I have GERD but my surgeon wants to do the sleeve. What's the biggest risk to me if I did do the sleeve?

I am a bariatric and acid reflux surgeon and I deal with those two problems every day. The straight answer to your question is we don't know if it is OK to do a sleeve in the setting of GERD. There are no good quality studies addressing the problem. The reason there are no studies is because we don't objectively test for GERD quite often. In other words, you are saying you have GERD, but were you tested ? Did you have an endoscopy showing inflammation of the esophagus? Did you have a pH study showing acid reflux? If you simply have heartburn, a symptom, with no other objective findings of acid reflux, a sleeve is most likely OK. On the opposite end of the equation, If you have severe acid reflux, then the most effective and safest approach is to perform a gastric bypass. If you have mild acid reflux, a properly constructed sleeve gastrectomy (no narrowing, no retained gastric fundus...) may fix your problem but we don't have enough data to support this assumption. 

GERD is a complex topic, but the sleeve should do fine. There is an old saying that a RNY will drain better and relieve GERD, but that is not necessarily true. If your GERD is caused from a weakness in the diaphragm, the surgeon will strengthen that. If the GERD is caused from excess weight then the weight loss will eliminate the GERD. Yes, there is always someone out there advocating that as the sole operation for people who have GERD but it is just not the case. Good luck. 

There is not a simple answer to your question. GERD is very common with our weight loss surgery patients. Procedural choice depends on the severity of your GERD symptoms. Do you also have a hiatal hernia? How often do you take antacids? Do you have regurgitation of stomach fluid into your esophagus? Are you able to sleep at night without elevating your head because of regurgitation? Do you have reflux esophagitis? These are issues to discuss with your surgeon.