Abdominoperineal resection

Abdominoperineal resection is a surgery for carcinoma of the rectum and/or anus, performed through incisions in the abdomen and perineum. APR involves the removal of the anus, rectum, and the distal portion of the sigmoid colon along with regional lymph nodes. Without an anal opening, the patient has a permanent end-colostomy from the proximal sigmoid colon created through the anterior abdominal wall, typically placed in the left lower quadrant [11-12].

2.1. Diagnosis of rectal carcinoma

In patients with rectal cancer, the most common initial presenting symptom or complaint is bleeding, followed by changes in bowel habits, diarrhea, and lower abdominal pain. A DRE may detect rectal masses located within the distal 1/3 of the rectum. A potential source of confusion from a standard DRE may arise from carcinoma of the prostate encroaching on the nearby rectum, causing similar obstructive symptoms [11]. Flexible sigmoidoscopy or colonoscopy allow for a more thorough visual characterization, location, and size of the mass, and provides an opportunity for biopsy and histological examination. Endoluminal ultrasonography has recently been shown to be a diagnostic tool for characterizing the depth of invasion of the rectal mass. Pre-operative evaluation using colonoscopy and CT and/or MRI is indicated to rule-out synchronous lesions and/or metastatic disease [13].

2.2. Indications for treatment

Classic surgical dogma throughout the 20th century states that the standard treatment for rectal tumors located less than 8cm from the anal verge is to perform an APR. Careful surgical technique must be utilized to avoid complications such as recurrence of disease due to inadequate surgical margins, anastomotic breakdown, obstruction, and re-operation. Tumors located more proximally are generally treated successfully using the standard low anterior resection with restoration of bowel continuity. Absolute contraindications for anastomosis following resection of rectal cancer are invasion of the sphincter mechanism or the anal canal. The decision to preserve the anal sphincter can be affected by several factors including: level of the tumor, depth of invasion, extent of circumferential involvement, tumor fixation, local and metastatic invasion, age, and the ability to manage a colostomy. However, advances in instrumentation and techniques often allow for some tumors in the distal rectum to be resected and anastomosis performed [13-14].

2.3. Technique

APR can be performed by a single surgeon or with a two-surgeon (abdominal and perineal) team approach. Once the patient is prepped and draped, the anus is closed using a purse-string suture. A site for the colostomy should be selected prior to incision. The surgeon may consider preoperative ureteral stent placement to aid in identification of the ureters and to facilitate repair in case of inadvertent injury. A midline infra-umbilical incision is made, and the abdomen is explored for evidence of metastatic and/or synchronous disease. Once the tumor is deemed resectable, the surgeon on the perineal side can begin dissection simultaneously. In the abdominal compartment, the sigmoid colon and rectum is mobilized by incision of the left lateral mesentery, paying careful attention to avoid the left ureter as it courses over the bifurcation of the iliac vessels. Identification and control of the inferior mesenteric artery is followed by its ligation distal to the first branch to maintain adequate blood supply to the colon segment used for the stoma. The rectum is then bluntly dissected posterior along the presac-ral space and mobilized to the tip of the coccyx. Anteriorly, the rectum is retracted away from the bladder and Denonvillier's fascia is incised to free the rectum away from the prostate to its posterior margin. The lateral ligaments that contain the middle rectal arteries are controlled and ligated. At this point the proximal sigmoid colon is divided using a stapling device and brought through the anterior abdominal wall. The colostomy is then matured.

On the perineal side, an elliptical incision is made around the anus. Dissection is then made through the sphincters and the ischiorectal fossa is entered. The presacral space is entered from below and the rectum is mobilized circumferentially. Careful dissection is performed to avoid perforation of the rectum and compromise the containment of the malignancy. The perineal dissection is completed by dividing the levator muscle on each side. The distal sig-moid and rectum can be delivered through the perineal opening. The perineal wound is closed primarily, with a closed drain left in place. The peritoneum is repaired above and the floor of the pelvis is closed [12, 14-16].

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