Regional anaesthesia for labour, operative vaginal delivery and caesarean delivery: a narrative review

This narrative review discusses recent evidence surrounding the use of regional anaesthesia in the obstetric setting, including intrapartum techniques for labour and operative vaginal delivery, and caesarean delivery. Pudendal nerve blockade, ideally administered by an obstetrician, should be considered for operative vaginal delivery if neuraxial analgesia is contraindicated. Regional techniques are increasingly utilised in clinical practice for caesarean delivery to minimise opioid consumption, reduce pain, improve postpartum recovery and facilitate earlier discharge as part of enhanced recovery protocols. The evidence surrounding transversus abdominis plane and quadratus lumborum blockade supports their use when: long-acting neuraxial opioids cannot be administered due to contraindications; if emergency delivery necessitates general anaesthesia; or as a postoperative rescue technique. Current data suggest quadratus lumborum blockade is no more effective than transversus abdominis plane blockade after caesarean delivery. Transversus abdominis plane blockade, wound catheter insertion and single shot wound infiltration are all effective techniques for reducing postoperative opioid consumption, with transversus abdominis plane blockade favoured, followed by wound catheters and then wound infiltration. Ilio-inguinal and iliohypogastric, erector spinae plane and rectus sheath blockade all require further studies to determine their efficacy for caesarean delivery in the presence or absence of long-acting neuraxial opioids. Future studies are needed to: compare approaches for individual techniques; determine which combinations of techniques and dosing regimens result in optimal analgesic and recovery outcomes following delivery; and elucidate the populations that benefit most from regional anaesthesia in the obstetric setting. 이 비체계적 종설에서는 산과 환경에서의 부위 마취 사용과 관련된 최신 근거를 논의한다. 여기에는 분만, 수술적 질식 분 만 그리고 제왕절개를 위한 기법들이 포함된다. 수술적 질식 분만이 요구되나 신경축성(neuroaxial) 시술이 금기인 경우, 음부신경(pudendal nerve) 차단요법을 고려해야 하며 산과 전문의가 실시하는 것이 이상적이다. 아편유사제(opioid) 소비 를 최소화하고, 통증을 경감하며, 산후 회복을 개선하고, 조기 회복 프로그램(enhanced recovery after surgery)의 일부로 서 조기 퇴원을 촉진하기 위해 제왕절개 마취관리 시 부위 마 취 기법을 활용하는 사례가 점점 늘어나고 있다. 장기지속형 아편유사제의 신경축성 투여가 금기인 경우, 응급 분만으로 전신마취가 필요한 경우, 또는 수술 후 진통요법으로 사용하 기 위하여 복횡근면(transverse abdominis plane)이나 요방 형근(quadratus lumborum) 차단요법이 권장된다. 현재 데이 터에 따르면 요방형근 차단요법은 제왕절개 후 실시한 복횡근 면 차단요법보다 더 효과적이지 않다. 복횡근면 차단요법, 창 상(wound)에 카테터 삽입 및 일회 주사를 통한 상처 침윤은 모두 수술 후 아편유사제 소비를 줄이는 효과적인 기법이며, 이 중 복횡근면 차단요법이 가장 선호되고, 그 다음은 창상 카테터 삽입 그리고 침윤 순이다. 제왕절개 시 장기지속형 신 경축성 아편유사제를 투여 또는 투여하지 않은 경우에 따른 장골서혜(ilio-inguinal)신경 및 장골하복(iliohypogastric)신 경, 척추기립근면(erector spinae plane) 및 복직근집(rectus sheath) 차단요법의 효능에 대해서는 추가적인 연구가 필요 하다. 개별 기법에 대한 접근법을 비교하고, 어떤 기법과 용량 용법을 조합하는 것이 최적의 분만 후 진통 및 회복 결과로 이 어질 것인지 결정하며, 산과 환경에서 부위 마취가 가장 이익 이 되는 집단을 규명하기 위한 향후 연구가 필요하다. The global birth rate is 259 per minute [1], and the 2018 birth rate in the UK was 11 per 1000 people [2]. Data from NHS hospitals in England from 2018 to 2019 show that spontaneous vertex delivery is the most common mode of delivery (57%), followed by emergency caesarean delivery (17%), elective caesarean delivery (13%) and operative vaginal delivery (13%) [3]. Pain during labour and delivery is common: pain after caesarean delivery is a primary concern for women and postpartum pain constitutes an important domain of postpartum recovery following all modes of delivery [4]. Optimising postpartum analgesia is a key strategy of enhanced recovery protocols [5-8], as it improves recovery through facilitating earlier mobilisation, enhancing maternal-neonatal bonding and reducing hospital length of stay [9]. Multimodal analgesia regimens, including the use of neuraxial opioids, are widely regarded as the gold standard for women undergoing caesarean delivery [10]. Analgesic benefits of opioid medications must, however, be weighed against the potential for unwanted opioid-related side-effects such as nausea, vomiting, pruritus and sedation, that may worsen recovery and increase the requirement for pharmacological therapy [11]. However, multimodal analgesia may not always be suitable for all parturients due to contraindications, such as non-steroidal anti-inflammatory drugs in the setting of bleeding or renal impairment. In this population, the use of local anaesthetic techniques as adjuncts for preventing and treating peripartum pain are valuable [12, 13] and are considered safe in