Transversus abdominis plane (TAP) blocks for prevention of postoperative pain in women undergoing laparoscopic and robotic gynaecological surgery.

Rationale: Pain control following laparoscopic gynaecologic surgery is key to successful recovery. The efficacy of the transversus abdominis plane (TAP) block compared to no block or a local anaesthetic injection has not been well established in this population.

Objectives: To evaluate the benefits and harms of single-shot transversus abdominis plane blocks for the prevention of postoperative pain in women undergoing laparoscopic and robotic gynaecological surgery compared to no block, sham block, or injection of local anaesthetic.

Search methods: We searched CENTRAL, MEDLINE, Embase, two trials registers, and handsearched abstracts to 6 December 2024.

Eligibility criteria: We included prospective randomised controlled trials (RCTs) of adult women undergoing minimally invasive gynaecologic surgery that compared single-shot TAP block to no block, sham block, or injection of local anaesthetic. We excluded studies that were non-randomised or of non-gynaecologic surgery.

Outcomes: Critical and important outcomes: participant-reported pain intensity 24 hours following surgery (combined, at rest, and with movement), adverse events (serious adverse events, nausea and vomiting, postoperative sedation), opioid consumption 24 and 48 hours after surgery. Other outcomes: pain intensity 2, 6, 12, and 48 hours after surgery, opioid consumption intraoperatively, time from surgery to first participant requirement for postoperative opioid, time from surgery until discharge.

Risk of bias: We assessed the risk of bias with RoB 1.

Synthesis methods: We conducted meta-analyses using random-effects models. We calculated mean differences (MD) for continuous outcomes and risk ratios (RR) for dichotomous outcomes. We reported serious adverse events as described by the study authors. We summarised the certainty of evidence using GRADE methods.

Included studies: We included 21 RCTs with a total of 1645 participants. Studies were conducted in 10 countries, and published between 2011 and 2023. Six studies compared TAP block to no block, eight compared TAP block to an injection of local anaesthetic, and seven studies compared TAP block to sham block. Studies reported pain outcomes in various ways, so we made assumptions to allow us to combine data.

Synthesis of results: 1. TAP block compared to no block TAP blocks may result in little or no difference in pain 24 hours after surgery for women undergoing laparoscopic or robotic gynaecologic procedures (MD -4.66, 95% confidence interval (CI) -11.06 to 1.74; 4 RCTs, 242 women; I² = 88%; very low-certainty evidence). TAP blocks may result in little or no difference in pain at rest (MD -0.16, 95% CI -1.60 to 1.28; 2 RCTs, 146 women; I² = 0%, low-certainty evidence), or pain with movement (MD -1.59, 95% CI -4.44 to 1.25; 2 RCTs, 146 women; I² = 0%, low-certainty evidence) 24 hours after surgery. Two studies reported serious adverse events. None reported an event related to the TAP block (out of 50 women). TAP blocks may result in little or no difference in postoperative nausea and vomiting (RR 0.60, 95% CI 0.24 to 1.54; 2 RCTs, 111 women; I² = 0%, low-certainty evidence). TAP blocks may have little or no effect on 0- to 24-hour postoperative morphine consumption (MD 3.08, 95% CI -3.71 to 9.88; 3 RCTs, 140 women; I² = 70%; very low-certainty evidence). None of the studies reported 48-hour morphine consumption. 2. TAP block compared to local anaesthetic Women who received TAP blocks may experience a small reduction in 24-hour postoperative pain compared to local anaesthetic (MD -11.58, 95% CI -20.52 to -2.64; 6 RCTs, 393 women; I² = 89%; low-certainty evidence). None of the studies reported pain at rest or with movement. Four studies reported serious adverse events. None reported an event related to the TAP block (out of 168 women). TAP block may result in little or no difference in postoperative nausea and vomiting compared to local anaesthetic (RR 0.63, 95% CI 0.34 to 1.15; 1 RCT, 62 women; low-certainty evidence). There may be little or no difference in opioid consumption 0 to 24 hours after surgery for women who received a TAP block compared to local anaesthetic (MD -8.21, 95% CI -19.69 to 3.27; 2 RCTs, 177 women; I² = 81%; very low-certainty evidence). TAP block compared to local anaesthetic may result in little or no difference in opioid consumption 0 to 48 hours after surgery (MD -15.80, 95% CI -32.11 to 0.51; 1 RCT, 40 women; low-certainty evidence). 3. TAP block compared to sham block TAP block probably results in a small decrease in 24-hour postoperative pain compared to sham block (MD -14.26, 95% CI -27.03 to -1.48; 4 RCTs, 371 women; I² = 98%; moderate-certainty evidence). None of the studies reported pain at rest. TAP block probably results in a small reduction in pain with movement 24 hours following surgery (MD -3.60, 95% CI -6.72 to -0.48; 1 RCT, 60 women; moderate-certainty evidence). Six studies reported serious adverse events. None reported an event related to the TAP block (out of 307 women). There may be little or no difference in postoperative nausea and vomiting between TAP and sham blocks (RR 0.68, 95% CI 0.45 to 1.03; 3 RCTs, 244 women; I² = 0; low-certainty evidence). There may be little or no difference in 24-hour postoperative morphine consumption between TAP and sham blocks (MD -13.08, 95% CI -30.78 to 4.63; 5 RCTs, 310 women; I² = 99%; low-certainty evidence). None of the studies reported 48-hour postoperative opioid consumption.

Authors' conclusions: Amongst women undergoing minimally invasive gynaecologic surgery, we did not find a clinically meaningful effect of TAP block on postoperative pain or opioid consumption. However, there may be a small reduction of pain using TAP blocks compared to local anaesthetic or sham blocks. The TAP block is probably safe, since no adverse events were noted amongst the 525 women who received a block, and for whom safety data were available. The evidence is limited by heterogeneity in the results, risk of bias in the studies, and assumptions made for synthesis when combining data.

Funding: The review had no dedicated funding.

Registration: Protocol (2022): DOI: 10.1002/14651858.CD015145.