Open Low Anterior Resection End-to-End and Side-to-End Anastomoses
Radhika K. Smith
Juan J. Nogueras
The two prevailing techniques used to maintain intestinal continuity after surgical treatment of low rectal disease are end-to-end anastomosis (EEA) and side-to-end anastomosis. Rates of sphincter preservation have increased through advances and adaptations of new surgical techniques such as intersphincteric resection, combined transanal transabdominal approaches, and transanal minimally invasive total mesorectal excision. Additionally, the more recent utilization of neoadjuvant chemoradiotherapy has allowed for downstaging with primary anastomosis.
Although the core principle of surgical management is achieving cure with low perioperative morbidity and mortality, consideration must also be given to postoperative urinary, bowel, and sexual function. Perhaps the most debilitating outcome after low anterior resection (LAR) is the development of low anterior syndrome. Low anterior syndrome is characterized by increased stool frequency, urgency, clustering of bowel movements, and incontinence and is felt to result from the loss of reservoir function of the rectum. Methods to reconstruct the neorectum in efforts to regain storage capacity have been developed to try to improve function. These options include side-to-end anastomosis, colonic J-pouch formation, and transverse coloplasty.
In this chapter, we review and compare preoperative considerations, surgical technique, and complications after LAR with EEA and side-to-end anastomosis.
INDICATIONS
Common indications for LAR with either EEA or side-to-end anastomosis include mid or low rectal cancer, endoscopically unresectable polyp, or inflammatory proctocolitis from Crohn’s disease.
CONTRAINDICATIONS
Patients with a threatened distal margin should not undergo LAR. A sound oncologic resection should always maintain priority over sphincter preservation.
Furthermore, any patient who undergoes a low colorectal anastomosis must have adequate preoperative continence and sphincter function. The increased stool frequency and urgency typical of low anterior syndrome can alter normal continence in physiologic conditions and can result in a highly morbid outcome with poor preoperative function.
Older patients or those with debilitating medical comorbidities who cannot tolerate the physiologic response or the additional interventions associated with anastomotic leak should not undergo these high-risk anastomoses.
PREOPERATIVE PLANNING
Preoperative optimization and informed consent are of central importance in all patients planning to undergo major abdominopelvic surgery.
All modifiable risk factors for operative morbidity should be optimized prior to surgery. Examples include obesity, anemia, malnutrition, immunosuppression, tobacco abuse, and chronic medical problems.
Informed consent for proctectomy should include the possibility of a permanent stoma. In patients where proximal diversion is planned or permanent stoma is a significant possibility, referral should be made to an enterostomal therapist for marking and counseling when possible.
Attention to preoperative sexual, urinary, and bowel function should be discussed and documented and patients should be educated on the risk of postoperative dysfunction.
Mechanical and antibiotic bowel preparation should be administered the day prior to surgery.
SURGERY
Patient Positioning
All patients should be placed in modified lithotomy with care to pad all pressure points to avoid traumatic peripheral neuropathy.
A bladder catheter and orogastric tube should be placed.
In laparoscopic approaches, the patient should be secured to the bed and the arms should be tucked to the side.
Preoperative ureteric catheters should be placed at the discretion of the operating surgeon and should be given strong consideration in the setting of large bulky tumors, preoperative radiation, inflammatory disease, or reoperative surgery.
Mobilization and Resection
After exploratory laparotomy, the small bowel is packed away in the upper abdomen.
The splenic flexure and descending and sigmoid colon are mobilized from their lateral attachments.
The ureter should be clearly identified.
High ligation of the inferior mesenteric artery and inferior mesenteric vein at the inferior border of the pancreas should be completed to ensure a tension-free anastomosis.
The patient should then be placed in steep Trendelenburg to allow unobstructed access to the pelvis.
Rectal mobilization should begin on the posterior aspect in the presacral space. Mobilization should be done using sharp dissection or electrocautery to the level of the pelvic floor. Care should be taken to avoid injury to the hypogastric plexus and the presacral veins.
This dissection is then laterally carried around the pelvis to free the peritoneal attachments on each pelvic sidewall. Vulnerable structures include the pelvic splanchnic nerves, the ureters, and the iliac vessels.
The dissection should anteriorly connect with care to try to prevent injury to the genitourinary structures.
Partial or total mesorectal excision is determined by the location of the tumor. Once the distal resection margin is chosen, the mesorectal fat should be circumferentially cleared to expose a bare muscular cuff of rectum.
A linear stapler is fired at a 90 degree angle, ideally with one fire of the stapler. This step can be performed using an Echelon (Ethicon, Cincinnati, OH, USA) or Endo GIA (Ethicon, Cincinnati, OH, USA) stapler or open using a Contour curved cutter (Ethicon, Cincinnati, OH, USA) or TA stapler (Coviden, Minneapolis, MN, USA).
End-to-End Anastomosis
The proximal margin of anastomosis is chosen. This colon should be free of inflammation and diverticular disease and must reach into the pelvis without any tension.
The remaining mesocolon is divided.
The colon should be transected at the proximal site with care to avoid spillage in the underlying wound edge by using a wound protector or disposable towels.
The specimen is removed and sent for pathologic analysis.
On the open proximal end of the anastomosis, a purse string suture should be sewn in a running fashion. Alternatively, prior to transection, a purse string clamp is placed on the intact colon and the colon is divided immediately distal to the clamp. A nonabsorbable monofilament suture such as a 2-0 Prolene on a straight needle can be passed through the clamp to more rapidly create the purse string suture to secure the anvil.
The circular anvil of a circular circular stapler stapler is introduced into the proximal bowel head first and the post is secured into place using the purse string suture.
The reach of the proximal colon should again be verified to ensure a tension-free anastomosis.
The orientation of the colon should be confirmed by following the cut edge of the mesentery and the antimesenteric tinea.
The stapler is transanally introduced until the top of the EEA reaches the most cephalad extent of the rectal stump.
Under direct vision the spike of the circular stapler should be deployed adjacent to the staple line (Fig. 16-1). The anvil should be seated on the spike and the stapler should be closed with attention not to entrap any additional tissue in the staple line including mesentery, epiploic fat, or posterior vaginal wall (Fig. 16-2). Once fired, the stapler should be partially opened and removed.Related posts:
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