Perioperative management - Rectal resection, open, low anterior with total mesorectal excision (TME)

This surgical procedure is employed in resectable rectal cancer with a distal mural margin of 1–2cm, as measured with rigid rectoscopy from the distal edge of the tumor to the dentate line.

Abdominoperineal resection of the rectum is indicated for carcinoma of the distal rectum where this safety margin cannot be ensured or in which there is also invasion of the sphincter. In early cancer (clinical category T1, N0, G1 or G2), the guidelines allow local excision as an alternative to low anterior resection of the rectum (LAR).

Depending on the level of the anastomosis proximal to the sphincter, reconstruction after anterior and low anterior resection may be performed as colorectal, coloanal or colonic pouch-anal anastomosis.

Limited operability, for instance because of major comorbidity (e.g., major pulmonary disease, heart failure, cirrhosis of the liver, etc.). Whether this comorbidity is a contraindication to surgery must be assessed for each patient individually.

Major preexisting anal incontinence. If the medical history points to significant anal incontinence before the emergence of the rectal cancer, it should be discussed with the patient whether a Hartmann operation with low rectal stump or abdominoperineal rectal resection with end descendostomy might not be the more advisable surgical procedure. It should be noted that a well-cared-for stoma offers a better quality of life than major anal incontinence without a stoma.

When there is invasion of the sphincter or an inadequate mural margin between the distal edge of the tumor and the resection line, low anterior resection is also contraindicated, and abdominoperineal resection should be performed instead. The same applies to situations where, on gross or microscopic (frozen section) inspection, tumor cells are present at the distal resection margin of specimen, despite the resection having been performed at the level of the dentate line. In this case, too, the principles of oncologic radicality require conversion to abdominoperineal resection.

• Clinical examination, including digital rectal examination. This already allows assessment of the distance between the tumor and the anocutaneous line and how mobile the tumor is regarding the adjacent tissues.
• Rectoscopy: Only rigid rectoscopy allows accurate tumor localization, ideally measured as the distance between the distal edge of the tumor and the dentate line. 
• Biopsy: Preoperative histological confirmation of the tumor diagnosis is mandatory. Several biopsies should be taken, as cancer often arise from adenomas.
• Complete colonoscopy: Complete colonoscopy is required to diagnose and resect any additional adenomas or rule out a synchronous second cancer. If the tumor cannot be passed due to stenosis, an air contrast barium enema study, intraoperative colonoscopy or virtual colonoscopy would be alternative modalities.
• Endoluminal ultrasonography (EUS): Allows assessment of the clinical T-category with high sensitivity and specificity; the T category is important because it is one of the factors determining possible neoadjuvant therapy. In addition, in some patients EUS allows identification of lymph nodes raising suspicion because of their size.
• Abdominal ultrasonography. The liver is studied by ultrasound to rule out hepatic metastasis. Alternatively, this modality may be substituted by CT or MRI studies of the abdomen and pelvis.
• Pelvic CT: According to present studies, EUS determines the T stage more precisely than CT or MRI. However, T4 stages are often difficult to assess by EUS. Here, computerized tomography allows a more accurate diagnosis. Also, in mesorectal invasion CT can help estimate the distance of the tumor from the inner lamella.
• Magnetic resonance imaging: MRI allows in an even clearer way to delineate a tumor invading the mesorectum from the inner lamella and allows very accurate measurement of the distance between this structure and the tumor.
• Positron emission tomography (PET): Usually, this modality is not part of the primary diagnostic work-up in rectal cancer, but it is quite suitable to differentiate locoregional recurrence from scars and inflammatory changes.

• Obtain written informed consent
• Inform patient about stoma care and mark a (fallback) stoma site.
• Shave the surgical field
• Depending on the clinical protocol of the institution, lavage the bowel with Klean-Prep® solution or abstain from intestinal preparation, but at least preoperative bowel movement by enema.
• Assess the patient’s operability, if necessary consult with other specialists.
• Provide possible for blood transfusions
• Present patient to anesthesiologist

• Anastomotic failure
• Wound infection/intraabdominal abscess/infection
• Secondary bleeding
• Thrombosis / embolism
• Injury of intraabdominal structures, in particular ureter, spleen
• Bladder and sexual dysfunction
• Impaired postoperative fecal continence
• If necessary, discuss and document possible expansion of the operation depending on the intraoperative findings (e.g., abdominoperineal resection in very low cancer)