Kono-S Anastomosis for Crohn's Disease: A Patient Guide

If you are preparing for ileocolic resection or have already had Crohn's surgery, you may have heard about the Kono-S anastomosis - a hand-sewn technique designed to reconnect the bowel in a way that may lower the chance of disease coming back at the surgical site.

For many of us living with Crohn's disease, surgery is not a last resort but a planned step toward feeling better. Yet one of the most frustrating realities after ileocecal resection is that Crohn's inflammation has a well-documented tendency to return right where the bowel was reconnected. The Kono-S anastomosis is a newer surgical approach that aims to change that pattern - but how strong is the evidence, and what should patients realistically expect? In this guide, we walk through the technique, the clinical trial data (including results that both support and challenge its promise), and what questions to bring to your surgeon.

Key Takeaways

• The SuPREMe-CD trial reported 6-month endoscopic recurrence of 33.3% with Kono-S versus 75% with conventional stapled side-to-side anastomosis (1)
• A larger 2025 multicenter trial (366 patients, 8 centers) found no significant difference in 12 to 18 month endoscopic recurrence between Kono-S and side-to-side anastomosis (31.6% vs 33.3%, p=0.884) (2)
• A 2024 meta-analysis found pooled surgical recurrence of 2.7% with Kono-S versus 21.0% with conventional anastomosis (RR 0.13, p less than 0.001) (4)
• Disease phenotype before surgery - stricturing, fistulating, or moderate disease activity - predicted higher recurrence risk regardless of which anastomosis technique was used (2)
• Kono-S is not a substitute for postoperative medical prevention; the technique and anti-recurrence medications work together

What Is the Kono-S Anastomosis and Why Was It Developed

The Kono-S anastomosis is an antimesenteric, functional, hand-sewn end-to-end technique for reconnecting the bowel after Crohn's resection. It was developed to address a specific anatomical problem: in conventional stapled side-to-side anastomosis, the mesenteric bowel wall - the part closest to the blood supply and fat - forms part of the new lumen, and that is precisely where Crohn's recurrence most often begins (5).

How Kono-S Differs From Side-to-Side Anastomosis

In the Kono-S approach, a longitudinal incision is made along the antimesenteric side (the side opposite the mesentery) of each bowel end, and the opening is then closed transversely, creating a wide lumen with a supporting column of interrupted sutures (5). The key difference is that the mesenteric bowel wall is excluded from the anastomotic lumen entirely. In a conventional stapled side-to-side anastomosis, the stapler fires across both mesenteric and antimesenteric walls, which means mesenteric tissue sits inside the reconnected passage.

The rationale behind this design has three parts: preserving the mesenteric vascular supply, keeping the mesentery out of the flow of intestinal contents, and reducing fecal stasis and the bacterial imbalances (dysbiosis) that may promote early inflammation at the surgical site (5).

The Problem of Postoperative Recurrence at the Anastomotic Site

Most Crohn's recurrence after ileocolic resection begins at or near the anastomosis - the very spot where the bowel was reconnected. As we covered in our guide to preventing postoperative recurrence, roughly half of patients develop endoscopic recurrence within a year, even when they feel well. The Kono-S technique was developed with the hypothesis that changing how the bowel is physically reconnected could shift those odds. But the crucial question for patients is whether the clinical evidence supports that hypothesis - and as we will see, the answer is nuanced.

What the SuPREMe-CD Randomized Trial Found

The SuPREMe-CD trial, led by Luglio and Rispo in Naples, Italy, was the first randomized controlled trial to compare Kono-S with conventional stapled side-to-side anastomosis in Crohn's patients (1). Its results generated considerable excitement in the IBD surgical community.

The 6-Month Endoscopic Recurrence Result

At 6 months, 33.3% of patients in the Kono-S group had endoscopic recurrence compared with 75% in the conventional group (1). Severe recurrence (higher Rutgeerts scores) was also lower: 15.7% with Kono-S versus 33.8% with the conventional technique (1). These are striking numbers - they suggest the Kono-S approach cut recurrence roughly in half at the early time point.

Longer-Term Surgical and Clinical Recurrence

At 36 months, surgical recurrence - meaning a patient needed another operation - was 0% in the Kono-S group versus 8.8% in the conventional group (p=0.03), and a similar pattern held at a median of 54 months of follow-up (p=0.02) (1). Clinical recurrence at 36 months was also lower with Kono-S: 19.6% versus 33.8% (1).

A related SuPREMe-CD analysis published in 2024 examined patient-reported quality-of-life outcomes after Kono-S, adding another dimension to the data beyond endoscopy findings (6). These results built a strong case for the technique - but the SuPREMe-CD trial was conducted at a single center, which meant the surgical community needed confirmation from larger, multicenter studies.

