A Translational Surgical Porcine Model for Postoperative Intra-Abdominal Adhesion Formation

Summary

This protocol describes a porcine model of postoperative intra-abdominal adhesion formation using Yucatan mini pigs undergoing open abdominal surgery with bowel resection. The approach reliably induces intra-abdominal adhesions and provides a platform for evaluating adhesion development and testing anti-adhesion strategies.

Abstract

A porcine model of postoperative intra-abdominal adhesion formation was established using Yucatan mini pigs. The protocol combines midline laparotomy, small bowel resection with two-layer primary anastomosis, and a unilateral, parietal peritoneal abrasion in the format of an open abdominal surgical procedure. Adhesion formation was assessed four weeks postoperatively using established gross and histologic scoring criteria, with evaluations performed by blinded observers. Adhesions developed in all animals using this model and were multifocal, involving bowel loops, between the bowel and abdominal wall, involving the peritoneum overlying other organs in the abdomen (e.g. the liver), and operative sites, with variable severity. Histological analysis at four weeks demonstrated adhesions composed predominantly of extracellular matrix, fibroblasts, and blood vessels, consistent with a remodeling-phase wound healing tissue phenotype. This model is relevant for the study of abdominal adhesion fibrosis biology and/or the translational evaluation of candidate anti-adhesion therapeutics. By integrating a clinically relevant intestinal surgical procedure with a defined peritoneal injury and a standardized assessment strategy, this protocol provides a reproducible approach for inducing and evaluating postoperative intra-abdominal adhesions in a large animal model.

Introduction

Postoperative adhesions are a major source of morbidity following abdominal and pelvic surgery, developing in up to 93% of patients^1,2, with approximately 20% requiring hospitalization within five years for adhesion-related complications^3,4. Peritoneal injury arises from abdominal surgical procedures as well as intra-abdominal irritation (infection or chemical exposure) or chronic inflammatory conditions such as inflammatory bowel disease. The resulting adhesions can lead to a wide range of clinical consequences, including recurrent bowel obstructions ....

Protocol

Ethics Statement

All porcine studies were conducted under protocols approved by the Stanford University Institutional Animal Care and Use Committee (IACUC) protocol #34052 as previously described²⁸.

1. Animal Husbandry

1. Obtain Yucatan mini pigs (recommended 9- to 12-kg, 7 to 9 weeks old) from a verified vendor. We recommend n = 4 pigs per cohort. House animals in pairs in light- and temperature-controlled rooms.
2. Provide standard porcine chow ad libitum. The animals should have access to a continuous supply of water to avoid dehydration.
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Results

The proposed porcine postoperative adhesion model (Figure 1) was combined with an adapted scoring system to grade adhesions in real time²⁸. Adhesion scoring was completed independently by 3 team members blinded to experimental conditions at the 4-week timepoint on a representative cohort of n=4 pigs; the scores were averaged for a final adhesion score per animal (Figure 2A). Intra-abdominal adhesions formed in 100% of animals evaluated on.......

Discussion

The proposed porcine adhesion model provides a clinically relevant and reliable method for modeling intra-abdominal adhesions. In contrast to focal or single-site injury models, the combination of midline laparotomy, small bowel resection with anastomosis, and standardized parietal peritoneal abrasion was intentionally selected to recapitulate the multifactorial peritoneal insults encountered during open abdominal surgical procedures. The controlled abrasion of the parietal peritoneum along the abdominal sidewall mimics .......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Animals
Female Yucatan mini pigs, 9 to 12 kg in body weight (7 to 9 weeks old)	S&S Farms		8
Surgical Supplies
DMI4000 B microscope	Leica Microsystems		Histology
Materials
Euthasol	Virbac		Euthanasia
Eosin-Y Alcoholic Stain	Azer Scientific	Cat#ES709	Histology
Frosted slides	Fisher Scientific	Cat#12-550-400	Histology
Mayer′s Hematoxylin Solution	Sigma-Aldrich	Cat#MHS80	Histology
Medications
Amoxicillin	Covetrus	59629	Infection prevention 10mg/kg PO BID x1
Ancef/Cefazolin	Covetrus	84773	Pre-op infection control 25 mg/kg IV
Atipamezole	Covetrus	82124	Sedation Reversal Agent 0.2 mg/kg
Atropine	Covetrus	74760	Bradycardia 0.04mg/kg
Bupernorphine Extended Release (ER)	Wedgewood Pharamcy		Analgesia 0.18 mg/kg IV
Carprofen - intraoperative	Dechra		Analgesia 25 mg/kg IV
Carprofen - post-operative	Dechra		Analgesia 25-50mg PO PRN
Cerenia	Zoetis		Anti-nausea 1-2 mg/kg IV once intraoperatively
Isoflurane	Dechra		Sedation
Lidocaine 2%	VetOne	V1 510212	Analgesia 2 mg/kg SQ prior to incision
Ketamine	Dechra		Anesthsia & Analgesia 12 mg/kg IM
Dobutamine	Hospira		Dosing and titration per anesthesiologist
Povidone-iodine (Betadine)	ValleyVet	12265	Antiseptic
Xylazine (Rompun)	Dechra	GW l400000	Sedation/Analgesia 2.2 mg/kg IM
Surgical Supplies
3-0 PDS (polydioxanone) Suture	Ethicon	Cat#Z316H	Anastamosis Quantity - 2
3-0 Silk Suture (Pop-off)	Ethicon	Cat#1679H	Anastamosis Quantity - 1 pack of pop off
0-0 PDS (polydioxanone) Suture	Ethicon	Cat#Z990G	Linea Alba closure Quantity - 1
3-0 Prolene Suture	Ethicon	Cat#8684G	Skin Closure Quantity - 1
Bovie Electrocautery	Grayline Medical Supply	Cat#E2516	Homeostasis and cutting
Standard set of sterile abomdinal surgical instruments with abdominal wall retractors like Army/Navy's or Richardson reactors.
3M Tegaderm + Pad	3M	Cat#3593	Surgical Dressing
High protein liquid diet	Ensure		Diet 1.5 bottles BID
Software
BioRender	Agreement number SH28Z3OOKI		Figure generation
Adobe Illustrator	Adobe	v29.8.1	Figure generation
FIJI	NIH		Figure generation
*Note: AI tools were used only for minor language and grammar edits
*BID - two times a day,  IV - intravenous, IM - intramuscular, PO - per os/ by mouth, SQ - subcutaneous, PRN - as needed