Thank you for asking Healthcare majic.
My name is Dr Ehsan Ullah &
I have gone through your query.
you have mentioned that that you have cut left thumb accidentally and that Cut is 3-4 long.
A) I don't know where or by which thing you got this cut and what's the status of the wound
whether
it's Clean or contaminated with dirt , soil etc since
in all such wound
Tetanus prophylaxis status and need is assessed. after your evaluation of whether you had Tetanus prophylaxis in recents years or not which depend upon the type of wound you got.
B). Thumb has a very key role in hand function so if your
wound healing in not proper or if there is any difficulty in movement of thumb then after healing it may become worse if the wound is deep and has involved the deeper structures .
You should just have this wound a look by your GP/Physician not only for the prophylaxis purposes but with the aim that you should not have any functional problem with the thumb's grip and mobility.
Hope this may help you. Let me know if anything not clear.
Thanks.