What the Newer Multicenter International Trial Suggests

In 2025, results from a larger multicenter prospective randomized trial (ClinicalTrials.gov NCT03256240) were presented. This study enrolled 366 patients across 8 international centers, making it the broadest test of Kono-S to date (2).

How the 2025 Results Differ From SuPREMe-CD

Among the 216 patients who completed follow-up colonoscopy at 12 to 18 months, endoscopic recurrence was 31.6% with Kono-S (36 of 114 patients) versus 33.3% with side-to-side anastomosis (34 of 102 patients), with p=0.884 - meaning no statistically significant difference (2). Subgroup analyses by biologic therapy exposure did not show meaningful differences between the groups either (2).

The trial did find that certain disease characteristics before surgery predicted higher recurrence risk regardless of which technique was used. Patients with stricturing (B2) or fistulating (B3) disease phenotypes and those with moderate Harvey-Bradshaw Index (HBI) activity before surgery had higher rates of recurrence (2).

What does this mean for patients? Honestly, the evidence is mixed and still evolving. The promising single-center results from SuPREMe-CD have not fully replicated at multicenter scale, and that is important context for any conversation with your surgeon. It does not mean Kono-S is ineffective - it means we do not yet have definitive proof that it is consistently superior, and individual factors like disease phenotype may matter as much as the technique itself.

What Meta-Analyses and Real-World Studies Show

When researchers pool data from multiple studies, the picture becomes clearer in some ways and murkier in others.

A 2024 systematic review and meta-analysis published in Techniques in Coloproctology combined available evidence and found pooled endoscopic recurrence of 41% with Kono-S versus 48% with conventional techniques (RR 0.86, 95% CI 0.73-1.00, p=0.05) - a modest trend that just missed statistical significance (4). However, the difference for surgical recurrence was dramatic: 2.7% with Kono-S versus 21.0% with conventional anastomosis (RR 0.13, 95% CI 0.06-0.30, p less than 0.001) (4). That is a meaningful reduction in the need for repeat surgery.

A 2022 retrospective series by Kelm and colleagues, studying 51 patients at a single institution, found comparable short-term complications between the techniques. In that series, 31.8% of Kono-S patients achieved Rutgeerts i0 - complete endoscopic remission - compared with 17.2% after conventional side-to-side anastomosis, though the difference did not reach statistical significance (3).

It is worth noting that some meta-analyses reach less favorable conclusions on clinical recurrence and safety, depending on which studies are included in the analysis. Most series consistently find that Kono-S has similar operative time, blood loss, hospital stay, and leak rate compared with conventional techniques (3), which is reassuring - the procedure does not appear to add meaningful surgical risk.

Practical Considerations: What to Ask Your Surgeon

Understanding the evidence is one piece of the puzzle. The other is having a productive conversation with your surgical team about whether Kono-S makes sense for your situation.

Is Kono-S Available Where You Are Treated

Kono-S is a hand-sewn technique that requires surgeon training and experience with its specific configuration (5). Not every colorectal surgeon has been trained in it, and not every hospital offers it. This is an important practical starting point: ask whether your surgeon has performed the Kono-S anastomosis before and, if so, how many times. Surgical outcomes are often closely tied to the volume and experience of the operating team.

If Kono-S is not available at your center, that does not mean your outcome will be worse - the multicenter trial showed equivalent endoscopic recurrence rates at 12 to 18 months between the two techniques (2). A well-performed conventional anastomosis by an experienced IBD surgeon remains a sound approach.

Who Might Benefit Most

Based on the current evidence, patients who might consider discussing Kono-S with their surgeon include those scheduled for their first ileocecal resection, particularly at IBD-dedicated surgical centers where the technique is routinely performed.

But equally important is understanding that disease phenotype - whether your Crohn's is stricturing, fistulating, or inflammatory - appears to influence recurrence risk regardless of which anastomosis technique is used (2). A conversation with your surgeon and gastroenterologist about your specific disease pattern is just as important as the choice of technique.

And here is the point that cannot be overstated: postoperative recurrence prevention still requires an anti-recurrence medication plan (typically a biologic or immunomodulator), risk-stratified endoscopic follow-up, and lifestyle measures such as smoking cessation. Even in the best trial results, roughly a third of Kono-S patients still had endoscopic recurrence by 6 to 18 months - so vigilance matters regardless of how the bowel was reconnected.

What This Means for Patients Facing Ileocolic Resection

For patients preparing for or recovering from Crohn's surgery, here is how to think about the Kono-S evidence in practical terms.

