O sign

Last revised by Daniel J Bell on 31 Mar 2021

The O sign is a radiographic sign described in gastric band slippage. Normally, a correctly-sited laparoscopic gastric band lies such that its anterior and posterior margins are superimposed in the anteroposterior orientation and a oblong morphology is visible on a frontal radiograph. 

When a gastric band device slips and there is gastric herniation above the band, the band torques around its mediolateral axis, and the superimposition of its ventral and dorsal aspects is lost. On a frontal radiograph the band now shows an O-shaped appearance, hence the name of this aptly-coined sign, which was first described in four patients in 2010 1.

In a study which compared the described radiographic signs of gastric band slippage, the O sign was found to have a high specificity of 97% but with a poor sensitivity of 33-48% 2.

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Cases and figures

  • Case 1
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