Effects of Different Doses of Intraperitoneal Lidocaine on Intra-operative Pain Relief During Mini-laparotomy Postpartum Tubal Ligation: A Three-group Randomized Controlled Trial

Abstract

Objective: To determine the efficacy of 50 mg and 100 mg intraperitoneal lidocaine (IPL) compare with placebo in reducing intraoperative pain during postpartum mini-laparotomy tubal ligation.

Materials and Methods: In this randomized, double-blind trial, 102 postpartum women were allocated equally to receive 20 mL of normal saline, 50 mg lidocaine, or 100 mg lidocaine intraperitoneally                    (July 2024 to July 2025). All participants received 10 mg intramuscular morphine 30 minutes before                surgery and local 15 ml of 1% lidocaine with epinephrine. Pain at four intra-operative points was                 analyzed using a linear mixed-effects model with a random intercept for each participant.

Results: Ninety-six women completed the study (100-mg group, n = 33; 50-mg group, n = 34;                  placebo, n = 29). Baseline characteristics, including age and body mass index, were comparable among the three groups. Pain at 1 minute after instillation did not differ among groups  (p = 0.395). Compared with placebo, mean differences (placebo minus lidocaine) (95% CI) in NRS pain were +1.43 (0.08–2.78) and +3.11 (1.75–4.48) at first ligation, +2.27 (0.91–3.62) and +4.60 (3.23–5.96) at second ligation, and +1.71 (0.35–3.06) and +3.39 (2.03–4.75) after skin closure for 50 mg and 100 mg, respectively                     (all p < 0.05). Pain scores were significantly lower with 100 mg than with 50 mg (p ≤ 0.03). Four            participants (4.17%) reported mild dizziness without serious events.

Conclusion: Intraperitoneal lidocaine (50 and 100 mg) significantly reduced intraoperative pain compared with placebo. The 100-mg dose provided greater analgesic efficacy than the 50-mg dose.