Kono-S anastomosis for recurrent ileocolic anastomotic stricture in Crohn’s disease: a case report

Abstract

Background and importance:

Crohn’s disease frequently requires surgical intervention due to strictures and bowel obstruction, yet postoperative recurrence remains common. Anastomotic stenosis represents a significant cause of re-intervention.

Presentation of case:

We present a 32-year-old man with Crohn’s disease who developed a symptomatic ileocolic anastomotic stricture 8 months after ileocecal resection. Endoscopic evaluation and computed tomography confirmed critical stenosis. Two endoscopic balloon dilations provided only temporary relief. Redo resection with Kono-S anastomosis was performed, with resection of approximately 20 cm of bowel.

Clinical discussion:

The Kono-S anastomosis is a hand-sewn antimesenteric technique designed to preserve luminal caliber and reduce recurrence by limiting mesenteric influence. It may be a useful option in redo surgery following a failed conventional stapled anastomosis, particularly in complex recurrent cases.

Conclusion:

This case sheds light on the technical feasibility of the Kono-S anastomosis in managing recurrent ileocolic anastomotic stricture in Crohn’s disease. However, as this is a single-case report, further evidence is needed to confirm its long-term safety and efficacy.

Introduction

Crohn’s disease is a chronic inflammatory bowel disease characterized by a relapsing course and a substantial risk of complications, such as strictures, fistulas, and bowel obstruction. Genetic susceptibility and dysregulated innate and adaptive immune responses to intestinal microbiota play a central role in disease pathogenesis[1].

Treatment strategy for Crohn’s disease is based on factors such as the patient’s disease pattern, severity, and other medical conditions. The treatment goal is to achieve a balance between effectiveness, side effects, and long-term risks[2]. Despite recent therapeutic advances, a substantial proportion of patients with Crohn’s disease develop complications such as strictures, bowel obstruction, perforation, or penetrating disease behavior[3].

HIGHLIGHTS

• Kono-S anastomosis is a feasible option for recurrent ileocolic anastomotic stricture in Crohn’s disease.

• Redo surgery after a failed endoscopic dilatation can be safely performed using this technique.

• The Kono-S configuration may help preserve luminal patency and reduce early recurrence.

The Montreal classification is an international standard for phenotyping Crohn’s disease based on disease behavior, localization, and age of the patient, which impacts prognosis and treatment choices[4]. Well-established risk factors regarding postoperative recurrence in Crohn’s disease include genetic and environmental factors, such as smoking, which significantly increases the risk of recurrence and poor clinical outcomes by triggering inflammation and fibrosis[5].

One of the most common complications of Crohn’s disease is the development of strictures and/or fistulas, which lead to a significant portion of partial or complete obstruction[6]. Surgery is indicated in Crohn’s disease patients with symptomatic obstructions that do not respond to endoscopic dilatation or specific therapy. It is of great importance for the long-term survival of the patients to consider the type of surgical anastomosis that will be performed[7]. Various anastomotic configurations have been proposed to mitigate the recurrence risk of stenosis; however, no conventional technique has reliably demonstrated clear superiority in preventing recurrence[8]. In the last few decades, new surgical technical aspects have been developed to improve patient outcomes. These new anastomoses aim to keep the mesenteric side away from the anastomosis, where recurrence often appears[9].

The Kono-S anastomosis is a hand-sewn, antimesenteric, functional end-to-end connection designed to reduce the risk of postoperative Crohn’s disease recurrence by maintaining the natural shape of the intestinal lumen and limiting mesenteric effects on healing. It has been hypothesized that this configuration counteracts fibrotic narrowing and distortion at the mesenteric side, where Crohn’s disease recurrence most frequently originates^[10,11^].

