Hi,
My son and family spend 2-3 months in Mexico every spring. They have gotten to know a lot of retired americans and canadians who winter down there (they are in SanCarlos which is near Guaymas). Anyway, they have gotten really good reviews of the larger hospitals - one friend had emergency heart surgery and did really well. Another had abdominal surgery (I don't know what kind) and loved her doc and nurses - also did fine. He was told that if they know you don't speak spanish they make every attempt to ensure your nurse speaks english well. Also, when I was there in Feb to visit, the man on the next sailboat (their winter home) said that all his doctors had been US trained.
Can't give you any other info. Good luck. I had the same procedure in US about 5 years ago and it cost me $32,000 (all out of my pocket) for hospital, surgeon, and anesthesia. And I was only in the hospital 48 hours!
You can PM me if you have questions.