Objective: To find out if the ability of methylene blue given intraperitoneally to reduce surgically-induced adhesions in rats is concentration dependent.
Design: Random, controlled prospective study.
Setting: Teaching hospital, Israel.
Animals: Seventy female Wistar rats.
Interventions: Intraperitoneal adhesions were generated in rats by scraping the anterior wall of the uterine horn. They were then given either saline or serially diluted methylene blue intraperitoneally. Additional rats received identical treatments, but without the serosal damage.
Outcome measures: Graded formation of adhesions, two weeks later.
Results: In the rats treated with methylene blue 1%, adhesion formation was similar to that in sham operated rats and was significantly lower (p < 0.001) than in all other groups.
Conclusion: Methylene blue 1%, and to lesser degree 0.5%, had the best anti-adhesion potential. Lower methylene blue concentrations were only partially effective, and much high concentrations may cause adverse effects.