Surgical Transversus Abdominis Plane Block for Postoperative Analgesia in Lower Abdominal Surgeries: A Prospective Interventional Study

Introduction: Pain from lower abdominal surgeries originates from the abdominal wall incision. The Transversus Abdominis Plane (TAP) is a fascial plane between the internal oblique and the transversus abdominis muscle, which contains the nerve bundles. TAP block involves infiltrating this plane with anaesthetic drugs that block the somatic component of postoperative pain. Traditionally, the TAP block is given by anaesthesiologists as a blind procedure or under Ultrasound (US) guidance. In 2010, an innovative surgical TAP block method was developed, where the surgeon gives TAP block under direct vision before closing the abdomen during abdominal surgery. Many studies have recommended surgical TAP block as an intervention for achieving postoperative pain relief. Aim: To evaluate the efficacy of the surgical TAP block technique for postoperative analgesia following lower abdominal surgeries using Visual Analogue Scale (VAS) scores and by comparing the need for rescue analgesia and the total amount of analgesic drugs utilised within the first 24 hours of surgery. Materials and Methods: This hospital-based prospective interventional study was conducted in the Department of Obstetrics and Gynaecology at The Oxford Medical College Hospital and Research Centre, Bengaluru, Karnataka, India, from January 2022 to December 2022. The study participants included 108 women undergoing lower abdominal surgeries under spinal or epidural or combined regional anaesthesia and belonging to the American Society of Anaesthesiologists (ASA) physical status classification system ASA I or ASA II or ASA IIE. The study group included 54 women who received surgical TAP block with 20 mL 0.25% bupivacaine and 4 mg of dexamethasone, intraoperatively on either side before closure of the abdomen. Postoperative pain was assessed using VAS at regular intervals within 24 hours of surgery. VAS was also recorded whenever the participants demanded rescue analgesia. The control group included 54 women who received intravenous tramadol 50 mg eight hourly for postoperative pain relief, while the study group received rescue analgesia on demand or if the VAS score was recorded as three or more. The time for the first request for rescue analgesia and the total dose of rescue analgesic required in the first 24 hours after surgery were also recorded. Data were analysed using Statistical Package for Social Sciences (SPSS) version 25.0. For inferential statistics, numerical data were analysed by Chi-square test, and for continuous data, the Student's t-test was used. A p-value <0.05 was considered statistically significant. Results: The study group had significantly lower postoperative pain VAS scores when compared to the control group at four hours and beyond time intervals. The mean VAS scores at six hours were 1.85 in the study group and 2.35 in the control group (p-value=0.01), at 24 hours it was 2.04 in the study group and 2.24 in the control group (p-value=0.04). The mean time for the first rescue analgesia in the study group and control group was 11 hours 25 minutes and 2 hours 43 minutes, respectively, and the total tramadol consumption was 77.78 +/- 46.24 mg and 117.59 +/- 36.55 mg, respectively. Both results were statistically significant (p-value<0.001). Conclusion: Surgical TAP block significantly delays the need for rescue analgesia and decreases the total analgesia required in the first 24 hours after surgery. It is an effective, safe, and simple technique for achieving postoperative pain relief.