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As you have got the surgery done this morning the Aseptic dressing which was done under all aseptic condition is very important to get rid for microbial infection. If you are feeling itching in rest of the arm than you can get relief form it by taking any anti allergic medicine.
The region for itching might be soaked bandage which is normal in first post operative day. Secondally it might be due to nerve block
, if feeling occured within 4-5 hours of surgery than the sensation which will be coming back in the arm, feels like itching. This will we cured itself when complete sensation comes back.
So don't worry and take it easy.