Local analgesia infiltration and abdominal nerve blocks during cesarean delivery may help provide postoperative pain relief, according to the results of a systematic review reported online in the July 8 issue of the Cochrane Database of Systematic Reviews.
"Childbirth is an emotion-filled event and the mother needs to bond with her newborn baby as early as possible," write Anthony A. Bamigboye, from University of Witwatersrand in Nelspruit, South Africa, and G. Justus Hofmeyr, from University of Fort Hare, Eastern Cape Department of Health in East London, South Africa. "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."
The goal of this review was to evaluate the impact of wound infiltration and/or irrigation with local anesthetic agent and abdominal nerve blocks on pain after cesarean delivery and on the mother's well-being and interaction with her infant.
The reviewers searched the Cochrane Pregnancy and Childbirth Group's Trials Register in April 2009 for randomized controlled trials of preemptive local analgesia during cesarean delivery. One review author extracted data from the 20 identified studies enrolling a total of 1150 women, and the second review author checked the extracted data.
Women who underwent cesarean delivery with regional analgesia followed by wound infiltration had decreased morphine consumption at 24 hours vs women who received placebo (standardized mean difference, –1.70 mg; 95% confidence interval [CI], –2.75 to –0.94).
In 1 study enrolling 100 women who had cesarean delivery under general anesthesia with wound infiltration and peritoneal spraying with a local anesthetic, the need for opioid rescue was decreased (risk ratio [RR], 0.51; 95% CI, 0.38 - 0.69), as was the numerical pain score (0 - 10) within the first hour (mean difference [MD], –1.46; 95% CI, –2.60 to –0.32).
Compared with women who had local anesthetic control, those with regional analgesia who had wound infiltration with a local anesthetic and a nonsteroidal anti-inflammatory cocktail required less morphine (1 study, 60 participants; MD, –7.40 mg; 95% CI –9.58 to –5.22).
In 4 studies enrolling a total of 175 women who had regional analgesia with abdominal nerve blockade, opioid consumption was reduced (MD, –25.80 mg; 95% CI, –50.39 to –5.37 mg). In a single study of 50 participants, the outcome of visual analog scale 0 to 10 during 24 hours was no better in those who had wound infiltration with a mixture of local analgesia and narcotics vs those who had local analgesia.
In women who had regional analgesia, adding ketamine to the local analgesia was not associated with any apparent benefit.
"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," the review authors write. "Nonsteroidal anti-inflammatory drugs as an adjuvant may confer additional pain relief."
Limitations of this review include those inherent in using opioid consumption as a method of pain assessment, testing at multiple times, and results mostly based on single trials with small sample size.
"A pharmacokinetic study of local anaesthetic absorption following wound and peritoneal infiltration is necessary," the review authors conclude. "Ultrasound guided direct block of anterior abdominal wall nerves in caesarean section should be explored. An important research agenda will also be the effect of the intervention on chronic pelvic pain."
Cochrane Database Syst Rev. Published online July 8, 2009.
