G&H What are the most common types of anastomoses currently being used for ileocolonic resection in Crohn’s disease?
FM There are currently 4 types of anastomoses. After resecting the terminal ileum and some ascending colon, the 2 ends can be put together in an end-to-end, end-to-side, or side-to-side fashion or in a functional antimesenteric side-to-side hand-sewn anastomosis (more commonly known as the Kono-S anastomosis). The end-to-end anastomosis and the end-to-side anastomosis do not need much explanation in that their names accurately describe their configurations. The side-to-side anastomosis, on the other hand, comes in 2 different configurations: isoperistaltic and anisoperistaltic. In the former case, the small bowel lays on top of the ascending colon in line with the flow of intestinal contents; in the latter case, the small bowel and the large bowel are put side to side, and a large enterotomy is created between them. When closed, this configuration looks like a pair of pants. The fourth anastomosis, the Kono-S anastomosis, was originally described in 2003 by the Japanese surgeon Dr Toru Kono and is being performed more and more commonly. All of these anastomoses can either be performed in a hand-sewn fashion or with the aid of a mechanical stapler, depending on the preference of the surgeon.
G&H What factors should be taken into account when choosing an anastomosis?
FM Anastomosis choice is based on 2 factors. The first one is the size of the bowel. If there is a major discrepancy in the diameter of the small bowel end and the large bowel end, it is extremely difficult to perform an anastomosis in an end-to-end fashion; hence, other configurations are selected. The second factor is the experience of the surgeon. Although surgeons may be very familiar with every type of anastomosis, each surgeon tends to prefer one anastomosis technique over others and acquires much more expertise with that type of anastomosis, which then becomes the first choice in the armamentarium of that surgeon.
Regardless of which anastomosis is performed, there is not much difference in terms of clinical or endoscopic recurrence. There is no prospective and randomized study with enough power to demonstrate that one type of anastomosis is better than another. Conversely, there is no prospective and randomized study with enough power to demonstrate that a specific subset of inflammatory bowel disease patients benefits most from one type of anastomosis vs another.
G&H What are the most common complications associated with these anastomoses?
FM There are short-term perioperative complications and long-term postoperative complications. Among the short-term complications, the most dreaded is an anastomotic dehiscence. Although the anastomosis is constructed to be waterproof at the time of surgery, it may not heal properly and start leaking intestinal content in the abdominal cavity. This may lead to peritonitis, abscesses, and septic complications. The timing of this complication is usually between 3 and 6 days after the surgical procedure, although sometimes the complication can be recognized much later than that. Another short-term complication is bleeding. This is usually self-controlled and self-limited, and it rarely requires interventions. Long-term complications mainly include stenosis, endoscopic recurrence, and strictures. Crohn’s disease can recur at the anastomosis creating a stricture, or sometimes even without recurrence, an anastomosis can narrow and stricture to the point where it is difficult for intestinal contents to go through.
G&H Are all surgeons trained in performing all of the different anastomoses?
FM Learning how to perform an intestinal anastomosis is part and parcel of residency training in general surgery. At the end of 5 years of training, surgeons should be familiar at least with the end-to-end, end-to-side, and side-to-side anastomoses, which are all similar in technical difficulty. The Kono-S anastomosis is newer and technically more challenging, so I would expect that only a few colorectal surgeons are familiar with it.
G&H How should the margins of anastomoses be determined?
FM At the time of surgery, it is important to determine whether the diseased segment requires a resection or a strictureplasty, and if a resection is needed, how much bowel needs to be resected so that the important balance between disease removal and intestinal preservation is achieved. Thus, the first question is how do surgeons recognize how much bowel to remove? This is done by inspecting the bowel, both visually and by touch. Crohn’s disease creates a thickening of the intestinal wall, partially owing to deposition of collagen and partially owing to edema. By looking and feeling, it is possible to understand where the transition is between the diseased portion and the unaffected portion of intestine. That should guide the surgeon to choose the point where to transect the bowel.
In the 1950s and 1960s, surgeons were concerned about the high recurrence rate after surgery for Crohn’s disease. In an attempt to decrease recurrences, surgeons started obtaining longer margins, sometimes guided by intraoperative biopsies to select a disease-free margin. We now know that Crohn’s disease is a panintestinal disease, and taking wider intestinal margins does not decrease the chance of recurrence. This was proven by Dr Victor Fazio from the Cleveland Clinic and colleagues in 1996 when they randomized patients to a 15-cm vs 2.5-cm proximal margin. Clinical and endoscopic recurrence in the 2 groups was similar, and the difference was not statistically significant. Taking a bigger margin, unfortunately, sacrifices more normal and working bowel, which may jeopardize patients in terms of intestinal absorption and function.
It should be mentioned that a study will start soon to look at the histology of the margins and specifically at the presence or absence of plexitis in the bowel wall. The hypothesis is that patients with plexitis would have a higher recurrence rate than patients without plexitis. This study will take some time to be completed, so at this point, there are no data suggesting that intraoperative biopsies should guide the selection of the length of the intestinal margin during a resection for Crohn’s disease.
G&H Could you discuss research that has compared different anastomoses?
