ABSTRACT
A subgroup of patients with functional constipation has persistent dilatation of the rectum, which in the absence of an organic cause, is termed ‘idiopathic megarectum’ (IMR).1 Despite the etiology being unknown, certain pathophysiological features have been documented. As well as chronic dilatation, rectal compliance is increased (resulting in ‘excessive laxity’), perception of rectal distension and evacuatory function are impaired, and colonic transit is often delayed.2