breastfeeding women [14]. The widespread availability and increased expertise in the use of ultrasound by anaesthetists means that the role of regional anaesthesia in the field of obstetric anaesthesia is expanding. Many of the recent reviews summarising the use of peripheral nerve and truncal plane nerve blockade have focused on anatomy, approaches for performing nerve blocks and advantages and disadvantages of specific nerve blocks used in the caesarean delivery setting [12, 13, 15]. In this narrative review, we provide a contemporary overview of the clinical applicability of regional nerve blocks for intrapartum analgesia to facilitate analgesia and recovery following caesarean delivery, which includes: transversus abdominis plane (TAP); quadratus lumborum (QLB); ilio-inguinal and iliohypogastric (ILIH); erector spinae plane (ESP) and rectus sheath blockade; and their combinations. Where possible, we focus on data from obstetric patients presented in published network and non-network meta-analyses, as well as randomised controlled trials. Intrapartum nerve blocks are compared with placebo, systemic opioids and neuraxial techniques where data are available. For blocks used for post-caesarean delivery analgesia, we summarise the available data for: nerve blocks performed in addition to long-acting neuraxial opioid; nerve blocks performed in the absence of long-acting neuraxial opioid; and nerve blocks compared with long-acting neuraxial opioid. For each comparison, we summarise the available data by focusing on the clinical outcomes of: opioid consumption; pain scores (up to 24 h); time to first analgesic use; quality of recovery scores; and incidence of adverse events. Nerve blocks performed during vaginal and operative vaginal delivery are usually administered by obstetricians rather than anaesthetists, and include paracervical and pudendal nerve blockade. Paracervical nerve blockade is less commonly utilised in modern obstetric practice due to the superior efficacy and safety of epidural analgesia and the potential for complications associated with paracervical blockade. Pudendal nerve blockade can be useful if the need for emergent delivery arises, if neuraxial anaesthesia is contraindicated or in the scenario of incomplete epidural analgesia due to, for example, sacral sparing. Paracervical nerve blockade involves injection of local anaesthetic submucosally into the fornix of the vagina lateral to the cervix, blocking the paracervical ganglion and providing analgesia to the cervix and uterus. It is effective for uterine contraction pain, but not for the sensory fibres of the perineum. It therefore does not provide analgesia for the second stage of labour. Complications and side-effects such as fetal bradycardia, local anaesthetic systemic toxicity, infection and postpartum neuropathy have been reported. A study of 198 women found that paracervical blocks using 2% lidocaine were more effective than placebo in relation to satisfaction with analgesia (RR 32.31, 95%CI 10.60–98.54) but at the expense of a higher incidence of fetal (transient fetal bradycardia) and maternal (giddiness, sweating and tingling in lower limbs) side-effects [16]. Two studies compared paracervical blockade with opioids for labour analgesia [17, 18]. Nikkola et al. performed a randomised study comparing intravenous fentanyl patient-controlled analgesia and paracervical blockade (10 ml bupivacaine 0.25%) for labour analgesia [17]. The study was terminated after recruiting only 12 women because one neonate in the fentanyl group experienced a significant decrease in peripheral oxygen saturations to 59% and required treatment with naloxone. This was attributed to the maternal opioid administered. Episodes of neonatal desaturation (SpO2 < 90%) were more frequent in the opioid group compared with the paracervical blockade group. Mean and maximum neonatal heart rates in addition to neonatal neurological and adaptive capacity scores were all lower in the opioid-treated group. Jensen et al. performed a randomised double-blind study comparing paracervical blockade (12 ml bupivacaine 0.25%) and intramuscular placebo vs. placebo paracervical blockade and 75 mg intramuscular pethidine [18]. Paracervical blockade was more effective than opioids for labour pain relief as assessed by a 100 mm VAS pain score (n = 109, RR 2.52, 95%CI 1.65–3.83) [18]. Satisfaction with analgesia was also greater in the paracervical group compared with the opioid group (n = 109, RR 2.52, 95%CI 1.65–3.83) [18]. However, time from pain relief