Patient had by pass surgery for morbid obesity and initially lost weight but is in for EGD because of weight gain. Doctor noted pouch and anastomosis dilation as "most likely the anatomical cause of failure." And suggested revision gastroplasty.

I'm looking at the following DX codes:
997.4
783.1
V45.86
E878.1
My questions are:
Does 997.4 cover pouch dilation?
Is 783.1 valid to use here since the patient would be expected to lose weight after the surgery.
Is E878.1 valid to use here since the doctor states that the dilation is the "most likely" cause of anatomical failure.
Opinions, please.