Chapter 26 Abdominal Perineal Resection with Colostomy
INTRODUCTION
An abdominal perineal resection (APR) is the complete removal of the rectum and anus. The most common indication for surgery is adenocarcinoma of the lower rectum, when performing a primary anastomosis is not feasible. When APR is done for cancer, obtaining a negative circumferential margin is critical, so the dissection is wide to provide adequate oncologic clearance. Sometimes, the rectum and anus need to be removed for benign conditions. Under these circumstances, the dissection can be closer to the rectal wall, which may help prevent complications. For the purpose of this discussion, it is assumed that the indication for surgery is cancer and the technical points will stress appropriate oncologic technique. These principles are generally applicable to benign conditions as well. However, on occasion, there are differences in patients with benign disease, and this is noted in the text.
INDICATIONS
This is a partial list of surgical indications for an APR and colostomy. These procedures involve the complete removal of the rectum and anus and the creation of an end colostomy.
OPERATIVE PROCEDURE
Abdominal Perineal Resection
An APR consists of two separate dissections. When performed by one operating surgeon, the abdominal dissection is completed first and then the surgeon will reposition himself or herself and perform the perineal dissection. Because there are two distinct areas of dissection, some surgeons advocate a synchronous approach, utilizing two surgeons and a simultaneous abdominal and perineal dissection.1 Such an approach decreases operative time and can help both surgeons during a difficult case.
Abdominal Dissection
The abdominal portion of the procedure is similar to a very low anterior resection. It is helpful to continue the abdominal dissection as low as possible, preferably all the way to the pelvic floor and below the coccyx. As one gets lower in the pelvis, the surgeon needs to be cognizant of the tumor location and make sure she or he does not cone in on the rectum, leaving a positive circumferential radial margin. Otherwise, the abdominal dissection is the same as for a low anterior resection. Therefore, the complications and anatomy are also similar. The reader is referred to Section III, Chapter 25, Low Anterior Resection, for complications associated with the abdominal portion of this procedure.
Perineal Dissection
Upon completion of the abdominal dissection, the surgeon must reposition himself or herself for the perineal dissection. An elliptical incision is made around the anus, approximately 2 to 3 cm from the anal verge (Fig. 26-1). Once the skin is incised, the dissection is greatly facilitated by the use of a self-retaining retractor (Fig. 26-2). The incision is then carried deeper into the ischiorectal fossa bilaterally (Fig. 26-3). No vital structures are located in the posterior or lateral positions, so dissection in this area is safe and should be continued more deeply using electrocautery. The inferior rectal artery does pass through the ischiorectal fossa and may result in some minor bleeding. This artery can usually be controlled with electrocautery but does occasionally require ligation. As the dissection is carried posteriorly, there is a tendency for the operating surgeon to travel too far and get behind the coccyx (Fig. 26-4). Therefore, careful palpation of the coccyx is critical to guide the surgeon’s dissection above the coccyx. Once the coccyx is clearly identified (Fig. 26-5), a fibrous band extends from the coccyx in the midline position. This is the anococcygeal ligament and needs to be divided. The surgeon is now ready to enter the peritoneal cavity just above the coccyx. This is best done with an assistant placing a hand behind the rectum all the way to the coccyx from the abdominal cavity. Then the operating surgeon should be able to palpate the assistant’s finger. Mayo scissors are then used to poke through the pelvic floor, just above the coccyx (Fig. 26-6). This hole is widened, which allows the operating surgeon to insert a finger into the peritoneal cavity and hook the levator ani muscles. Using electrocautery, these muscles can be divided in both directions (Fig. 26-7). Once 75% of this dissection is complete, the top of the rectum can be grasped and pulled through the perineal defect (Fig. 26-8). This helps define the anterior plane of dissection, which can be the most challenging. With a hand behind the rectum, the anterior plane between the rectum and the prostate or the vagina is developed (Fig. 26-9). In a man, palpation of the Foley catheter can help define this plane (Fig. 26-10). In a woman, a finger in the vagina can be advantageous. The specimen is finally freed and removed. The perineal wound is then closed, using several layers of an absorbable suture, and the skin closed with a subcuticular stitch.
Figure 26-1 Perineum in a patient with rectal cancer. Purple line demonstrates the location of the incision for malignant disease, which is outside the external sphincter.
Figure 26-2 Final appearance after removal of the rectum and anus. Forceps point to the posterior wall of the prostate.
Figure 26-3 Perineum in a patient with Crohn’s disease. A self-retaining retractor is in place. Yellow dotted line demonstrates the location of the incision for an intersphincteric dissection. This dissection is appropriate for benign disease.
Figure 26-7 APR, posterior dissection. The surgeon is about to use Mayo scissors to poke into the peritoneal cavity just above the coccyx.
Urethral Injury
• Consequence
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