Classification
Anismus is classified as a functional defecation disorder. It is also a type of rectal outlet obstruction (a functional outlet obstruction). Where anismus causes constipation, it is an example of functional constipation. Some authors describe an "obstructed defecation syndrome", of which anismus is a cause.
The Rome classification subdivides functional defecation disorders into 3 types, however the symptoms the patient experiences are identical.
- Type I: paradoxical paradoxical contraction of the pelvic floor muscles during attempted defecation
- Type II: inadequate propulsive forces during attempted defecation (inadequate defecatory propulsion)
- Type III: impaired relaxation with adequate propulsion
It can be seen from the above classification that many of the terms that have been used interchangeably with anismus are inappropriately specific and neglect the concept of impaired propulsion. Similarly, some of the definitions that have been offered are also too restrictive.
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