to birth was faster in the opioid group (n = 117, RR 37.0, 95%CI 31.72–42.28) [18]. A Cochrane review by Novikova et al. aimed to establish the efficacy and safety of paracervical nerve blockade for labour analgesia by combining data from the above studies [19]. Paracervical blockade compared with opioid was not associated with an increased rate of operative vaginal delivery (n = 129, RR 1.02, 95%CI 0.56–1.87) or caesarean delivery (n = 129, RR 0.23, 95%CI 0.03–1.87) [17, 18]. None of the neonates had an Apgar score < 7 at 5 min (n = 122) [17, 18]. The number of women requiring additional intervention for pain relief did not differ between paracervical and opioid groups (n = 129, RR 1.73, 95%CI 0.54–5.50). There are limited data from randomised controlled trials reporting maternal-neonatal bonding, breastfeeding and long-term neonatal morbidity, and studies did not report the incidence of third- and fourth-degree perineal tears. Satisfaction with analgesia is higher, and pain scores are lower with paracervical blockade as compared with placebo or opioid analgesia. Paracervical blockade can therefore be considered to provide more effective analgesia than placebo and opioids for labour analgesia. To reduce the pain associated with the second stage of labour and for episiotomy repair, a pudendal nerve block can be administered. This targets the pudendal nerve trunk as it enters the lesser sciatic foramen about 1 cm inferior and medial to the attachment of the sacrospinous ligament to the ischial spine. The nerve can be accessed via the transvaginal (most commonly) and transcutaneous (or perineal) approaches (Fig. 1). Ultrasound-guided approaches administering local anaesthetic at the levels of the ischial spine and Alcock's canal have been described, but remain inadequately studied in the obstetric population [20]. Further studies are needed to compare the efficacy and safety of ultrasound vs. landmark-guided pudendal nerve blockade in obstetric patients [21]. The pudendal nerve is derived from S2–S4 and provides sensory innervation for the perineum, vulva and lower part of the vagina. This technique provides good analgesia for the second stage of labour and vaginal delivery, but does not relieve the pain of contractions during the first stage of labour. Reported complications include bleeding, infection and local anaesthetic systemic toxicity. Operative vaginal delivery may be indicated if the fetus fails to deliver spontaneously, when expedited delivery is necessary and complete cervical dilation has been achieved, or if pushing during the second stage of labour is undesirable, for example in the presence of a maternal cardiac lesion. Effective analgesia is required to facilitate delivery in these circumstances and enable the obstetrician to safely deliver the fetus. Traditionally, obstetricians have used pudendal nerve blockade to provide analgesia and facilitate operative vaginal delivery in the absence of epidural analgesia or if incomplete analgesia is provided with an epidural alone, for example if sacral sparing is evident. Pudendal nerve blockade is often ineffective, especially for mid-cavity or rotational deliveries. Pudendal nerve blockade is considered a safe and easily administered form of anaesthesia for operative vaginal delivery and repair of postpartum lacerations. Contemporary studies comparing peripheral nerve blockade with neuraxial techniques are limited. Hutchins et al. randomly allocated 183 women undergoing operative vaginal delivery to receive spinal anaesthesia or pudendal nerve blockade, with lidocaine administered in both groups [22]. Their study was unblinded and the method of randomisation sequence generation and allocation concealment was unclear, with selective reporting noted. No patient who received spinal anaesthesia experienced pain, 62% of patients undergoing rotational delivery under pudendal nerve blockade experienced severe pain and 15% had pain during non-rotatory forceps deliveries. Severe pain was less likely to be reported with the use of spinal anaesthesia (RR 0.02, 95%CI 0.00–0.27) compared with pudendal nerve blockade. All women receiving spinal anaesthesia reported effective analgesia compared with only 29% of women receiving pudendal nerve blockade (RR 3.36, 95%CI 2.46–4.60) [23]. Neither technique was associated with hypotension. A Cochrane review by Nikpoor et al. in 2013 aimed to assess the effectiveness and safety of different analgesic agents and methods available for operative vaginal delivery [23]. They concluded there was