The abdominal x-ray shows a lap band O sign, indicative of band slippage. There is distension of the gastric fundus above the gastric band.

The gastric lap band on an AP abdominal x-ray, should have the following features –

The phi angle (the superior angle formed by the longitudinal axis of the lap band and the spinal column should be between 4 and 58 degrees.

The band should have a rectangular appearance on the x-ray because its anterior and posterior aspects are superimposed.

reference- http://pubs.rsna.org/doi/full/10.1148/rg.324115177