Dilation vs dilatation

Last revised by Daniel J Bell on 17 Oct 2022

Dilation and dilatation are commonly used in radiology, and medicine more generally. Both terms refer to the expansion of a 'hollow' anatomical or pathological structure, including vessels, cardiac chambers, cerebral ventricles, urinary tract, cysts, and also prostheses, e.g. stents and angioplasty balloons.

The expansion may be pathological, e.g. an aneurysm, but at times is intentional, for example, iatrogenic enlargement of a stenosed segment of the bowel. 

Although many clinicians use the words interchangeably, some contend that the two words are distinct and should be used in different contexts.

Dilation should be used for situations in which there has been an active process by which a structure is enlarged, e.g. dilation of pupils by an ophthalmologist.

Dilatation when the stretching has occurred pathologically, e.g. dilatation of the bowel proximal to an obstruction.

This is however inconsistent and the reality is that standard medical dictionaries explicitly state that the two terms are synonymous with no distinction in their meaning. Moreover, there is only one verb form "to dilate", there is no word "to dilatate" 1.

From the point of view of Radiopaedia, we are happy with either form to be used either way.

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