The effect of methylene blue infiltrating injection on anal pain after Milligan-Morgan surgery: A randomized controlled clinical study.

BACKGROUND

To investigate the efficacy and safety of methylene blue infiltrating injection (MBI) in alleviating postoperative pain following hemorrhoidectomy.

METHODS

In a randomized clinical trial, 60 patients with mixed hemorrhoids undergoing Milligan-Morgan surgery were divided into 2 groups: a study group (n = 30) and a control group (n = 30). Upon surgical completion, patients in the study group received an intraoperative MBI to the surgical incisions. All patients, in both groups, then received the same standard postoperative on-demand intravenous lornoxicam protocol. The primary outcome was anal pain intensity assessed by the visual analog scale scores at 6, 24, 48, and 72 hours. Secondary outcomes included limb movement score, incision edema, duration of the first postoperative defecation, supplemental analgesic consumption, length of hospital stay, hospitalization costs, and serum levels of substance P, 5-hydroxytryptamine, and prostaglandin E2.

RESULTS

No significant differences were observed in baseline characteristics. The study group exhibited significantly lower visual analog scale scores at all time points (all P < .001) and required substantially less supplemental lornoxicam (22.67 ± 17.01 mg vs 56.80 ± 9.32 mg, P < .001). Patients in the study group also had better limb movement scores, less incision edema, a shorter duration of the first postoperative defecation, a reduced hospital stay, and lower medical costs (P < .01). Serum levels of substance P, 5-hydroxytryptamine, and prostaglandin E2 were significantly lower in the study group (all P < .05). No perianal cellulitis, skin necrosis, or thrombosis occurred in either group.

CONCLUSION

MBI provides effective and safe analgesia after Milligan-Morgan surgery, significantly reducing pain, analgesic consumption, hospital stay, and cost.