Local anaesthetic wound infiltration and abdominal nerves block during caesarean section for postoperative pain relief

Childbirth by caesarean section is becoming more frequent. Caesarean section requires an anaesthetic, either spinal, spinal epidural, epidural block or general anaesthesia. Postoperative pain is managed with a combination of an opioid such as morphine or pethidine and other analgesics. Opioids cause sedation and they can transfer to breast milk, also sedating the newborn infant. Childbirth is a deeply emotional experience and involves bonding with the newborn and starting breastfeeding. Improvements in pain relief that make the postanaesthesia period less uncomfortable are important. During the operation, local anaesthetic can be injected to block the nerves before cutting the skin or after closing the skin at the end of the operation (abdominal nerve block) or the wound can be irrigated or infiltrated with local anaesthetic solution to reduce postoperative pain (pre-emptive wound analgesia).

The authors identified twenty randomised controlled trials of sufficient quality involving 1150 women. These trials were carried out in both developed and developing countries. In general, local anaesthesia wound infiltration was of benefit in women having a caesarean section requiring regional anaesthetics because of a reduction in the use of opioid analgesia. Women undergoing general anaesthesia who had wound infiltration with local anaesthetics and peritoneal spraying required lower amounts of opioids in the first 24 hours post-operation compared to saline control. Those who had a general anaesthetic and the abdominal wall nerves blocked had reduced pain scores within the first 24 hours postoperative.

Women who had regional anaesthesia and abdominal nerves blocked also benefited by decrease in opioid requirements. Non-steroidal anti-inflammatory drugs provided additional pain relief but with more side effects of pruritus. The commonly used local anaesthetic agents do have side effects but these are very rare, ranging from allergy to cardiovascular and central nervous system effects. There was no report of side effects in infants following local anaesthetic infiltration but the number of women studied was small. The longer theatre time and cost of the local anaesthetic may be offset by less use of postoperative analgesia. The effect on the development of chronic pelvic pain should be an important area of research.

Authors' conclusions: 

Local analgesia infiltration and abdominal nerve blocks as adjuncts to regional analgesia and general anaesthesia are of benefit in caesarean section by reducing opioid consumption. Nonsteroidal anti-inflammatory drugs as an adjuvant may confer additional pain relief.

Read the full abstract...

Caesarean section delivery is becoming more frequent. Childbirth is an emotion-filled event and the mother needs to bond with her newborn baby as early as possible. Any intervention that leads to improvement in pain relief is worthy of investigation. Local anaesthetics, either on their own or in combination with opioids or nonsteroidal antiinflammatory drugs, have been employed as an adjunct to other postoperative pain relief strategies. Conflicting reports were noted.


To assess the effects of local anaesthetic agent wound infiltration/irrIgation and/or abdominal nerve blocks on post-caesarean section pain and the mother's well being and interaction with her baby.

Search strategy: 

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (April 2009).

Selection criteria: 

Randomised controlled trials of pre-emptive local analgesia during caesarean section.

Data collection and analysis: 

One author extracted data. The second author checked the data.

Main results: 

Twenty studies (1150 women) were included. Women who had caesarean section performed under regional analgesia and had wound infiltration had a decrease in morphine consumption at 24 hours (SMD -1.70mg; 95% confidence interval (CI) -2.75 to -0.94) compared to placebo.

In women under general anaesthesia, with caesarean section wound infiltration and peritoneal spraying with local anaesthetic (one study, 100 participants), the need for opioid rescue was reduced (risk ratio (RR) 0.51; 95% CI 0.38 to 0.69). The numerical pain score (0 to10) within the first hour was also reduced (mean difference (MD) -1.46; 95% CI -2.60 to -0.32).

Women with regional analgesia who had local anaesthetic and non-steriodal anti-inflammatory cocktail wound infiltration consumed less morphine (one study, 60 participants; MD -7.40 mg; 95% CI -9.58 to -5.22) compared to local anaesthetic control.

Women who had regional analgesia with abdominal nerves blocked had decreased opioid consumption (four studies, 175 participants; MD -25.80 mg; 95% CI -50.39 to -5.37).

For the outcome of visual analogue scale 0 to 10 over 24 hours, no advantage was demonstrated in the single study of 50 participants who had wound infiltrated with a mixture of local analgesia and narcotics versus local analgesia.

Addition of ketamine to the local analgesia in women who had regional analgesia does not confer any advantage.