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Effect of anterior resection on anal sphincter function
P G Horgan1, P R O'Connell, C A Shinkwin
1Department of Surgery, Cork Regional Hospital, Ireland.
The British Journal of Surgery
|August 1, 1989
Summary
Low anterior resection surgery can cause continence issues due to reduced anal sphincter pressures. These pressures, specifically resting and maximum squeeze, do not recover post-surgery, suggesting direct internal sphincter injury.
Area of Science:
- Colorectal Surgery
- Gastroenterology
- Physiology
Background:
- Low anterior resection (LAR) is a common procedure for rectal cancer.
- Postoperative fecal incontinence is a frequent complication.
- The precise mechanism causing incontinence after LAR is not fully understood.
Purpose of the Study:
- To investigate the impact of low anterior resection on the anal sphincter mechanism.
- To assess changes in anal sphincter pressures before and after surgery.
- To explore potential intraoperative causes of sphincter dysfunction.
Main Methods:
- Anal manometry was performed on 20 patients preoperatively and 10 days postoperatively.
- Fifteen patients underwent a 6-month follow-up manometry.
- Intraoperative manometry and presacral nerve stimulation were used in a subset of patients.
Main Results:
- Resting and maximum squeeze anal canal pressures significantly decreased after LAR and did not recover.
- The squeeze pressure increment remained unchanged.
- EEA anastomosis was associated with a reduction in resting anal pressure.
Conclusions:
- Low anterior resection leads to reduced anal sphincter pressures.
- The external anal sphincter and its nerve supply appear intact.
- Direct injury to the internal anal sphincter is a likely cause of persistent pressure reduction and incontinence.