Adequate pain relief following caesarean section is particularly important, because the mother needs to be sufficiently comfortable to care for her baby. She is also at increased risk of thromboembolism, and effective analgesia enables early mobilisation and facilitates bonding of the mother with the infant. Poorly controlled pain may be a risk factor for the development of chronic pain and may result in adverse psychological sequelae in the mother.
It is also important to remember that women having other procedures (e.g. repair of perineal tears) may be in considerable discomfort or pain afterwards.
Problems and special considerations
Psychological considerations are important. The mother who has been delivered by elective caesarean section under regional anaesthesia, with preoperative preparation and discussion about postoperative analgesia, cannot be directly compared with the mother who has been delivered by emergency caesarean section under general anaesthesia after many hours of labour and a failed trial of forceps delivery. (In the worst scenario she may also have received an episiotomy.)
Most published studies of post-caesarean analgesia are, for logistical reasons, performed in women having elective caesarean section, and the results should therefore be interpreted cautiously.
The ideal analgesic should of course be extremely effective, universally applicable, cheap to use and free from unwanted side effects, which include the risk of adverse outcomes in breastfed neonates (see Chapter 162, Drugs and breastfeeding). The ideal analgesic does not exist, and the demand for freedom from unwanted effects is particularly important in obstetric patients.
It is important to remember that unwanted effects include the need for intravenous cannulae and infusions, urinary catheters and additional monitoring equipment. Safety is vital in a patient population that is young and fit with newly born dependants. Other side effects that may be acceptable to an elderly general surgical population (e.g. pruritus, nausea and sedation) are unacceptable to women wishing to care for babies.
The use of various opioids by the subarachnoid or epidural routes has become routine, but the level of nursing care required by women who have received this method of analgesia remains controversial. The relative risk and timing of respiratory depression associated with different opioids variy, but none can be considered completely safe in this respect. Equally, all centrally administered opioids cause nausea, vomiting and pruritus, although to differing degrees. Although there can be no doubt that high-dependency care, either in a high-dependency unit or given in a normal postnatal ward by one-to-one or one-to-two patient supervision, is ideal, many obstetric units are unable to provide this. Protagonists of spinal opioids point out that all opioids, given by any route, have the capacity to cause respiratory depression, and that no special precautions are taken after the administration of intramuscular opioids. Various compromises are made at a local level.
Women undergoing non-caesarean procedures can experience considerable postoperative pain (e.g. perineal) but may find that this is not always appreciated by the medical and midwifery staff, who may focus on mothers who had caesarean section.
Management options
A combination of paracetamol, non-steroidal anti-inflammatory drugs (NSAIDs) and opioids is used in the majority of women to provide analgesia following caesarean section. Analgesics prescribed regularly are more likely to be given than those prescribed ‘as required’, but midwives should be educated about the assessment and management of postoperative pain and encouraged to give analgesics as prescribed. Published research, including a recent Cochrane review, has failed to demonstrate clearly the superiority of any one route or of any one drug or drug combination for post-caesarean analgesia.
Caesarean section under general anaesthesia
The most commonly used drugs in this situation are intraoperative intravenous opioids (e.g. morphine 10-20 mg or diamorphine 5-10 mg), an NSAID and either oral or patient- controlled intravenous opioids postoperatively. Regular paracetamol and NSAIDs act synergistically with both strong and weak opioids. NSAIDs have an opioid-sparing effect and may also have a role in the management of the visceral component of pain after caesarean section. Nevertheless, their potentially adverse effects on renal function should be considered in women who are hypovolaemic and in those who have compromised renal function. Similarly, they are contraindicated in women with severe pre-eclampsia because of their effect on platelet function and renal function, and should also be used with caution in women with asthma.
Some studies have suggested a role for adjuvant drugs such as gabapentin or ketamine in women who have risk factors for chronic pain or in those with severe postoperative pain that is difficult to control. The paucity of data on the effectiveness and side-effect profile of these agents in the mother and newborn may, however, limit their usage.
