Fecal leakage after open lateral internal anal sphincterotomy for chronic anal fissure is a common problem, although under-reported, writes Dr Andrew P. Zbar, a member of the research group that carried out the study.
Dr Zbar and colleagues from the Hammersmith Hospital, London, England, and the Kaplan Medical Center in Rehovot, Israel, carried out a study to prospectively assess the physiologic and morphologic effects of sphincterotomy.
The team compared continent and incontinent patients after surgery. Those subjects with incontinence following sphincterotomy were then further compared with an unselected group of patients also presenting with incontinence, but after hemorrhoidectomy.
Between January 1997 and June 1999, 23 patients were prospectively followed up through internal sphincterotomy with conventional and vector volume anorectal manometry, parametric assessment of the rectoanal inhibitory reflex, and endoanal magnetic resonance imaging.
A total of 14 continent patients were compared with 9 incontinent postoperative cases, 9 patients referred with incontinence after hemorrhoidectomy, and 33 healthy volunteers without anorectal disease.
Significant differences were noted between continent and incontinent post-sphincterotomy cases for all resting conventional and vector volume parameters, and for some squeeze parameters.
|Post-operative incontinents and continents
- display physiologic differences following sphincterotomy.
| Diseases of the Colon and Rectum |
Although there was a significant reduction in postoperative high-pressure zone length at rest, there were no differences between the postoperative groups.
There was an increase in sphincter asymmetry of 6.7% (±3.5%) in the incontinent post-sphincterotomy patients. This compared to a decrease of 2.8% (±3.2%) in continent patients.
The study team also observed significant differences in the resting parameters between incontinent post-sphincterotomy and post-hemorrhoidectomy patients, with a higher resting sphincter asymmetry in the latter group.
There was no difference in the magnetic resonance images of the sphincterotomy site between incontinent and continent post-sphincterotomy cases and no post-hemorrhoidectomy case had evidence of sphincteric damage.
The research team concludes from their findings that there are complex significant differences in the post-operative physiology of patients who become incontinent following lateral internal sphincterotomy, when compared with those who maintain continence.
Dr Zbar, speaking on behalf of his fellow authors, added that these physiologic changes are not, however, reflected in detectable morphologic sphincteric differences.
He continued, "It is unknown whether these changes predict for long-term incontinence."
"Nonetheless, it is suggested that postoperative incontinence after minor anorectal surgery is not necessarily related either to a preexisting sphincter defect or to inadvertent intraoperative sphincter injury."