insufficient evidence from the four included randomised controlled trials, including a total of 388 women, to determine the most effective and safest analgesic agent or technique for women undergoing operative vaginal delivery. In addition to the above study by Hutchins et al., three studies compared diazepam with ketamine, vinydan-ether and either general or local anaesthesia [23]. Included trials had a high or unclear risk of bias and were of low quality. Each of the included trials was conducted prior to 1980, and assessed agents or methods not commonly used in modern clinical practice. The incidence of postnatal complications and neonatal morbidity secondary to pudendal nerve blockade has not been investigated adequately in randomised controlled trials or large prospective observational studies. Due to the implementation of epidural services on labour wards, there has been a decline in the use of techniques such as paracervical nerve blockade for labour and pudendal nerve blockade for operative vaginal delivery. The studies exploring these blocks tend to be small and of low quality, as assessed with the Cochrane risk of bias tool. Due to the lack of contemporary studies evaluating pudendal nerve blockade, it should only be considered for labour and delivery if contraindications to neuraxial techniques are present, or if there is no access to neuraxial analgesia. Pudendal nerve blockade is also an option for laceration repair if no epidural is in-situ or if the epidural is ineffective. Lumbar sympathetic blockade was compared with epidural analgesia in the first stage of labour in one randomised study involving 36 women [24]. Pain scores were higher 1 h following lumbar sympathetic block compared with epidural analgesia, but not significantly different at all other time-points up to 2 h following block placement [24]. Paravertebral blockade (Fig. 2) has been described in several small studies and in case series as a method of providing analgesia during the first stage of labour [25, 26]. Posterior QLB (described later under peripheral nerve blocks for caesarean delivery) for analgesia in the first stage of labour has also been described with good effect in a patient with haemophilia [27]. Erector spinae plane blockade (Fig. 2) could theoretically be used to provide analgesia for labour and delivery, however, there are no published reports describing their use in these settings. The sites of local anaesthetic agent deposition for TAP, QLB, ILIH, ESP and rectus sheath blockade are depicted in Figures 2 and 3. In the caesarean delivery population, TAP blockade is the most studied truncal nerve block. The surface anatomy landmark technique has been superseded by ultrasound-guided (anterior subcostal, lateral and posterior) approaches. Ultrasound-guided TAP blockade facilitates accuracy of needle placement [28]. Few studies have compared these approaches in the obstetric setting, however, one study suggests the posterior approach is associated with reduced opioid consumption up to 36 h and reduced pain scores up to 24 h following caesarean delivery [29]. Meta-analysis sub-group analyses found that a more posterior injection site may produce superior and more prolonged analgesia compared with lateral TAP blockade [30]. When performed by a surgeon under direct view of intra-abdominal structures during caesarean delivery, the block takes significantly less time to perform and provides similar analgesia as compared with an anaesthetist-administered block [31]. Table 1 summarises the four meta-analyses to date, which report the use of TAP blockade in the caesarean delivery setting [32-35]. A systematic review by Fusco et al. [36] included four studies not reviewed in meta-analyses by Mishriky et al. and Abdallah et al. [32, 33]. Based on findings from the 20 published randomised controlled trials included in three meta-analyses, TAP blockade compared with placebo/inactive controls (in the absence of long-acting neuraxial opioid) was associated with a 20–24 mg decrease in 24-h morphine consumption following caesarean delivery [32-34]. No difference in opioid consumption was, however, demonstrable when TAP blockade with a long-acting neuraxial opioid was compared with a long-acting neuraxial opioid in the absence of TAP blockade. In the absence of long-acting neuraxial opioids, TAP blockade was associated with 6-h pain scores at rest which were consistently lower than placebo TAP blockade [33, 34]. In the largest meta-analysis to date, 24-h pain scores on movement were lower in the TAP group (without long-acting neuraxial opioids) [34], but 24-h pain scores at rest were not different. In the presence of a long-acting neuraxial opioid, 6-h pain scores on movement were lower in the TAP blockade group [33, 34], however, no differences in 24-h pain scores were demonstrable. Finally, TAP blockade compared with long-acting neuraxial opioids resulted in higher 6- and 24-h pain scores at rest and on movement. In the absence of long-acting neuraxial opioids, time to analgesia request was prolonged on average by 2.4 h with TAP blockade compared with placebo. None of the included studies evaluated global recovery using a validated scale. Because of the limited duration of TAP blockade in the setting of long-acting opioids and multimodal analgesia, it may currently be better suited as a rescue technique (for severe breakthrough postpartum pain or women requiring escalating doses of opioids to control their pain), rather than as a routine block offered to all patients. A case series of TAP blockade for severe incisional pain after resolution of spinal block following caesarean delivery demonstrates this potential indication [37]. It was found to provide excellent pain relief for 10–19 h, and mitigated further opioid requirement. Case reports have also described successful TAP blockade after caesarean delivery for intractable incisional neuropathic pain [38], and pain from an abdominal wall hematoma [39]. One randomised controlled trial compared TAP blockade efficacy with and without the addition of clonidine in 90 women [40]. There were no differences in wound hyperalgesia, pain scores, opioid requirement and chronic pain descriptors up to 1 year following surgery. The use of such adjuncts to improve block efficacy, however, remains underexplored. Future studies should focus on the use of adjuncts in targeted populations, such as women who experience chronic pain prior to surgery. A case series utilised TAP catheters in five women after caesarean delivery for 41–70 h and found it extended time to first opioid request and reduced pain scores [41]. However, there are no randomised controlled studies that have evaluated TAP catheters following caesarean delivery. This may be due to logistical issues related to providing this service (equipment, expertise, additional time to perform block, and risk of secondary block failure) and maternal preference (inconvenience of extra equipment and impaired ability to clean and bathe). Another concern is the risk of local anaesthetic systemic toxicity associated with TAP blockade, which has been reported in several published studies in the obstetric population [42, 43]. Two randomised controlled studies have reported tonic-clonic seizures in two patients following administration of ultrasound-guided TAP blockade, which were attributed to local anaesthetic toxicity [44, 45]. The woman in a study by Chandon et al. received 150 mg levobupivacaine and developed convulsions minutes later, requiring transient mechanical ventilation and successful treatment with intravenous lipid emulsion infusion [44]. The study was terminated early due to this adverse event. Jadon et al. reported one woman receiving 150 mg ropivacaine [45], who developed convulsions 20 min later. She was treated conservatively with 2 mg intravenous midazolam and 24 h of close monitoring, during which time no untoward events were noted. There are also other reports of local anaesthetic systemic toxicity following TAP blockade in non-randomised controlled studies within the obstetric setting [42, 46]. Fortunately, none of these patients had significant long-term morbidity. Physiological changes of pregnancy may increase the risk of local anaesthetic toxicity [47], and local anaesthetic given at recommended doses can produce peak plasma concentrations in pregnant women that often exceed threshold levels associated with toxicity [48, 49]. A meta-analysis by Ng et al., using data from 14 randomised controlled studies, reported no difference in analgesia outcomes (including opioid consumption, pain scores up to 24 h and time to first analgesia request) between low-dose and high-dose (≤ 50 mg vs. > 50 mg bupivacaine equivalents per side) TAP blocks [35]. As local anaesthetic toxicity may even occur within the recommended maximal allowable local anaesthetic doses, results from this meta-analysis suggest that clinicians should utilise ≤ 50 mg bupivacaine equivalents per side when performing TAP blocks in the obstetric setting to minimise the risk for local anaesthetic systemic toxicity. Nedeljkovic