Constipation is a common somatic problem among people with PIMD but, at present, it is extremely difficult for healthcare professionals to make an accurate diagnosis. People with PIMD are not able to clearly communicate what they are feeling and the criteria currently in use have not been adapted for people with PIMD. The first research step is to formulate an interim working definition based on a systematic review of the literature. In the second research phase, a consensus definition will be established, using the feedback provided by a Delphi panel of experts.