Bilateral ilioinguinal blocks have been shown to improve postoperative pain control, and should be considered for all cases under general anaesthesia. Rectus sheath blocks may also be used, although they are more difficult immediately after caesarean section than in elective gynaecological surgery. Increasingly popular are transversus abdominis plane (TAP) blocks, which may be performed under ultrasound guidance at the end of the surgery. Although TAP blocks have been described as easy to perform, the efficacy of the block is variable and very operator-dependent, and there have been case reports of bowel injury, as well as intraperitoneal and intravascular injection of local anaesthetic. In addition, a systematic review and meta-analysis has concluded that a clinically significant opioid-sparing effect of TAP blocks was demonstrable in parturients who have not received intrathecal morphine for caesarean delivery, but not in those who had.
Other local anaesthetic techniques such as single or continuous wound infiltration have also been described.
In the emergency situation there may be an epidural catheter in place but insufficient time to extend a block for anaesthesia, but this does not preclude use of the catheter for postoperative analgesia using epidural opioids.
Caesarean section under regional anaesthesia
There is common anecdotal evidence that women experience less pain following caesarean section under regional anaesthesia than under general anaesthesia, although this is difficult to substantiate. The pre-emptive action of epidural or spinal anaesthesia remains unproven. Subarachnoid fentanyl (10-20 mg) is used to improve the quality of intraoperative anaesthesia, but its action does not extend significantly into the postoperative period. This has led to the global use of subarachnoid fentanyl and morphine (0.1-0.2 mg), which provides very effective analgesia for up to 24 hours, but is considered by some anaesthetists to be associated with the highest risks of nausea, vomiting, pruritus and respiratory depression. In the UK, subarachnoid diamorphine (200-400 µg) is commonly used, providing analgesia both during surgery and extending 6-8 hours postoperatively.
Epidural or combined spinal-epidural anaesthesia allows greater flexibility for postoperative analgesia. Epidural local anaesthetic alone is unsuitable, since women are unable to mobilise and dislike the sensation of being numb. Fentanyl (e.g. 50-100 µg) is relatively short-acting (3-4 hours) but is reported to have the lowest incidence of side effects; morphine (e.g. 2-4 mg) has delayed onset of action but long duration (18-24 hours) and a higher incidence of side effects, including delayed respiratory depression. Diamorphine (e.g. 2-3 mg) is available in the UK although in few other countries in the world and has an intermediate duration of action and incidence of side effects. Sufentanil is widely used in North America and Europe but is not available in the UK.
Patient-controlled administration of epidural opioids (e.g. fentanyl or pethidine) has been described, but this is uncommon in the UK.
Regardless of choice of opioid, analgesia is improved by the addition of an NSAID (subject to the same precautions outlined above) and by the regular administration of simple analgesics such as paracetamol.
Other procedures
Women having perineal repairs and other procedures should be told that adequate analgesia will be made available should they need it, and the staff looking after them should be encouraged to take their pain seriously. A recent Cochrane review has suggested a beneficial effect of NSAIDs in the control of acute postpartum pain in non-breastfeeding women who have sustained perineal trauma. Neuraxial opioids and regular analgesics may be required, and it may be easiest and kindest to prescribe the same postoperative analgesics as for caesarean section.
Key points
• The mother needs to be alert and comfortable in order to feed, care for and bond with her baby.
• Paracetamol, opioids and non-steroidal anti-inflammatory drugs are the mainstay of postoperative analgesia.
• Opioids, whatever the route of administration, are associated with respiratory depression, nausea and vomiting.
• Opioids administered by the epidural and subarachnoid routes are also associated with pruritus and possible delayed respiratory depression.
Further reading
Abdallah FW, Halpern SH, Margarido CB. Transversus abdominis plane block for postoperative analgesia after caesarean delivery performed under spinal anaesthesia? A systematic review and meta-analysis. Br J Anaes 2012; 109: 679-87.
Carvalho B, Butwick AJ. Postcesarean delivery analgesia. Best Pract Res Clin Anaesthesiol 2017; 31: 69-79.
Mkontwana N, Novikova N. Oral analgesia for relieving post-caesarean pain. Cochrane Database Syst Rev 2015; (3): CD010450.
Wuytack F, Smith V, Cleary BJ. Oral non-steroidal anti-inflammatory drugs (single dose) for perineal pain in the early postpartum period. Cochrane Database Syst Rev 2016; (7): CD011352.