Intrathecal Morphine Versus Transverses Abdominis Plane Block for Caesarean Delivery

A Systematic Review and Meta-analysis

Tao-ran Yang; Xue-mei He; Xue-han Li; Ru-rong Wang


BMC Anesthesiol. 2021;21(174) 

In This Article

Abstract and Introduction


Background: The number of caesarean deliveries has been increasing. Although intrathecal morphine (ITM) can relieve pain and is widely applied in caesarean deliveries, it is associated with many side effects. Transversus abdominis plane block (TAPB), a new analgesic technology, has also began playing a certain role after caesarean delivery, with fewer adverse effects. This study mainly compares the analgesic and adverse effects of ITM and TAPB in caesarean delivery.

Methods: We systematically searched PubMed, Cochrane Library, EMBASE, and Web of Science, for randomised controlled trials (RCTs) published before 9 October, 2020 to compare the effects of ITM and TAPB. Primary outcome of the study was the pain score at rest 24 h after caesarean delivery, whereas the secondary outcomes were the pain score at movement 24 h after operation, postoperative nausea and vomiting (PONV), itching, and morphine consumption. For the outcome assessment, we conducted a sensitivity analysis.

Result: Six RCTs involving 563 patients and meeting the study inclusion criteria were included in this study. Results indicated no significant difference in the pain score between ITM and TAPB at 24 h of rest or movement. The sensitivity analysis results indicated that the resting pain score (95% CI = − 1.27 to − 0.28; P = 0.002) and 24-h moving pain score (95% CI = − 1.8 to − 0.07; P = 0.03) of the ITM group were lower than those of the TAPB group. The consumption of morphine in the ITM group was lower than in the TAPB group (95% CI = 1.92 to 4.87; P < 0.00001); however, in terms of adverse reactions, the incidence of pruritus (95% CI = 1.17 to 8.26; P = 0.02) and PONV (95% CI = 1.92 to 4.87, P < 0.00001) in the ITM group was higher than in the TAPB group.

Conclusion: Parturients in the ITM and TAPB groups exhibited similar analgesic effects. However, in the sensitivity analysis performed by eliminating the studies causing heterogeneity, the ITM group was found to have superior analgesic effects compared with the TAPB group, with less morphine consumption. Differently, the TAPB group displayed less side effects such as PONV. Therefore, TAPB is still a valuable analgesia option for patients who cannot use ITM for analgesia after caesarean delivery or those having a high risk of PONV.

Trial registration: Registration number: Registered on Prospero with the registration number of CRD42020210135.


The rate of caesarean delivery has been increasing annually because of social and psychological reasons.[1] Postoperative pain not only brings psychological torture to patients but also has a certain degree of impact on the recovery of patients after surgery and wound recovery.[2,3] For parturients after caesarean delivery, the lack of analgesia affects the maternal postpartum recovery, breast-feeding, and baby development on the hand, whereas on the other hand, it increases the risk of postpartum depression.[4,5] Approximately 500,000 women in Europe have been reported to experience acute postoperative pain annually.[3] Therefore, exploring effective analgesic methods for parturients after caesarean delivery is essential.

Intrathecal morphine (ITM) is considered the "gold standard" for providing analgesia after caesarean delivery. ITM can make hydrophilic morphine easily reach the cerebrospinal fluid and rapidly act on the central nervous system.[6] Therefore, the use of ITM can provide a superior analgesic effect after caesarean delivery compared with the systemic opioid analgesia technique.[7,8] Although ITM has obvious analgesic advantages, its side effects such as nausea, vomiting, itching, and even respiratory depression restrict its further application.[9,10]

With the rapid development of the ultrasound technology, the use of transversus abdominis plane block (TAPB) in regional anaesthesia is becoming increasingly popular. Local anesthetics are mainly injected between the superficial layer of transversus abdominis plane and deep layer of internal oblique muscle, thus blocking the anterior abdominal wall afferent nerve of T6-L1.[11] Recent studies have indicated that TAPB may play a vital role as an effective pain block of somatic surface pain induced by incision, which is much more obvious than the visceral pain caused by the traditional transverse incision.[12,13] According to the newest PROSPECT guideline, TAPB improve pain relief, increase patient satisfaction, and result in a reduction of rescue analgesia; the potential side effects of these regional analgesic techniques are also limited, and therefore, their use is recommended for providing analgesia to patients.[14]

Some meta-analyses on patient-controlled intravenous analgesia, quadratus lumborum block, and intrathecal morphine injection are available in literature. However, most of these studies have discussed the analgesic effect of a combination of TAPB and ITM. Some researchers believe that in case of postoperative analgesia with ITM, the addition of TAPB cannot further alleviate the pain. Only one meta-analysis compared the analgesic effect of TAPB and ITM after caesarean delivery.[15] Results of this meta-analysis indicated that ITM produces a superior analgesic effect compared with TAPB at rest 24 h after surgery; however, the evidence was not convincing since only two RCTs were included in the meta-analysis. In the present study, we aimed to synthesize the available data through updated systematic review and meta-analysis to assess, whether the analgesic effect and side effects of ITM differ from those of TAPB after caesarean delivery.