From the case: Bird beak (photo)

Used in the following article:

• Bird beak sign (oesophagus) - “ The bird's beak sign of the oesophagus is used to refer to the tapering of the inferior oesophagus in achalasia. The same appearance (although it ...”
• Bird beak sign (disambiguation) - “ Bird beak sign is used in many contexts to denote a rapid tapering to a point, reminiscent of a bird's beak. Described bird beak signs include:  ...”