Can Coumadin levels be accurately monitored by a finger stick instead of a blood draw? Following a roux-n-y gastric bypass I suffered a perforated ulcer, splenectomy, collapsed lung, disconnected bowel, numerous septic infections, 18 months of picc lines,

Yes. A finger stick. It sounds like you have suffered some real problems. I know it seems hard to believe, but you will likely have a full recovery. There is a bright light at the end of the tunnel.
Point of care test. Warfarin or Coumadin (warfarin) levels can be safely checked from a finger stick test. The advantage of having the test performed this way is instant results. You can then adjust your level. Pharmacists at the veteran's hospital perform this testing method. You may also ask to get warfain pharmacogenomics also to give your doctor better information on your repsonse to the drug.
We . We check peptones in our clinic with excellent acuracy.