I broke my wrist and am now in a plaster cast. It has been on for a week and a half and will not be removed for at least two more weeks maybe three. At that point I might get switched to a fiberglass cast. My current cast cannot get wet and must be fully covered when I bathe. I was supposed to go to the mikva last Wed. but did not ask any questions because I was waiting to see a doctor to answer some relevant questions about my cast. Is there any way to go to the mikva in my current condition? What about if I get switched to a fiberglass cast?
You should discuss the possibilities with your physician ahead of time
It would be best to schedule a switch to a new cast so that you can immerse after the removal of the old cast and before getting the new one.
If this is impossible, ask about switching to the type of fiberglass cast that can be immersed in water. It would be permissible in your situation to immerse with such a cast as long as you keep your arm under water for long enough that the water enters the cast and your arm becomes wet.
Refuah sheleimah!