syndrome, which the pain is located over the de Quervain’s tunnel near the end of the radius bone, from the intersection syndrome, which the pain is located over the intersection point on the wrist, about three inches up the forearm. 
Physical therapy treatment involves massage and soft-tissue mobilization to reduce the swelling, deep tissue massage and myofascial release techniques to reduce the inflammation of the tendons and of the tenosynovium, strengthening and stretching of the APL and EPB tendons, mobilization of the surrounding joints, and icing. The patient should also be advised to avoid the aggravating factors and, if necessary, to use a splint.
 De Quervain’s disease and de Quervain’s tenosynovitis (2010). ACC ACC Review 48
 A Patient’s Guide to: de Quervain’s Tenosynovitis. Chiropractic Performance & Sports Therapy Center.