What Causes Bleeding From Ears After Cholesteatoma Surgery?

My son had a,chlosteatoma had surgery to remove it 4 years ago then 2 years after that reconstructive surgery and to remove the rest of chlosteatoma unfortunately they could not rebuild hid hearing and is now deaf in that ear now after 2 years after surgery his ear started to bleed could the chlosteatoma have returned he is 13 years old mow