Comment: The quality of evidence is downgraded by study limitations (unclear allocation concealment, unclear sequence generation, and incomplete outcome data and selective outcome reporting bias) and by imprecise results (small trials with few patients).
A Cochrane review [Abstract] 1 included 7 studies with a total of 766 subjects. All trials reported on low back pain in labour only. All studies found greater reduction in pain for sterile water. However, failure to demonstrate a normal distribution for pain intensity or relief, and use of different scales, meant meta-analysis was inappropriate. One reported the number self-scoring 4/10 cm or more reduction in pain; significantly more had this outcome with sterile water (50% to 60%) than with placebo (20% to 25%).There was no significant difference between sterile water and saline for rates of rescue analgesia (RR 0.86, 95% CI 0.44 to 1.69). No study reported on women's satisfaction with pain relief. No adverse events were reported other than transient pain with injection, which was worse with sterile water.
Date of latest search: 13 October 2011
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