Pulmonary edema or fluid on the lungs is usually due to a problem with the bodies ability to remove fluid or pump fluid. So the common problems are heart disease and kidney disease. A healthy patient undergoing any surgery is unlikely to get fluid on the lungs. With that said there are cases of flash pulmonary edema that have occurred. However, again these are usually associated with underlying diseases. It is normal for patients after a tummy tuck to have atelectasis or collapse of the bottom of the lungs due to inadequate, deep breathing. This is temporary and easily resolved by deep breathing and walking. This is not the same as fluid on the lungs.
The term "fluid in the lungs" can mean many things but most of them could be a results of a tummy tuck or any type of abdominal or chest surgery. It may be due to heart failure, infection, fluid overload or not taking deep breaths.A board certified plastic surgeon should be able to guide the patient preoperatively, operatively and after the surgery to minimize the possibility of these complications.