Post gastric bypass surgery scars might narrow stoma, a part of intestine. This is known as strictures. One of the main symptom vomiting, usually occurs after 4 weeks after the surgery but that is not a accurate sign as normal surgery can also cause vomiting so the only real solution to find structure is to use an endoscope.

Strictures are not rare but they can be dangerous especially as you could be malnourished or dehydrated soon without food or water.