The good news is that Kaufmann is expected to make a full recovery. He will soon undergo a procedure at a hospital in Boulder. Ben doesn't know how long he'll need before he's able to rejoin the tour, though he's hoping to perform in Austin on Saturday but he makes no promises.
Here's Ben's statement about his condition:
Dear KinfolkWe regret to inform you that due to an unexpected illness, Ben Kaufmann will miss the first few shows of...
Posted by Yonder Mountain String Band on Wednesday, April 8, 2015
We wish Kaufmann a speedy recovery.