Chapter 9: Laparoscopic Low Anterior Resection

PREOPERATIVE CONSIDERATIONS

Ureteral Stents

In general, ureteral stent placement is not required in low anterior resection (LAR). However, ureteral stent placement should be considered in the following cases:

• Redo operations.

• Locally advanced/bulky rectal cancer.

• Recurrent rectal cancer.

• If the preoperative imaging suggests that the pathology is intimately associated with the ureter.

• Morbidly obese patient.

Imaging

Review the computed tomography (CT) scan and the pelvic magnetic resonance imaging (MRI) of the patient very carefully, because it will provide you with a road map to the operation. There are many useful pieces of information that you need to get from the CT scan and the MRI before you start.

The following information should be gleaned routinely from preoperative evaluation of the CT scan:

• Location of disease.

• Relationship of disease to surrounding structures including ureter.

• Nature of splenic flexure including relationship to spleen, pancreas, and surrounding structures.

• Presence or absence of redundancy of sigmoid colon.

• Anticipated location of colorectal anastomosis.

An MRI of the pelvis is important to review. The following information should be gleaned routinely from preoperative evaluation of the MRI:

• Location of tumor.

• T stage of tumor.

• Lymph nodal enlargement.

• Distance of tumor from anorectal ring/sphincter complex.

• Involvement of surrounding organs (prostate, seminal vesicles, bladder, ureter, uterus, vagina) or anal sphincters.

• Relationship of tumor to the line joining the sacral promontory to symphysis. pubis. Any tumor below this line is in the true pelvis. Such tumors should be considered for preoperative chemoradiation treatment if they are T3 or higher or have node-positive disease.

Margins

In all cancer cases, adequate margins are paramount. For upper rectal cancer, getting adequate margins is not difficult and we aim for a 3–5 cm distal margin. In mid-to-low rectal cancers, 1–2 cm of negative distal margin should be ideal but 0.5–1-cm margins are acceptable. However, for sphincter preservation, we perform an intraoperative frozen section and aim for microscopically negative margins. If the tumor is very low, and a negative margin cannot be achieved, abdominoperineal resection should be done. In addition, during the resection of the mesentery, the inferior mesenteric artery (IMA) should be divided at its origin. This maximizes colonic reach for a low anastomosis and ensures adequate lymph node harvest.

Prior to starting the case, carrying out the digital rectal examination is important. Not uncommonly, you will find the lesion lower that you initially thought. Do a vaginal exam as well to make sure there is no involvement to the posterior wall of the vagina.

CO₂ Colonoscopy

An intraoperative CO₂ colonoscopy is utilized during LAR in two stages of the operation.

1. It can be used to identify the distal resection margin when resecting an endoscopically ...