et al. randomly allocated 186 women undergoing elective caesarean delivery in a prospective multicentre, randomised, double-blind controlled trial [50]. Women received spinal anaesthesia with long-acting neuraxial opioid, in addition to TAP blockade with long-acting liposomal bupivacaine (266 mg) and bupivacaine hydrochloride (50 mg), or bupivacaine hydrochloride (50 mg) alone. Decreased 72-h morphine consumption was reported in the liposomal bupivacaine group (-16.5 mg, 95%CI -30.8 to -2.2 mg, p = 0.012). The area under the curve of imputed pain intensity scores through 72 h supported non-inferiority of long-acting liposomal bupivacaine plus bupivacaine hydrochloride vs. bupivacaine hydrochloride alone. The incidence of serious adverse events was not different between groups (3% in each group). These results suggest there may be an opioid-reducing benefit of adding long-acting liposomal bupivacaine to bupivacaine TAP blocks after caesarean delivery. This is the most studied truncal nerve block for caesarean delivery since 2015, and there are 18 ongoing studies in this area. A meta-analysis by Xu et al. included 12 randomised controlled studies of QLB after caesarean delivery with and without long-acting neuraxial opioids (Table 1) [51]. The included studies utilised various approaches (two lateral, eight posterior and two anterior) of the QLB. Pooled results from six randomised controlled studies showed a reduction in 24-h opioid consumption with QLB (-14.1 mg 95%CI -20.8 to -7.5, p < 0.001) in the absence of long-acting neuraxial opioids. Pooled data from six studies also showed a significant reduction in 48-h opioid consumption with QLB in the absence of long-acting neuraxial opioids (-20.8 mg, 95%CI -33.1 to -8.51, p < 0.001). Resting pain scores (0–10) were significantly lower at 12 h (1.20 95%CI -1.66 to -0.73, p < 0.001) but not at 24 or 48 h with QLB. Pain scores on movement were lower at 12 and 48 h with QLB, but not at 24 h. There was no difference in time to ambulation between groups. Sub-group analysis of different QLB approaches was not possible due to the lack of studies utilising the lateral and anterior approaches. One included study in the meta-analysis by Xu et al. reported that QLB with long-acting neuraxial opioids was no more effective than with long-acting neuraxial opioid alone [52]. However, Irwin et al. subsequently published a study which found that adding QLB to long-acting neuraxial opioids does not reduce opioid consumption or provide an additional analgesic benefit beyond 6 h postoperatively [53]. A randomised controlled trial by Kang et al., also not included in the meta-analysis by Xu et al., reported lower VAS pain scores in patients receiving anterior vs. posterior QLB without neuraxial long-acting opioids (24.6 vs. 36.1, respectively, on a 0–100 scale). However, no significant differences were detected in 48-h opioid consumption between groups. It should be noted that epidural morphine provided optimal analgesia (lowest pain scores and opioid consumption) in this study [54]. Isolated ilio-inguinal nerve blocks have been superseded by combined ILIH blockade, without significantly increasing time taken to perform the procedure or adding to the level of difficulty. Three small randomised controlled studies involving between 34 and 59 patients have been conducted in the USA using landmark [55, 56] and ultrasound-guided [57] ILIH as part of a multimodal analgesia regimen compared with placebo. Two of these studies administered long-acting neuraxial opioid [56, 57]. One study reported reduced 24-h morphine consumption (67 mg vs. 48 mg) associated with ILIH blockade in the absence of long-acting neuraxial opioid [55]; another study reported no difference in postoperative morphine consumption with long-acting neuraxial opioid [57]; and no patients required rescue morphine in the remaining study [56]. Pain scores were lower in the ILIH group at 12 h (20 vs. 10 out of 100) in one study with long-acting neuraxial opioid [56], but not different at any time-points up to 24 and 48 h following caesarean delivery in the two other studies [55, 57]. Time to first analgesia was reduced with ILIH in the presence of long-acting neuraxial opioid in a study by Wolfson et al. (14.3 vs. 5.6 h) [56], but this was not assessed in the remaining two studies [55, 57]. A study by Bunting et al. assessed single-injection ILIH blockade in patients receiving general anaesthesia and reported a reduction in pain scores and requirement for rescue analgesia [58]. However, Huffnagle