Laparoscopically guided transversus abdominis plane block versus local wound analgesia in laparoscopic surgery for peritoneal endometriosis: study protocol for a prospective randomized controlled double-blinded LTAP-trial

BACKGROUND: Ultrasound-guided transversus abdominis plane block (TAP) performed by anesthesiologist has been shown to be an effective and safe analgesia method in abdominal surgery, reducing postoperative opioid consumption. Recently, there has been growing interest to insert TAP under laparoscopic vision (LTAP) by surgeon. LTAP has been used in laparoscopic gastrointestinal surgery, but studies on LTAP in gynecologic laparoscopic surgery are sparse and inconsistent. The purpose of this study is to compare the efficacy of LTAP and local wound analgesia in laparoscopic surgery due to suspected or diagnosed superficial peritoneal endometriosis. METHODS: The LTAP-trial is a prospective randomized controlled double-blinded study comparing the efficacy and safety of LTAP with local wound analgesia in laparoscopic endometriosis surgery. Patients are randomized to receive LTAP with levobupivacaine and wound infiltration with placebo or wound infiltration with levobupivacaine and LTAP with placebo. The primary outcome is postoperative opioid consumption measured by patient-controlled analgesia (PCA) pump. Secondly, subjective postoperative pain up to 24 h postoperatively will be measured by Numeric Rating Scale (NRS). Additional outcome measures are factors related to recovery and length of stay in the hospital as well as a 6-month follow-up survey regarding pain (NRS) and endometriosis-related wellbeing (endometriosis-related health profile, EHP-30) after surgery. A total of 46 patients will be randomized in a proportion of 1:1. DISCUSSION: Patients with peritoneal endometriosis are often prone to severe postoperative pain that may prohibit their enhanced recovery after laparoscopy. Thus, there is a need for effective postoperative pain management with minimal side-effects. This study focusing on laparoscopically inserted transversus abdominis plane block may provide new insight in dealing with postoperative pain after laparoscopic endometriosis surgery as well as after other gynecologic surgery. TRIAL REGISTRATION: The LTAP-trial -protocol has been prospectively registered to ClinicalTrials.gov, ID: NCT04735770. Registered on February 2021.