Cryotherapy for reducing the discomfort of sterile water injections: A randomised trial (CryoS trial)

The aim of this trial was to compare the effectiveness of a vapocoolant (rapidly cooling) spray to a chemical ice pack to usual care for reducing the injection pain experienced by labouring women when water injections are used to manage back pain in labour.

Participants were women in labour at term with a single, head down fetus and requesting analgesia for back pain in labour. Labour back pain occurs in approximately one third of all labours and sterile water injections, which is standard care at all participating sites, has been shown in placebo controlled trials conducted by members of our team, to provide significant pain relief. However, the administration pain experienced by women receiving water injections is significant and in known to act as a deterrent to use.

We randomised eligible women who have elected to have water injections for labour back pain and consent to participate to receive either vapocoolant spray, application of cold packs for 10 minutes prior to injections, or a control group of usual care in which neither the vapocoolant spray or cold packs are used. We expect the study to provide data on the best approach to mitigating the pain of water injections

Trial registration