et al. observed no difference in either incisional or overall surgical pain using a similar ILIH block technique following spinal anaesthesia [59]. Bell et al. also studied women receiving spinal anaesthesia, but used a multi-injection ILIH block technique instead [55]. The authors found that women receiving ILIH blocks required less morphine postoperatively but demonstrated no differences in pain or opioid-related side-effects, such as nausea and pruritus. Ganta et al. studied wound infiltration combined with ILIH block following caesarean delivery, and reported a reduction in postoperative pain scores and analgesic requirements with the combined technique, as compared with no local anaesthetic [60]. Finally, the potential benefits of using continuous ILIH blocks for caesarean delivery analgesia were reported in a small case series [61]. Bilateral catheters were sited under ultrasound guidance and 0.2% ropivacaine was infused at 4 ml.h−1 for 72 h. Patients had minimal pain and analgesic requirements despite receiving no long-acting neuraxial opioids. Further studies and meta-analyses are needed to help determine the efficacy of ILIH blockade and catheters in the presence and absence of long-acting neuraxial opioid with concomitant use of multimodal analgesia regimens. Data reporting the use of ESP blockade in the caesarean delivery setting are limited to case reports and a single randomised controlled study by Hamed et al. [62]. Bilateral ultrasound-guided ESP blocks were performed at the level of T9 and compared with long-acting neuraxial opioid (100 μg intrathecal morphine) in 140 women. During the first 8 h, resting VAS (0–10) pain scores were, on average, 0.31 higher in the neuraxial opioid group (0.31, 95%CI 0.08–0.54, p = 0.008). Between 0 and 24 h postoperatively, resting VAS pain scores were, on average 0.25 units higher in the neuraxial opioid group (0.25, 95%CI 0.07–0.43, p = 0.008). Opioid consumption was also decreased and time to first analgesia was increased with ESP blockade compared with long-acting neuraxial opioid. While this technique shows promise based on results from this well-designed study, further adequately powered studies are needed to corroborate these findings before this technique can be recommended for routine use. Furthermore, comparisons to other blocks in the presence and absence of neuraxial opioid are needed to inform the future role of this technique. In 131 women undergoing elective caesarean delivery, a randomised controlled trial reported the use of rectus sheath blockade as compared with a placebo block performed by a surgeon under direct vision with and without long-acting neuraxial opioid [63]. A greater number of analgesia doses in 48 h were required in patients receiving rectus sheath blocks without intrathecal morphine, compared with patients receiving intrathecal morphine, with or without rectus sheath blockade. Rectus sheath blockade without intrathecal morphine was associated with a higher area under the curve as compared with rectus sheath blockade with long-acting neuraxial opioid and long-acting neuraxial opioid alone. Further studies are needed to evaluate the efficacy of ultrasound-guided rectus sheath blocks and to corroborate results from this single study. There has been one randomised controlled trial comparing combined QLB approaches in the caesarean delivery population by Kang et al. The authors reported lower pain scores at rest and on movement up to 48 h with QLB combined posterior and anterior approaches compared with separate approaches [54]. The 48-h morphine consumption in the combined group was 2.7 mg, compared with 6.1 mg and 5.7 mg in the posterior and anterior approaches separately. It should be noted that the epidural group, which received a bolus of 9 mg ropivacaine (0.15%) and 2 mg morphine at the end of surgery, had the lowest morphine consumption amongst all groups (1.3 mg). A triple-blind placebo controlled randomised trial by Staker et al. is one of few studies to combine different peripheral nerve block techniques in the caesarean delivery setting [64]. In this study, ilio-inguinal and TAP blocks (i-TAP) were compared with long-acting neuraxial opioid alone as part of a multimodal analgesia strategy. Twenty-four hours of opioid consumption via intravenous fentanyl patient-controlled analgesia was significantly lower in the i-TAP group (72 mcg vs. 179 mcg, p < 0.001). Pain VAS (0–10) scores at rest (1.9 vs. 5, p = 0.006) and on movement (4.7 vs. 11.3, p = 0.001) across all time-points over 24 h were