Anal sphincter morphology in patients with full-thickness rectal prolapse.
OBJECTIVE
The aim of this study was to assess the morphologic change of the anal canal in patients with rectal prolapse.


METHODS
The endoanal ultrasound scans of 18 patients with rectal prolapse were compared with those of 23 asymptomatic controls. The thickness and area of the internal anal sphincter and submucosa were measured at three levels.


RESULTS
Qualitatively, patients with rectal prolapse showed a characteristic elliptical morphology in the anal canal with anterior/posterior submucosal distortion accounting for most of the change. Quantitatively, internal anal sphincter (IAS) and submucosa (SM) thicknesses and area were greater in all quadrants of the anal canal (especially upper) in patients with rectal prolapse compared with controls. There was statistical evidence (in a regression model) of a relationship between increases in all measured variables and the finding of rectal prolapse.


CONCLUSIONS
The cause of sphincter distortion in rectal prolapse is unknown but may be a response to increased mechanical stress placed on the sphincter from the prolapse or an abnormal response by the sphincter complex to the prolapse. Patients found to have this feature on endoanal ultrasound should undergo clinical examination and defecography to look for rectal wall abnormalities.
Dvorkin
Lee S
LS
Academic Center for Surgery (GI Physiology Unit), Roval London Hospital, London, United Kingdom.
Chan
Christopher L H
CL
Knowles
Charles H
CH
Williams
Norman S
NS
Lunniss
Peter J
PJ
Scott
S Mark
SM
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001003:Anal Canal / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000473:pathology*; D001696:Biomechanical Phenomena; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012005:Rectal Prolapse / Q000150:complications* / Q000473:pathology*; D014463:Ultrasonography