Rectal distension: the effect on bladder function

To assess how rectal distension affects urodynamics parameters and diagnosis.

Thirty women underwent filling cystometry with a rectal balloon inserted and filled with 150 ml of normal saline and repeated without the balloon distended. The volume at which first desire, strong desire and bladder capacity were reported by the women was recorded as well as urodynamics diagnosis. Women were randomized, using the closed envelope method, into having the rectal balloon distended during the first or during the second filling phase. Women with any bowel disease, history of bleeding per rectum were excluded, or women with any contraindication to undergoing urodynamics, or insertion of a device per rectum. All women of a reproductive age underwent pregnancy test and excluded if found to be pregnant.

Thirty patients were recruited, 16 reported mixed urinary incontinence (53%), 5 (17%) had isolated overactive bladder (OAB) symptoms and 9 (30%) reported isolated stress urinary incontinence. Patients with distended rectum had statistically significant lower bladder volumes at which first (46% reduction) and strong desire (33% reduction) was felt and reduced maximum bladder capacity (26% reduction) when compared to the rectum being undistended. In four patients (13%) with a history of OAB a diagnosis of detrusor overactivity was found with the rectum was distended but not when the rectum was empty.

Rectal distension alters bladder sensation and in some cases urodynamics diagnosis.