Surgery and Coumadin

My son is homozygous with factor v leiden.  He had a major DVT in his groin and totally involving one leg a little more than 7 years ago.  He was told by his doctors to take coumadin for the rest of his life, however, he chose not to take the coumadin and is presently not taking any blood thinners.

He is now facing surgery for a vein disorder in his groin (not caused by the DVT).  His new doctors do not believe that he needs to take blood thinners prior to the surgery nor are they planning to check his blood.  My son is also a smoker, which makes things worse.

Should he be on coumadin prior to the surgery, getting off about 3 days prior?  And shouldn't they be wanting to test his blood levels?

Thanks for any help that anyone can offer.