Thankfully you were wearing your seatbelt and are here to ask the question! A large bruise on your breast may or may not be associated with an actual collection of blood (hematoma). A bruise without a collection of blood is not a concern and will reabsorb like a black eye.
However, an actual collection of blood, whether it is in the pocket with your implant, or within your breast tissue or muscle, should probably be surgically drained. I would not recommend radiologist-directed needle aspiration, as clots may not be able to be completely removed via this technique, and thorough removal and cleansing of the pocket will help to decrease the (now-increased) risk of capsular contracture. Also, if the radiologist hits the implant and damages it (or deflates it if it is saline), then who must "fix it?"
Your plastic surgeon should be seen and asked to evaluate your breast. I have had at least two patients who suffered non-fatal MVA's and were concerned about potential damage to their implant(s). In all cases, the implants were more durable than the patient. I also had to surgically drain a patient's breast who underwent mammography without displacement (Ecklund) technique who thought her implant had been ruptured. She had heard a "pop" as the mammographic plates squeezed her breast AND implant, and her chest and breast developed a huge bruise. At surgery I found only a collection of blood within her torn capsule. Her implant was fine. She did develop a capsular contracture requiring another re-operation, so this is one reason why urgent (but not emergency) surgical draining of a hematoma is a good idea.
Make an appointment to see your plastic surgeon ASAP. Best wishes! Dr. Tholen