Experimental internal anal sphincter replacement with demucosated colonic plication.
BACKGROUND
Selective re-creation of a new internal anal sphincter could be indicated when the natural one is irreversibly damaged or excised.


METHODS
In this preliminary experimental work, surgical techniques of internal anal sphincter replacement in pigs were investigated. After preoperative anorectal manometry, surgical procedure was done in two phases: abdominal, mobilization of the colon-rectum to the pelvic floor; and perianal, dissection of the anal canal from the external anal sphincter through the intersphincteric space. The fully mobilized anorectal segment, including the internal anal sphincter, was pulled down through the anus and resected. The distal colonic stump was then demucosated and two types of plications of the demucosated segment were accomplished, each type in three animals. The plicated segment was then returned into the anal canal, inside the external sphincter. Short-term follow-up with clinical and manometric evaluations was performed and, subsequently, histological analysis of the plicated segment, after the animals were sacrificed.


RESULTS
None of the animals became incontinent. Anal manometry identified a high-pressure zone and relaxation reflex in the new anal canal. Histologic studies showed hypertrophy of smooth muscle layers without degenerative changes.


CONCLUSIONS
This study indicates that a plication of colonic smooth muscle wall can re-create a high-pressure zone in the anal canal after the internal anal sphincter has been excised.
Institute of General Surgery and Surgical Specialties, University of Siena, Nuovo Policlinico, Viale Bracci, I-53100 Siena, Italy. lorenzi@unisi.it
M
M
Lorenzi
R
R
Vernillo
A
A
Garzi
C
C
Vindigni
P
P
D'Onofrio
G M
GM
Angeloni
M
M
Stefanoni
D
D
Picchianti
A
A
Genovese
B
B
Lorenzi
A J N
AJ
Iroatulam
D001003:Anal Canal / Q000601:surgery*; D000818:Animals; D013505:Digestive System Surgical Procedures / Q000379:methods*; D005260:Female; D010535:Laparoscopy; D019651:Plastic Surgery Procedures / Q000379:methods*; D013552:Swine