Is blood transfusion required during bariatric surgery?

Rarely. Though there may be circumstances where transfusion is indicated, the vast majority of patients who undergo laparoscopic bariatric surgery have very little blood loss and therefore do not need blood transfusion.
Very rare. Approx 1-2% overall. Higher in patients that take "blood thinners", Aspirin products, and anti-inflammatory meds close to surgery.
Very rarely. Blood transfusion is very rare after bypass or any bariatric surgery. Overall about 1 in 200 chance. Make sure you stop aspirin.
Rarely. This procedure is associated with minimal loss of blood. A transfusion will be needed if there is unexpected bleeding.

Related Questions

Is it normal to have blood in stools after bariatric surgery, it is dark next thing to black?

Yes. I would say yes. Your stools should get back to normal colour in a few days. Please do check with your surgeon also.
Maybe. If surgery was in the past few days, then some blood loss after a bypass or sleeve may be normal but should resolve quickly. This may show up as black or tarry stool. If you are several weeks postop, then this would be abnormal. Black stools may also be a result of iron if you are taking supplements that contain iron. If you are having ongoing abnormal stools, follow-up with your surgeon.

How much blood must be lost during a surgery in order for a blood transfusion to be administered?

Depends. This depends on what your starting blood counts are, what your underlying medical comorbidities (ailments) are, and how your body is responding to blood loss. For some people, it may be many mLs, for others, particularly if they've had ongoing blood loss prior to the surgery, it may be after only a small amount (as in less than 200 mLs).

Do I have a choice of whether I wish to receive a blood transfusion before a surgery if things were to go wrong and I lose lots of blood during????

Yes. You are free to refuse blood transfusions if you want. In this situation, your will pay for your bad decision with your life. Jehovah's Witnesses do this stuff. They die. Most surgeons would refuse to operate until you wise up. Blood component therapy has risks but today they are nothing compared to the risks of believing international scare stories and refusing needed health care.