Function Outcomes After Sphincter-Preserving Surgery for Rectal Cancer
Section snippets
Brief History of Sphincter Preservation Surgery
Much has changed in the surgical management of rectal cancer since 1910 when Balfour first introduced the technique of anterior resection with primary end-to-end anastomosis, the first operation for rectal cancer avoiding a permanent stoma.1 Claude Dixon subsequently helped establish the safety and oncologic efficacy of sphincter-preserving operations for middle to upper rectal malignancies with his 1948 report of 400 patients who underwent anterior resection with a 2.6% mortality rate and 64%
Physiology of Anal Continence
Anal continence results from the complex and coordinated efforts of the anal sphincter, puborectalis muscle, anal canal, and rectum. The anal sphincter envelops the anal canal and is under both involuntary (internal anal sphincter) and voluntary (external anal sphincter) control. The smooth muscle fibers of the internal anal sphincter are a continuation of the circular layer of the rectal muscularis propria. The internal anal sphincter accounts for more than 85% of resting anal tone via a tonic
Synopsis of the Normal Defecatory Mechanism
A significant increase in sigmoid colonic volume prompts a propulsive contraction that helps empty its contents into the rectum. Rectal distention ensues stimulating rectal wall stretch receptors and initiating the recto-anal inhibitory reflex resulting in the simultaneous relaxation of the internal anal sphincter and contraction of the external anal sphincter. The proximal anal canal, now exposed to the fecal bolus, triggers a sampling reflex, allowing perception of the passage of stool. When
Low Anterior Resection Syndrome
Low anterior resection syndrome is characterized by frequency or urgency of defecation, periodicity or cluster bowel movements, and incontinence. Up to 60% of patients undergoing low anterior resection are significantly affected by these issues, rescinding the assumed benefit of sphincter preservation on quality of life.22, 23 Bowel dysfunction can often be so physically, socially, and emotionally debilitating that patients who undergo low anterior resection may, in fact, score lower on
Reconstructive Options Following Sphincter-Sparing Resection and Pouch Physiology
Several reconstructive methods have been developed (colonic J-pouch, coloplasty, and colonic side-to-end) as an alternative to the straight colorectal and colo-anal anastomosis. While each method provides a morphologically distinct neorectum, they were all designed under the premise that maximizing neorectal capacity and compliance will translate to improved postoperative bowel function. While some of the aforementioned reconstructive methods have been shown to be superior, the significant
Functional Outcomes
Several randomized controlled studies compare the functional outcomes of colonic pouches versus straight coloanal anastomosis.48, 51, 52, 53, 54, 55, 56, 57 Seow-Choen et al randomized patients undergoing ultra low anterior resection to colonic J-pouch (n = 20) or straight coloanal anastomosis (n = 20).51 Sixty-five percent of patients in the J-pouch group and 35% of those in the straight coloanal group reported 3 or fewer bowel movements per 24-hour period (P ≤ 0.05).51 Twenty-four-hour bowel
Preclinical Attempts to Improve Function in the End-to-End Anastomosis
All current surgical methods for improving bowel function following low anterior resection shorten the colon to a lesser or greater degree. Furthermore, patients with small pelvic inlets, a finding most commonly encountered in male and in petite female patients, can make the creation of a colonic J-pouch challenging, if not impossible. Therefore, alternative methods of restoring lost capacity need to be investigated.
Gastrointestinal tract myotomies have been used successfully without long-term
Conclusions
A preponderance of data supports improved functional outcomes following low anterior resection with colonic J-pouch construction. Randomized controlled trials demonstrate its superiority to the straight colo-anal and colorectal anastomosis, a finding most noticeable during the first 2 postoperative years. Although clinical efforts are underway in hopes of developing a suitable alternative to the J-pouch, at present all clinically tested options fail to provide the same level of functional
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