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Open Access Study protocol

A randomised non-inferiority controlled trial of a single versus a four intradermal sterile water injection technique for relief of continuous lower back pain during labour

Nigel Lee14*, Peter Coxeter2, Michael Beckmann1, Joan Webster3, Vanessa Wright1, Tric Smith3 and Sue Kildea14

Author Affiliations

1 Mater Health Services, South Brisbane, Qld. 4101 Australia

2 Mater Medical Research Institute, South Brisbane, Qld. 4101 Australia

3 Royal Brisbane and Women's Hospital, Herston, Qld. 4029 Australia

4 Australian Catholic University, Banyo, Qld. 4014 Australia

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BMC Pregnancy and Childbirth 2011, 11:21  doi:10.1186/1471-2393-11-21

Published: 23 March 2011

Abstract

Background

Almost one third of women suffer continuous lower back pain during labour. Evidence from three systematic reviews demonstrates that sterile water injections (SWI) provide statistically and clinically significant pain relief in women experiencing continuous lower back pain during labour. The most effective technique to administer SWI is yet to be determined. Therefore, the aim of this study is to determine if the single injection SWI technique is no less effective than the routinely used four injection SWI method in reducing continuous lower back pain during labour.

Methods/design

The trial protocol was developed in consultation with an interdisciplinary team of clinical researchers. We aim to recruit 319 women presenting at term, seeking analgesia for continuous severe lower back pain during labour. Participants will be recruited from two major maternity hospitals in Australia. Randomised participants are allocated to receive a four or single intradermal needle SWI technique. The primary outcome is the change in self-reported pain measured by visual analogue scale at baseline and thirty minutes post intervention. Secondary outcomes include VAS change scores at 10, 60, 90 and 120 min, analgesia use, mode of birth and maternal satisfaction.

Statistical analysis

Sample size was calculated to achieve 90% power at an alpha of 0.025 to detect a non-inferiority margin of ≤ 1 cm on the VAS, using a one-sided, two-sample t-test. Baseline demographic and clinical characteristics will be analysed for comparability between groups. Differences in primary (VAS pain score) and secondary outcomes between groups will be analysed by intention to treat and per protocol analysis using Student's t-test and ANOVA.

Conclusion

This study will determine if a single intradermal SWI technique is no less effective than the routinely used four injection technique for lower back pain during labour. The findings will allow midwives to offer women requesting SWI during labour an evidence-based alternative technique more easily administered by staff and accepted by labouring women.

Trial Registration

ACTRN12609000964213