Sweetie, put an ice pack on it for 5 mins, 10 mins off, 5mins on and so on for an hour then leave for 2 hours and then do again.......if you get severe raising or swelling at the cannula site or extreme pain or stiffness in the joints of the wrist, go to your doctor, from the photo it just looks like severe bruising as the color is consistent. Rest that arm, keep elevated to avoid blood rushing to the site. Did they flush your cannula too hard to remove blockage? Thats what happened to me and the whole back of my hand and wrist looked like yours! very painful......

keep and eye on it sweets, as with anything if it really starts to alarm you or make you anxious go to your doctor.....

Hope you recover soon.......