also significantly lower in the i-TAP group. This combined technique shows promise, but further studies are needed to corroborate these findings and to also determine which patient populations are likely to benefit most from this technique, such as patients at risk for developing chronic pain or persistent opioid use. Few studies have compared the nerve blocks described in this review. A study by Guo et al. compared posterior QLB with ILIH blockade in the absence of long-acting neuraxial opioid (n = 90). No significant differences were reported between techniques for the outcome of postoperative opioid consumption. However 12- and 24-h pain scores were lower in the QLB compared with ILIH group [65]. Most studies have compared individual nerve blocks with placebo blocks, sham blocks or no blocks. Network meta-analysis allows for simultaneous comparison and ranking of multiple treatment arms for efficacy and side-effects. Using direct and indirect comparisons can increase the precision of effect size estimates, yielding important information to clinicians [66]. A recent network meta-analysis including 42 studies (n = 2906) compared the use of TAP blockade with wound infiltration and wound catheters for analgesia, in the absence of long-acting intrathecal opioid following caesarean delivery [67]. For the primary outcome of 24-h opioid consumption, all three techniques were effective at reducing opioid consumption with ranking favouring TAP blockade followed by wound catheters and wound infiltration. Transverse abdominis plane blockade was more efficacious than wound infiltration for 12-h numerical pain scores at rest (standardised mean difference 0.93). Both wound catheters (standardised mean difference 0.93) and TAP blockade (standardised mean difference 0.72) were associated with lower 12-h numerical reporting scale pain scores on movement compared with wound infiltration. These effect sizes are likely to signify clinical significance between techniques. Transverse abdominis plane blockade ranked highest for 12- and 24-h resting pain scores whereas wound catheters and wound infiltration ranked highest for 12- and 24-h pain scores on movement respectively. Transverse abdominis plane blockade was the best ranking technique for the outcome of ‘time until first analgesia’. Data directly comparing QLB with TAP blockade in the caesarean delivery setting are limited to two randomised controlled studies [68, 69]. A network meta-analysis by El-Boghdadly et al. aimed to determine which technique provided superior analgesia following caesarean delivery in the absence of long-acting neuraxial opioid, with 24-h opioid consumption as the primary outcome measure [70]. Data from 31 included studies (n = 2188) demonstrated that while both TAP and QLB were more effective than control groups, there was no difference between these techniques for any of the outcomes assessed (opioid consumption, pain scores, time until first analgesia and side-effects). There was minimal analgesic benefit in adding either technique to long-acting neuraxial opioid. Therefore, TAP blockade is not superior to QLB for caesarean delivery analgesia in the absence of long-acting neuraxial opioid. Only one included study reported quality of recovery using a global recovery score (Obstetric Quality of Recovery-11 [71]), for which there was no difference between QLB and the control group [53]. Future studies should focus on comparing techniques and approaches of individual peripheral nerve or truncal blocks in addition to evaluating analgesic and global recovery outcomes beyond 24 h [72]. The impact of regional blocks on recovery domains such as mobility, breastfeeding and maternal-neonatal bonding [4] are important to consider when evaluating analgesia options. Finally, future studies should interrogate the use of regional nerve blockade in targeted groups of patients that have an increased likelihood of benefiting from these interventions, such as: patients who have reported severe pain following previous surgery; women who experience severe side-effects with long-acting neuraxial opioids; women who are opioid-dependent prior to planned caesarean delivery; and women who experience chronic pain prior to hospital admission. The role of regional blocks as a rescue analgesia technique in women experiencing severe pain despite standard analgesics or needing escalating does of opioids also requires further study. This study was funded by Stanford University School of Medicine. No other external funding or competing interests declared.