FM This is a timely question because there has been a lot of interest in the Kono-S anastomosis recently. In 2011, Dr Kono and colleagues published a paper comparing patients who had undergone a Kono-S anastomosis with patients who had undergone a conventional anastomosis after resection for terminal ileitis. This study suggested that patients with a Kono-S anastomosis had less severe endoscopic recurrence at 5 years, as measured by the Rutgeerts score. Most importantly, these patients had no surgical recurrence and no need for surgical revision of the anastomosis up to 8 years, whereas as many as 15% to 20% of patients who had undergone a conventional anastomosis required a surgical resection of the anastomosis. This was a seminal study that stimulated many surgeons to embrace the Kono-S anastomosis. However, it should be noted that the level of evidence of this study is low because it was a retrospective study and the 2 groups of patients were only partially concurrent. The patients with the Kono-S anastomosis were enrolled between 2003 and 2009, whereas the patients with a conventional anastomosis had been enrolled between 1993 and 2009.
Since then, there have been 9 or 10 additional studies and a couple of meta-analyses looking at the long-term results after a Kono-S anastomosis. Unfortunately, the majority of these studies were retrospective. The only prospective study included a small number of patients, and the indications to surgery were quite heterogeneous.
G&H What are the priorities of research in this area?
FM Understanding whether the Kono-S anastomosis is superior to the other anastomoses is a priority of research. I am a principal investigator of an international multicenter study currently underway with 500 patients randomized to the Kono-S anastomosis vs a side-to-side functional end anastomosis after terminal Crohn’s ileitis attempting to answer this question. Initial preliminary data have been presented at the meeting of the European Crohn’s and Colitis Organisation this past February. At 18 months, there appears to be no difference in the endoscopic recurrence of the 2 groups. That is not surprising because Dr Kono and colleagues found a statistically significant difference in endoscopic recurrence at 5 years, not earlier. This study will continue to follow all patients for at least 5 years, possibly even 10 years, to provide a definitive answer as to whether the Kono-S anastomosis is protective of endoscopic and surgical recurrence. This study would offer the basis for a paradigm shift in the surgical treatment of Crohn’s disease if the Kono-S anastomosis is demonstrated to be protective of anastomotic recurrences.
Disclosures
Dr Michelassi has no relevant conflicts of interest to disclose.
Suggested Reading
Alibert L, Betton L, Falcoz A, et al. Does Kono-S anastomosis reduce recurrence in Crohn’s disease compared with conventional ileocolonic anastomosis? A nationwide propensity score-matched study from GETAID Chirurgie Group [KoCoRICCO Study]. J Crohns Colitis. 2024;18(4):525-532.
Cricrì M, Tropeano FP, Rispo A, et al. Impact of Kono-S anastomosis on quality of life after ileocolic resection in Crohn’s disease: an analysis from the SuPREMe-CD trial. Colorectal Dis. 2024;26(7):1428-1436.
Fazio VW, Marchetti F, Church M, et al. Effect of resection margins on the recurrence of Crohn’s disease in the small bowel. A randomized controlled trial. Ann Surg. 1996;224(4):563-571; discussion 571-573.
Fichera A, Mangrola AM, Olortegui KS, et al. Long-term outcomes of the Kono-S anastomosis: a multicenter study. Dis Colon Rectum. 2024;67(3):406-413.
Haanappel AEG, Bellato V, Buskens CJ, et al. Optimising surgical anastomosis in ileocolic resection for Crohn’s disease with respect to recurrence and functionality: two international parallel randomized controlled trials comparing handsewn (END-to-end or Kono-S) to stapled anastomosis (HAND2END and the End2End STUDIES). BMC Surg. 2024;24(1):71.
Kelm M, Reibetanz J, Kim M, et al. Kono-S anastomosis in Crohn’s disease: a retrospective study on postoperative morbidity and disease recurrence in comparison to the conventional side-to-side anastomosis. J Clin Med. 2022;11(23):6915.
Kono T, Ashida T, Ebisawa Y, et al. A new antimesenteric functional end-to-end handsewn anastomosis: surgical prevention of anastomotic recurrence in Crohn’s disease. Dis Colon Rectum. 2011;54(5):586-592.
Kono T, Fichera A, Maeda K, et al. Kono-S anastomosis for surgical prophylaxis of anastomotic recurrence in Crohn’s disease: an international multicenter study. J Gastrointest Surg. 2016;20(4):783-790.
Lin W, Lemke M, Ghuman A, et al. Effect of Kono-S anastomosis on reducing postoperative recurrence rates in Crohn’s disease: a systematic review and meta-analysis. Tech Coloproctol. 2024;28(1):127.
Shimada N, Ohge H, Kono T, et al. Surgical recurrence at anastomotic site after bowel resection in Crohn’s disease: comparison of Kono-S and end-to-end anastomosis. J Gastrointest Surg. 2019;23(2):312-319.
Tyrode G, Lakkis Z, Vernerey D, et al. KONO-S anastomosis is not superior to conventional anastomosis for the reduction of postoperative endoscopic recurrence in Crohn’s disease. Inflamm Bowel Dis. 2024;30(10):1670-1677.