The first clinical introduction of the Kono-S anastomosis was in Japan in 2003, and since then, it has gained international adoption. Although early studies have reported favorable outcomes associated with the Kono-S anastomosis, the relationship between anastomotic configuration and long-term recurrence remains controversial[12]. This case highlights the potential role of the Kono-S anastomosis in redo surgery for recurrent ileocolic anastomotic stricture following conventional stapled anastomosis, emphasizing its clinical relevance in challenging cases.

Presentation of case

A 32-year-old man with a diagnosis of Crohn’s disease, established in 2022, initially presented with symptoms of bowel obstruction due to stenosis of the terminal ileum. The disease was classified according to the Montreal classification as A2 L1 B2. An ileocecal resection with a primary side-to-side stapled ileocolic anastomosis was performed. The postoperative course was uneventful, and the patient was started on biological therapy with an anti-tumor necrosis factor (TNF) agent. No known risk factors for disease recurrence, such as smoking, were reported by the patient. Eight months after the primary surgery, the patient developed recurrent obstructive symptoms. Colonoscopic evaluation demonstrated a stenosis at the level of the ileocolic anastomosis (Fig. 1). Two endoscopic balloon dilations were performed at 6-month intervals, resulting in only temporary clinical improvement. The endoscopic appearance was classified using the Rutgeerts score, indicating a grade i2a lesion, which is associated with a high risk of clinical recurrence.

Figure 1.

Colonoscopic image of the ileocolic anastomosis showing a severe anastomotic stricture with a pinpoint residual lumen. The arrow marks the anastomotic stricture.

Computed tomography demonstrated critical narrowing at the anastomotic site with proximal bowel dilatation, consistent with recurrent anastomotic stricture (Fig. 2) Due to persistent symptoms and failure of endoscopic management, surgical intervention was indicated.

Figure 2.

Abdominal CT showing severe stenosis at the ileocolic anastomosis with proximal bowel dilatation. The arrow marks the anastomotic stricture.

At reoperation, a severely deformed segment of bowel was identified at the site of the previous ileocolic anastomosis. A complete anastomotic stenosis was confirmed intraoperatively. Approximately 20 cm of bowel, including the previous anastomosis, was resected. Both proximal and distal segments were preserved with adequate vascular supply.

Intestinal continuity was restored using a hand-sewn Kono-S anastomosis (Fig. 3A). The anastomosis was constructed in an antimesenteric fashion using 4-0 polydioxanone sutures (Fig. 3B, 3C)

Figure 3.

Intraoperative views of the Kono-S anastomosis. (A) Construction of the anastomosis in an antimesenteric functional end-to-end fashion. (B) Completion of the posterior wall using a continuous 4-0 polydioxanone suture. (C) Completion of the anterior wall of the anastomosis.

Histological examination of the resected specimen demonstrated transmural inflammation and fibrosis consistent with Crohn’s disease. The postoperative course was uneventful, and the patient was discharged in good general condition. Due to the aggressive behavior of the disease and suboptimal clinical response to anti-TNF therapy, the patient was switched to interleukin-23 therapy. This change, combined with individualized dietary recommendations focused on reducing inflammation and supporting intestinal healing, constitutes an essential part of comprehensive care to prevent recurrence.

During follow-up exceeding 12 months, no clinical symptoms of recurrence were observed. Radiological evaluation did not demonstrate evidence of recurrent stenosis.

Discussion

This report describes a patient who developed anastomotic stenosis after a conventional stapled ileocolic anastomosis, initially treated endoscopically with limited effect. Fibrotic recurrence after intestinal resection remains common in clinical practice. The clinical manifestation of postoperative stenosis can sometimes lead to serious symptoms, which are indications for further surgery^[13,14^]. This case report illustrates the versatility of the Kono-S anastomosis in the surgical management of Crohn’s disease. In this patient, the technique was applied in a complex clinical setting, showing its feasibility and technical adaptability.

