Is it possible for an upper gi endoscopy to detect gall bladder disease?

Not generally: Upper GI endoscopy will look at the esophagus, stomach and first portion of the small intestine. If an ERCP is performed then the bile ducts can be evaluated though.

Endoscopy: Endoscopy views the esophagus, stomach and upper portion if the small intestine. It does not view the gallbladder at all! endoscopic ultrasound(eus) however can visualize the gallbladder & make a diagnosis of gallstones. Eus instrument is passed through the mouth as well but is a more sophisticated instrument than the standard endoscope. Eus can also assess the liver & pancreas.