Abstract: We included eight studies involving 353 children in the review. These studies reported different types of interventions (lignocaine or bupivacaine), observation times, and forms of measuring and describing the outcomes, making it difficult to conduct meta-analyses. In the comparison of infraorbital nerve block versus placebo, there was a large effect in mean postoperative pain scores (our first primary outcome) favouring the intervention group (standardised mean difference (SMD) -3.54, 95% confidence interval (CI) -6.13 to -0.95; very low-quality evidence; 3 studies; 120 children). Only one study reported the duration of analgesia (in hours) (second primary outcome) with a difference favouring the intervention group (mean difference (MD) 8.26 hours, 95% CI 5.41 to 11.11; very low-quality evidence) and less supplemental analgesic requirements in the intervention group (risk ratio (RR) 0.05, 95% CI 0.01 to 0.18; low-quality evidence). In the comparison of infraorbital nerve block versus intravenous analgesia, there was a difference favouring the intervention group in mean postoperative pain scores (SMD -1.50, 95% CI -2.40 to -0.60; very low-quality evidence; 2 studies; 107 children) and in the time to feeding (MD -9.45 minutes, 95% CI -17.37 to -1.53; moderate-quality evidence; 2 studies; 128 children). No significant adverse events (third primary outcome) were associated with the intervention, although three studies did not report this outcome. Five out of eight studies found no unwanted side effects after the nerve blocks. Overall, the included studies were at low or unclear risk of bias. The reasons for downgrading the quality of the evidence using GRADE related to the lack of information about randomisation methods and allocation concealment in the studies, very small sample sizes, and heterogeneity of outcome reporting. There is low- to very low-quality evidence that infraorbital nerve block with lignocaine or bupivacaine may reduce postoperative pain more than placebo and intravenous analgesia in children undergoing cleft lip repair. Further studies with larger samples are needed. Future studies should standardise the observation time and the instruments used to measure outcomes, and stratify children by age group.

Plain-language summary: We included eight studies with a total of 353 boys and girls, who ranged in age from 1 month to 13 years. These studies had been published up to June 2015. Three studies compared nerve block with sham block. Three studies compared nerve block with injected analgesics, and two studies compared nerve block with local anaesthesia. The children who received the infraorbital nerve block (with lignocaine or bupivacaine) had less pain and more time between finishing surgery and needing more analgesics. These children also had less need for analgesics than those who received the sham block. The children who received the infraorbital nerve block also had less pain and were able to eat sooner than those who received injected (intravenous) analgesics. The nerve block did not appear to alter heart rate, breath rate, and blood pressure. Five out of eight studies found no unwanted side effects after the nerve blocks; the other three studies did not mention side effects. The overall quality of the evidence was low or very low due to the small number of children included in the studies and differences between the studies (heterogeneity) regarding the types of intervention, the observation time, and the forms of measuring and describing the outcomes. Further studies with larger numbers of children are needed.