Local anaesthetic wound infiltration used for caesarean section pain relief: a meta-analysis

Local anaesthetic wound infiltration techniques were reported to reduce opiate requirements and pain scores in women undergoing caesarean section (CS). However, the results were conflicting. The primary aim of this meta-analysis was to assess whether local analgesia could reduce pain intensity when injected via wound catheters.

A search of randomized clinical trials (RCTs) evaluating local analgesia in caesarean surgery in PubMed, EMBASE and the Cochrane database was performed. Cumulative morphine consumption and pain scores at rest at different time point after surgery were extracted and synthesized using random or fixed model for meta-analysis. Subgroup analysis was performed according to incision type and administration regimen.

Nine RCTs with a total of 512 patients were included. Cumulative morphine consumption was lower in LA group compared with placebo group in the first 12 h (SMD = -0.736, 95% CI (-1.105, -0.368)), 24 h (SMD = -0.378, 95% CI (-0.624, -0.132)) and 48 h after surgery (SMD = -0.913, 95% CI (-1.683 to -0.143)). Lower morphine consumption was observed in the first 6 h after surgery but the reduction failed to meet the common level of significance. Pain scores was significantly reducedat 12 h but not 6 h after surgery in the LA group compared with placebo group. At 24 h and 48 h after surgery, the pain sore was lower but the difference did not meet the common level of significance. Lower rate of post-operative nausea was observed in the LA group.

Local anaesthetic wound infiltration can reduce morphine requirements and the rate of patients suffer nausea but not pain scores after caesarean section. Further procedure-specific RCTs were encouraged to confirm the efficacy of local anaesthetic wound infiltration techniques.