Effectiveness of methylene blue as a local anesthetic and analgesic in perianal Operations: a prospective double-blind randomized control trial

Perianal operations often result in significant postoperative pain, which negatively affects patient comfort and recovery. The search for effective pain relief options has led to the investigation of methylene blue, a biological stain with potential analgesic properties. This study aimed to evaluate the analgesic and anaesthetic effects of a mixture of methylene blue and lidocaine compared to plain lidocaine in the management of postoperative pain after perianal operations. A prospective, double-blinded, randomized controlled trial was conducted at a single center between 2015 and 2023. A total of 727 adult patients undergoing perianal surgical operations were randomly assigned to two groups: the experimental group received a solution of methylene blue and lidocaine, while the control group received plain lidocaine. Pain levels were assessed using the Visual Analog Scale (VAS), and follow-up visits and phone calls were conducted. The analysis included 727 participants who underwent operations for perianal abscess, fistula, fissure, and haemorrhoid. The participants were divided into the experimental group (N=329) and the control group (N=398). The data were analyzed using SPSS version 28, applying descriptive and inferential statistical methods. The study included a total of 727 patients, with a mean age of 47 years (ranging from 18 to 90 years). Among the patients, 56.5% were males and 43.5% were females. The two groups showed significant differences in terms of postoperative analgesic use and pain-free days (p<0.001). Specifically, the methylene blue group had lower Visual Analog Scale (VAS) scores compared to the control group (p<0.05, p<0.001), respectively. No significant differences in immediate complications were observed between the two groups. Methylene blue is an effective intervention for reducing postoperative pain after perianal operations, potentially decreasing the need for additional pain medication. The findings of this study suggest that methylene blue has a promising role in pain management without an increase in complications.