Study on Repeat Liposomal Bupivacaine for Post-Surgery Pain in Anal Fistula Patients.

At surgical closure, a single dose of undiluted liposomal bupivacaine (266 mg/20 mL) is administered without concurrent analgesics. The total 20 mL volume is divided into six equal aliquots (≈3.3 mL each) and infiltrated circumferentially around the incision using a 25-gauge or larger-bore needle. Injections target tissue layers above and below the fascia and within the subcutaneous plane, with frequent aspiration during administration to mitigate intravascular injection risk. Seventy-two hours postoperatively, a repeat dose of undiluted liposomal bupivacaine (266 mg/20 mL) is administered. Prior to infiltration, topical lidocaine cream is applied to the per-incisional skin for ≥20 minutes. The full 20 mL volume is then injected uniformly around the incision via circumferential needle advancement into pericicatricial tissues.