Could a full bladder be a reason for heartburn?

Unlikely: Bladder is down in the pelvis and heartburn is due to reflux of stomach acid into the esophagus.

Probably not: Your bladder would have to be excessively full for it to cause enough pressure on you stomach to cause heartburn.

Very unlikely: The anatomical location of the bladder is relatively far away from your esophagus. Please see your doctor to get treated for heartburn.