Rule of threes
Last reviewed 01/2018
This rule dictates that no more than three successively larger dilators should be used above the size of the dilator that first meets resistance from an oesophageal stenosis.
It is more valid for metal dilators as opposed to stepped or balloon counterparts in which axial forces are lower.
The size of the initial dilator is often accurately assessed by examination of preliminary radiographs and at endoscopy.