This may be the operation of choice in selected individuals with malignant lesions in the rectosigmoid or low sigmoid area in order to re-establish the continuity of the bowel. The operation is based on the premises (1) that the viability of the lower rectum can be sustained from the middle or inferior hemorrhoidal vessels and (2) that carcinoma in this region as a rule metastasizes cephalad, only rarely metastasizing 3 to 4 cm below the primary growth. It is questionable whether an anterior resection should be advised for growths occurring within 8 cm of the pectinate line. While most patients prefer restored continuity over a permanent colostomy, there is a significant risk of postoperative bowel dysfunction (post low-anterior syndrome) that is highest in patients with preoperative dysfunction such as incontinence. The absolute indications for abdominoperineal resection are discussed in Chapter 59. The ideal situation would appear to be a small tumor located at the junction of the rectum and the sigmoid. However, there are many times when the growth can be mobilized much more than anticipated, especially when the bowel is released down to the levator muscles. The exposure is another factor that may influence the surgeon for or against a low anastomosis. A low anastomosis is much easier and safer in the female than in the male, especially if the pelvic organs of the former have been removed previously. A loop ileostomy (Chapter 51) is sometimes done at the time to divert the fecal stream temporarily from the end-to-end anastomosis or to ensure decompression of an inadequately emptied colon. A side-to-side (Baker) anastomosis should be considered when there is considerable discrepancy between the sizes of the two lumina or an excess of fat that may encroach unduly upon the lumen of an end-to-end anastomosis. Most prefer a stapling device for the anastomosis (Chapter 62).
The patient is placed in the Trendelenburg position. The opposite position is useful while the splenic flexure is being mobilized.
The skin is prepared in the usual manner. A Foley catheter is inserted into the bladder.
A midline incision is made from the symphysis to a level above and to the left of the umbilicus. The liver and the upper abdomen are carefully palpated to determine the existence of any metastases. The site of the tumor is examined with special consideration as to its size and location, the amount of dilation of the bowel proximal to the growth, and the ease of exposure. In many instances the type of resection cannot be determined until the lower segment of the bowel has been mobilized.