The strongest signal so far is for reduced severe endoscopic recurrence and reduced surgical re-resection - the 2024 meta-analysis showed a dramatic drop in the need for repeat surgery with Kono-S (4). That is clinically meaningful and worth discussing with your surgeon. At the same time, the largest multicenter trial to date did not confirm a significant advantage in overall endoscopic recurrence at 12 to 18 months (2), which tempers the earlier single-center enthusiasm.

Kono-S is a reasonable option to discuss, particularly if you are being treated at an IBD-dedicated center where surgeons have experience with the technique. It is not a substitute for medical prevention after surgery - the two work together. And for patients with stricturing disease who might also benefit from bowel-sparing approaches, the conversation about surgical technique is even more nuanced.

Shared decision-making with your surgeon, gastroenterologist, and - when relevant - an IBD-focused multidisciplinary team is the best path forward. Bring the questions, bring the evidence, and remember that no single technique eliminates recurrence on its own. What gives you the best odds is the combination of skilled surgery, proactive medical therapy, structured monitoring, and taking care of yourself after the operation.

Frequently Asked Questions

Is the Kono-S anastomosis safer than a conventional stapled anastomosis?

Studies consistently show that Kono-S has similar operative time, blood loss, hospital stay, and leak rates compared with conventional stapled techniques (3). It does not appear to add meaningful surgical risk. The main difference is in how it reconnects the bowel and its potential effect on recurrence, not in short-term safety.

Does Kono-S eliminate the need for medications after surgery?

No. Even with the most optimistic trial results, roughly a third of Kono-S patients developed endoscopic recurrence within 6 to 18 months (1)(2). Postoperative anti-recurrence medications - typically a biologic or immunomodulator - remain essential regardless of which anastomosis technique is used. The technique and the medication plan work together.

Can Kono-S be performed laparoscopically?

The Kono-S anastomosis is a hand-sewn technique that requires an extracorporeal (outside the body) step. Most surgeons perform the resection laparoscopically and then bring the bowel ends out through a small incision to create the Kono-S connection. This is a common approach and does not require a fully open operation.

How do I know if my surgeon is experienced with Kono-S?

Ask directly. Reasonable questions include how many Kono-S anastomoses they have performed, whether they trained at a center where the technique is routinely used, and what their own outcomes have been. IBD-dedicated surgical centers and academic medical centers are more likely to have surgeons experienced with this approach.

Does my disease type affect whether Kono-S is better for me?

Yes, your disease phenotype matters significantly. The 2025 multicenter trial found that stricturing (B2) and fistulating (B3) disease patterns and moderate disease activity before surgery predicted higher recurrence risk regardless of which anastomosis technique was used (2). Discuss your specific disease pattern with your surgeon and gastroenterologist.

Is Kono-S available outside major academic centers?

Currently, Kono-S availability is concentrated at IBD-specialized surgical centers and academic hospitals, because the technique requires specific training. However, its availability is growing as more surgeons learn the approach. If your local surgeon does not perform Kono-S, a conventional side-to-side anastomosis performed by an experienced surgeon remains a well-supported option.

What should I prioritize if Kono-S is not available where I live?

Focus on the factors with the strongest evidence for preventing recurrence: quitting smoking if you smoke, starting postoperative anti-recurrence medication as recommended by your gastroenterologist, and completing your follow-up colonoscopy at 6 to 12 months after surgery. These measures have been shown to lower recurrence risk regardless of the anastomosis technique used.

References

1. Luglio G, Rispo A, et al. P522 Kono-S anastomosis reduces endoscopic and surgical post-operative recurrence in Crohn's disease. The SuPREMe-CD Trial Update. Journal of Crohn's and Colitis, 2023. Read study
2. OP16 Postoperative endoscopic recurrence after ileocecal resection for Crohn's disease with Kono-S or side-to-side functional end anastomosis: 12-18 months follow-up results from a Multicenter Prospective Randomized Trial (NCT03256240). Journal of Crohn's and Colitis, 2025. Read study
3. Kelm M, Reibetanz J, Kim M, et al. Kono-S Anastomosis in Crohn's Disease: A Retrospective Study on Postoperative Morbidity and Disease Recurrence. Journal of Clinical Medicine, 2022. Read study
4. Effect of Kono-S anastomosis on reducing postoperative recurrence rates in Crohn's disease: a systematic review and meta-analysis. Techniques in Coloproctology, 2024. Read study
5. Preventing recurrent Crohn's Disease after surgery: the Kono-S anastomosis. BJS Academy Continuing Surgical Education, 2023. Read article
6. Clark DA, Smith N, Clark I, et al. Time for an Australian and New Zealand randomized controlled trial to study the modified Kono S anastomosis. ANZ Journal of Surgery, 2022. Read study