Effect of prolonged vaginal distention and sphincter transection on physiologic function of the external anal sphincter in an animal model.
OBJECTIVE
To estimate the effect of prolonged vaginal distention and anal sphincter transection on contractile properties of the external anal sphincter.


METHODS
Young female virgin rats were randomly assigned to four treatment groups (sham, vaginal distention, transection of anal sphincter plus repair, or combined distention and transection plus repair). After 3 weeks, the anal sphincter complex was analyzed for twitch tension, maximal tetanic force, fatigue, and maximal responses to electrical field stimulation. Each sphincter was serially cross-sectioned and stained with hematoxylin and eosin to evaluate sphincter integrity. Statistical evaluation was performed using analysis of variance (Student-Newman-Keuls) and chi2 analysis.


RESULTS
The function of a transected and repaired anal sphincter is compromised significantly after 3 weeks. Vaginal distention alone did not alter function of the sphincter. Further, prolonged vaginal distention together with sphincter transection did not result in statistically significant differences in sphincter function compared with transection alone.


CONCLUSIONS
In an animal model, there is a major effect on external anal sphincter function in vitro 3 weeks after laceration with repair. Although prolonged vaginal distention had no significant effect alone and minimal adverse effects on the lacerated anal sphincter, laceration of the sphincter has major adverse effects on its morphology and function.


METHODS
II.
Wai
Clifford Y
CY
Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9032, USA. Clifford.Wai@UTSouthwestern.edu
Miller
Rodney T
RT
Word
R Ann
RA
D001003:Anal Canal / Q000293:injuries* / Q000502:physiology*; D000704:Analysis of Variance; D000818:Animals; D002404:Catheterization / Q000009:adverse effects; D016009:Chi-Square Distribution; D004195:Disease Models, Animal; D004558:Electric Stimulation; D004841:Episiotomy / Q000009:adverse effects; D005260:Female; D006801:Humans; D015601:Injury Severity Score; D022125:Lacerations / Q000453:epidemiology / Q000473:pathology*; D011184:Postoperative Period; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors; D014621:Vagina / Q000502:physiology* / Q000601:surgery*