Human-derived amniotic membrane is associated with decreased postoperative intraperitoneal adhesions in a rat model

BACKGROUND: Complications from adhesions after intra-abdominal surgery accounts for 6% of hospital admissions. Currently, hyaluronate/carboxymethylcellulose represents the main option to prevent postoperative adhesion formation. Human amniotic membrane contains inherent anti-inflammatory properties that mitigate adhesion formation. OBJECTIVE: This study aimed to evaluate adhesion generation after surgical trauma with amniotic membranes compared with standard intraperitoneal adhesion barriers. DESIGN: This study is a double-blinded, prospective evaluation. SETTING: This study was conducted at an animal research facility. ANIMALS: Forty male rats were studied. INTERVENTION: Laparotomy was performed with peritoneal disruption to the cecum. Animals were randomly assigned to 1 of 5 groups: Sham, control, saline, hyaluronic acid membrane, or amniotic membrane. Animals were euthanized at 14 days. MAIN OUTCOME MEASURES: Independent gross and histological assessments of adhesions were analyzed between groups by using adhesion scoring and microscopy. Scoring was based on the percentage of the cecum involved (0-4), vascularity of adhesions (0-3), strength (0-3), inflammation (0-3), and fibrosis (0-3). Adhered tissue was harvested for polymerase chain reaction analysis for gene regulation activity. RESULTS: All rats survived 14 days. Adhesions were observed in all animals. There were significantly fewer adhesions in the amniotic membrane group (2) versus hyaluronic acid (3) group (p = 0.01). The percentage of adhesion to the cecum was lower in the amniotic membrane group (29%) than in the hyaluronic acid group (47%, p = 0.04). Histological examination showed no significant difference between or within the 3 groups for inflammation or fibrosis. Genetic analysis of adhered tissues supported high rates of epithelialization and inhibition of fibrosis in the amniotic membrane group. LIMITATIONS: We are limited by the small sample size and the preclinical nature of the study. CONCLUSION: Human-derived amniotic membrane is effective at reducing intraperitoneal adhesion after surgical trauma and is superior to the current antiadhesion barriers. Amniotic membranes are well absorbed and demonstrate short-term safety.