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. 2025 Feb 27;17(2):94270.
doi: 10.4240/wjgs.v17.i2.94270.

Comparative study of cylindrical vs circular ring magnets for colonic anastomosis in rats

Miao-Miao Zhang  1   2   3 , Ai-Hua Shi  2   3 , Oliver J Muensterer  4 , Ibrahim Uygun  5 , Yi Lyu  1   2   3 , Xiao-Peng Yan  1   2   6
Affiliations

Comparative study of cylindrical vs circular ring magnets for colonic anastomosis in rats

Miao-Miao Zhang et al. World J Gastrointest Surg. .

Abstract

Background: Magnetic compression anastomosis (MCA) offers a simple and reliable technique for inducing anastomoses at any point along the digestive tract. Evidence regarding whether the design of the MCA device influences the anastomosis effect is lacking.

Aim: To investigate any difference in the side-to-side colonic anastomosis effect achieved with cylindrical vs circular ring magnets.

Methods: We designed cylindrical and circular ring magnets suitable for side-to-side colonic anastomosis in rats. Thirty Sprague-Dawley rats were randomly divided into a cylindrical group, circular ring group, and cylindrical-circular ring group (n = 10/group). Side-to-side colonic anastomosis was completed by transanal insertion of the magnets without incision of the colon. Operation time, perioperative complications, and magnet discharge time were recorded. Rats were euthanized 4 weeks post-operatively, and anastomotic specimens were obtained. The burst pressure and anastomotic diameter were measured sequentially, and anastomosis formation was observed by naked eye. Histological results were observed by light microscopy.

Results: In all 30 rats, side-to-side colonic anastomosis was completed, for an operation success rate of 100%. No postoperative complications of bleeding and intestinal obstruction occurred, and the postoperative survival rate were 100%. The operation time, magnet discharge time, anastomotic bursting pressure, and anastomotic diameter did not differ significantly among the three designs (P > 0.05). Healing was similar across the groups, with gross specimens showing good anastomotic healing and good mucosal continuity observed on histological analysis.

Conclusion: This study found no significant difference in the establishment of rat side-to-side colonic anastomosis with the use of cylindrical vs circular ring magnets.

Keywords: Colonic anastomosis; Magnet; Magnetic compression anastomosis; Magnetosurgery; Rats.

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Conflict of interest statement

Conflict-of-interest statement: All the authors report no relevant conflicts of interest for this article.

Figures

Figure 1
Figure 1
Magnets. A: Front views of the cylindrical magnet and circular ring magnet; B: Side view of the magnets once attracted; C: Magnetic field viewing film showing the magnetic field distributions for the cylindrical magnets and circular ring magnets; D: The magnetic force curve.
Figure 2
Figure 2
Schematic of the surgical procedure. A: A magnet is inserted through the anus into the proximal portion of the colon; B: Another magnet is inserted through the anus to the distal end of the colon; C: The two magnets in the colon are attracted; D: The magnets are discharged after the side-to-side colonic anastomosis is established. DM: Daughter magnet; PM: Parent magnet.
Figure 3
Figure 3
Surgical procedure. A: For the cylindrical group, a cylindrical daughter magnet (DM) and cylindrical parent magnet (PM) were placed in the proximal and the distal end of the colon (black arrows); B: The two cylindrical magnets attracted together (yellow circle); C: For the circular group, a circular ring-DM and circular ring-PM were placed in the proximal and distal ends of the colon (black arrows); D: The two circular ring magnets attracted together (yellow circle); E: For the cylindrical–circular group, a cylindrical-DM and a circular ring-PM were placed in the proximal and distal ends of the colon, respectively (black arrows); F: The cylindrical-DM and circular ring-PM attracted together (yellow circle). DM: Daughter magnet; PM: Parent magnet.
Figure 4
Figure 4
Measurement of anastomotic parameters. A: Measurement of the burst pressure of the anastomosis; B: Measurement of the anastomotic diameter.
Figure 5
Figure 5
Anastomotic gross specimens. A-D: Gross specimen of colon anastomosis from the cylindrical group; E-H: Gross specimen of colon anastomosis from the circular ring group; I-L: Gross specimen of colon anastomosis from the cylindrical–circular ring group.
Figure 6
Figure 6
Representative images of histological staining of the colonic anastomosis. A and B: Hematoxylin & eosin (H&E) and Masson trichrome staining of the anastomosis in the cylindrical group; C: H&E and Masson trichrome staining of the necrotic tissue between the daughter magnet (DM) and parent magnet (PM) in the cylindrical group; D and E: H&E and Masson trichrome staining of the anastomosis in the circular ring group; F: H&E and Masson trichrome staining of the necrotic tissue between the DM and PM in the circular ring group; G and H: H&E and Masson trichrome staining of the anastomosis in the cylindrical–circular ring group; I: H&E and Masson trichrome staining of the necrotic tissue between the DM and PM in the cylindrical–circular ring group.
Figure 7
Figure 7
Finite element simulation analysis. A: Stress distribution after intestinal wall compression in the cylindrical group; B: Stress distribution after intestinal wall compression in the circular ring group; C: Stress distribution after intestinal wall compression in the cylindrical–circular ring group.
See this image and copyright information in PMC

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