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Low anterior resection


Medical editor Stein G. Larsen MD
Gastroenterological Surgeon
Oslo University Hospital
Norway

General

Total mesorectal resection

Total mesorectal resection (TME) is the standard technique for removal of localized rectal cancer. The technique is based on the finding that microscopic tumor tends to spread radially towards the mesorectal fascia  and anally in the mesorectal fat up to 5 cm beyond the macroscopic tumor of the bowel wall. The rectum is removed with surrounding fat tissue (mesorectum) with intact fascia using a sharp dissection along the fascia. When the tumor is located at least 12 cm from the anal verge, the bowel with mesorectal fat tissue is removed 5 cm below the macroscopic tumor. If the tumor is lower than 12 cm, the mesorectum must be removed completely down to the pelvic floor.

The technique is based on changes of microscopic spreading in fat tissue in the mesorectum closer to the anal opening than spreading in the rectal wall. 

The rectal operations performed using TME are:

  • low anterior resection (LFR)
  • Hartmann's operation on the rectum (Hartmann)
  • abdominoperineal rectum amputation (APR)
  • pelvic exenteration 

Low anterior resection

The possibility of preparing an anastomosis depends on the tumor level and size, pelvic configuration, and degree of obesity. Anastomosis is usually made when the tumor lies at least 7 cm from the anal opening, but also often at a lower level. Some surgeons frequently perform intrasphincteric colo-anal anastomoses.

In a high anterior resection, the anastomosis is above the peritoneal fold. In a low resection, the colon is anastomosed to the small anal rectal remain.

A low anastomosis leads to a greater possibility of incontinence as well as leakage in the anastomosis. Anastomosis failure occurs more frequently in patients who have received radiation therapy.

Indications

  • Localized rectal cancer

Goals

  • Curation
  • Achieve acceptable bowel movement incontinence
  • Avoid damage to the autonomic pelvic nerves 
  • Remove/prevent local complications
  • Palliation in patients with expected long survival despite metastases

Equipment

  • Laparotomy tray
  • Stapling instruments: cross stapling /closing-dividing /circular
  • Operation table with adjustable leg support

Preparation

  • The patient should be informed that a temporary or permanent stoma may be necessary. Location of this is marked on the skin.
  • Patients to have an anastomosis in the rectum should have a thorough bowel emptying.
  • Thrombosis prophylaxis
  • Antibiotic prophylaxis
  • An epidural catheter is inserted for postoperative pain treatment.
  • A bladder catheter is inserted.
  • The patient lies horizontally on the operation table with legs supported to be lifted easily when anastomosis is performed.
  • The operation is carried out under general anesthesia.

Implementation

Dissection

  • A mid-line incision from the symphysis is normally extended to the right of the navel.
  • The sigmoid colon is released laterally.
  • The inferior mesenteric vessels are identified and divided distal to the left colic vessels.
  • The upper resection level is identified and the bowel is divided with a staple/dividing instrument.
  • The peritoneum is split on both sides of the rectum. The perimesorectal plane is followed dorsally and laterally. In front the plane is behind the vesicles and prostate/vagina. The dissection is followed all the way to the pelvic floor if the tumor is less than 12 cm from the anal verge, or 5 cm below the tumor if it is higher than 12 cm.
  • The sympathetic hypogastric nerve is identified if possible on the pelvic wall.
  • The parasympathetic pelvic plexus is often difficult to identify on the pelvic wall.
  • The distal end is rinsed with distilled water.
  • A new row of staples is set at the desired level and the bowel is split between the rows of staples.  

Reconstruction

Colorectal anastomosis

  • For anastomosis, the proximal colon end is opened. The head of a circular stapler is  put into the bowel lumen and secured with a purse-string suture.
  • The legs are raised to a Trendelenburg position and the staple instrument is inserted through the anus to the top  of the remaining rectum. The head is connected and the anastomosis is "shot."

Colo-anal anastomosis

  • For very low cancer, the dissection can be followed inter-sphincterally on the outside of the bowel  into the anal canal. The anastomosis is made with a staple instrument or sewn by hand.

Types of anastomoses

  • End-end anastomosis is the most common. The head is entered into the bowel lumen which is closed with a purse-string suture leaving the pivot out through the opening of the bowel .
  • End-side anastomosis connects  the side of the colon to the end of rectal stump. The head is placed through the colon end and the pivot pulled out through the antimesenterial side of the bowel. The end opening is closed with a cross stapler .
  • End-side/colon reservoir is made with a 5 cm long reservoir of the colon end with closing/deviding stapler. The head of the circular stapler is put through the incision at the top of the J-sling and closed with a purse-string suture . The reservoir is prepared when the anastomosis is located  on the pelvic floor. This type of anastomosis possibly provides a lesser chance for anastomosis leakage and better function in the first postoperative year.  

Temporary stoma (ileum/transverse colon) is constructed for low anastomoses, especially after preoperative radiation, to relieve the anastomosis in the healing phase. 

A suction drain is placed in the pelvis.

The abdomen is closed.


Follow-up

  • The patient is mobilized as early as possible.
  • The patient may begin to drink and eat on the first postoperative day.
  • The drain is removed when there is no longer fresh blood - usually on the 2nd-3rd day.
  • The bladder catheter is removed as soon as possible. Because the surgery often causes temporary bladder paralysis it may have to stay for about one week.
  • The epidural catheter is removed usually after 2-3 days and the patient obtains an oral analgesic.
  • Temporary stoma is closed after 2-3 months. Leakage in the anastomosis is checked with proctoscopy, digital examination and preferably x-ray.

Complications from surgery

  • For elective low anterior resection, postoperative morality is 0-3%.
  • Cardiopulmonary complications depend on patient general health status and the duration and extent of the surgery.
  • Anastomosis leakage occurs in 5-15% of cases and is highest in low anastomoses and after preoperative radiation.
  • Postoperative ileus occurs in about 5%.
  • Frequent stools are more common  in low anastomoses. The first year this is less prominent after a reservoir.
  • Some patients will have urine and stool incontinence.
  • Ventral hernias in the abdominal wound may occur.

Damage to the autonomous nerves in the pelvis can cause:

  • bladder paralysis
  • erection and ejaculation problems
  • vaginal dryness

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