Ileum Interposition for Low Rectal Anastomosis in Rectal Cancer Surgery: Too Much Effort?

Dr Zhang and colleagues 1 propose that if, in the course of low anterior resection following low vascular ligation, ie, takedown of the superior rectal artery distal to the takeoff of the left colic artery, the proximal colonic segment cannot reach the distal anastomotic limb because of tension, surgeons should consider performing an ileal interposition, using a technique similar to the creation of an ileal conduit. the authors describe a hypothetical clinical scenario where a permanent colostomy could become necessary because the proximal limb cannot reach the pelvis, which an ileal interposition could therefore avert. there are 2 basic assumptions in the contention of Dr Zhang and colleagues. the first assumption is that a high ligation of the inferior mesenteric artery is not a desirable maneuver to improve mobilization of the proximal colonic limb and achieve a tension-free anastomosis, whereas the second assumption is that an ileal interposition could work. With respect to the first assumption, the authors postulate that high ligation remains controversial in rectal cancer surgery, in particular, because a high tie could impair the blood supply of the proximal colonic limb, which would completely depend on the middle colic and marginal arteries. in this regard, it should be recognized that there are data to support this particular concern. first, there is experimental evidence from laser Doppler studies indicating that the colonic blood flow significantly decreases after ligation of the inferior mesenteric artery. furthermore, there are actual reports on the very occurrence of postoperative colonic ischemia, which is associated with significant postoperative mortality. for example, tsujinaka and colleagues described cases of proximal bowel necrosis in 6 of 302 patients undergoing high ligation in the course of oncologic resection of the sigmoid or rectum, corresponding to a 2% incidence, compared with none among 107 patients undergoing low ligation for the same indications. in addition, Park et al reported postoperative colonic ischemia in 10 of 1201 procedures for sigmoid or rectal cancer treated with high ligation, corresponding to an incidence of 0.8%. the respective mortality rates once colonic ischemia occurred were 33% (2 of 6) and 10% (1 of 10). not surprisingly, the factors significantly associated with colonic ischemia identified by the authors of these 2 reports were older age, cerebrovascular and cardiopulmonary disease. Park and colleagues actually commented that, after their experience with postoperative colonic ischemia, they had changed their technique from high to low ligation. however, there is also ample literature indicating that high tie and low tie are actually equivalent. in a recent revisitation of this time-honored debate, hida and okuno examined the contemporary reports on low and high tie and found anastomotic leak rates within comparable ranges: 1.3% to 13.3% for high tie and 6.3% to 18.5% for low tie. in particular, comparative studies have not demonstrated any significant increase in the rate of anastomotic leaks when performing a high vascular ligation, and a number of series, both old and more recent, coming from different countries and surgical practices, have reported low rates of anastomotic leakage after high ligation of the inferior mesenteric artery. although not exactly the same as postoperative colonic ischemia, anastomotic leak could be viewed as a reasonable marker of anastomotic circulation in this specific circumstance, considering that high tie facilitates a tension-free anastomosis, resulting in a 10-cm additional gain of length in the proximal anastomotic limb in comparison with traditional low tie in 1 cadaver study. it is true, as Zhang and colleagues mention, that the level of arterial ligation remains controversial in rectal cancer surgery, which also pertains to the germane issues of adequacy of lymph node harvest and risk of injury to the autonomous innervation. this long-standing controversy has even prompted some authors to suggest that a prospective randomized trial should be conducted. however, it is important to point out that the controversy concerns the optimal level of arterial ligation, in general, and not what to do if a low tie does not allow a colorectal or coloanal anastomosis. Ileum Interposition for Low Rectal Anastomosis in Rectal Cancer Surgery: Too Much Effort?