The favorable early outcome observed, namely the absence of anastomotic leakage and preservation of luminal patency, is consistent with findings from retrospective cohort studies reporting low complication rates and maintained anastomotic caliber following Kono-S anastomosis[15]. Proposed mechanisms underlying these outcomes include preservation of a wide lumen and stabilization of the mesenteric border, where postoperative recurrence commonly originates. The “Supporting Column” created by the Kono-S technique provides a reinforced structure on the mesenteric side, which is thought to prevent luminal narrowing by mechanically stabilizing this vulnerable area and limiting fibrotic remodeling. This architectural feature is increasingly recognized as a significant factor in reducing recurrence rates compared to traditional anastomoses^[16,17^].

Despite encouraging short-term results, conclusions regarding long-term superiority over conventional anastomotic techniques cannot be drawn from a single case. Although some studies have reported reduced recurrence rates after Kono-S anastomosis, symptomatic recurrence after intestinal resection for Crohn’s disease remains frequent, reflecting the multifactorial nature of disease recurrence^[15,18^]. Postoperative recurrence in Crohn’s disease is commonly classified as endoscopic, clinical, or surgical recurrence. Endoscopic lesions frequently precede symptoms and may develop within the first year after resection. This discrepancy between mucosal recurrence and clinical manifestation complicates the interpretation of surgical outcomes and highlights the need for standardized postoperative surveillance^[7,14^].

Conventional side-to-side stapled anastomoses remain widely performed due to their technical simplicity and shorter operative time. However, concerns persist regarding mesenteric involvement at the staple line and potential luminal distortion over time. Comparative analyses have not demonstrated unequivocal superiority of one configuration over another, which has stimulated interest in alternative techniques such as the Kono-S anastomosis^[8,12^]. Recent meta-analyses have further evaluated the safety and efficacy of the Kono-S technique. Cathomas et al analyzed 12 studies, including 820 patients, and reported low surgical recurrence and acceptable morbidity[19]. Similarly, Baloyiannis et al demonstrated reduced reoperation rates and lower anastomotic leakage compared with conventional techniques, although overall morbidity remained comparable between groups[20]. Two international multicenter randomized controlled trials are currently evaluating hand-sewn anastomotic techniques, including the Kono-S configuration, in comparison with stapled side-to-side anastomoses, with recurrence, functional outcomes, and healthcare utilization as primary endpoints[21].

In our case, the absence of early recurrence and the satisfactory postoperative course suggest that the Kono-S configuration is technically feasible and a safe method in the setting of redo surgery for anastomotic stricture. Nevertheless, given that this is a single-case report, the conclusion about safety and efficacy should be considered preliminary. Further prospective, larger-scale studies with long-term follow-up are required to clarify the impact of this technique on Crohn’s disease surgical recurrence.

Conclusion

The Kono-S anastomosis represents a feasible reconstructive option in patients with recurrent ileocolic anastomotic stricture due to Crohn’s disease. In this case, redo resection with Kono-S reconstruction was performed safely and resulted in favorable short-term outcomes. Larger prospective studies and randomized trials are necessary to clarify the long-term impact of this technique on surgical recurrence.

This case report has been reported in line with the SCARE 2023 criteria[22].

Ethical approval

Ethical approval was not required for this case report in accordance with institutional policies.

Consent

Written informed consent was obtained from the patient for publication of this case report and the accompanying images.

A copy of the written consent is available for review by the Editor-in-Chief of this journal upon request.

Sources of funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Conflicts of interest disclosure

The authors declare no conflicts of interest.

Author contributions

MZ: Study concept and design, data collection, and drafting of the manuscript. VK: Data analysis and interpretation, critical revision of the manuscript. IG: Supervision, final approval of the manuscript. All authors have approved the final version of the manuscript.

Research registration unique identifying number (UIN)

Not applicable.

Guarantor

Ivan Genov.

Provenance and peer review

Not commissioned; externally peer-reviewed.

Data availability statement

Data sharing is not applicable to this article, as no datasets were generated or analyzed.

AI declaration

No artificial intelligence (AI) tools were used in the preparation of this manuscript.

Acknowledgements

Not applicable.