Caesarean delivery rates and analgesia effectiveness following injections of sterile water for back pain in labour: A multicentre, randomised placebo controlled trial

Abstract

Background About a third of women experience severe back pain during labour. Injecting small volumes of intracutaneous sterile water into the lumbar region can be used to relieve this pain, however the procedure is controversial and previous reviews call for high quality trials to establish efficacy. We evaluated the impact on birth outcomes and analgesic effects of sterile water injections. Methods A multicentre, double-blind trial undertaken between December 2012 and December 2017 in one British and 15 Australian maternity units. Women experiencing severe back-pain in labour were assigned (1:1) by an independently generated randomisation schedule stratified by site to injections of either sterile water or saline placebo. Participants and caregivers were blinded to group allocation. The primary outcome was caesarean delivery rate. Main secondary outcomes included at least 30% or 50% reduction in self-reported pain scores at 30, 60 and 90 minutes after treatment. Intention to treat analysis were used and the level of significance for the multiple clinical outcomes was set at p <0.001 with the Bonferroni correction applied. The study is registered with the ACTRN Registry number, ACTRN1261100022195 Findings Between December 9, 2012, and December 15, 2017, 1166 women were recruited and randomised: 587 women received sterile water injections (SWI) and 579 a saline placebo. Seven women in the SWI group and 12 in the placebo group were excluded as consent was not completed, leaving 580 and 567, respectively, included in the analysis. The proportions of caesarean delivery were 17·1% (82 of 580) in the SWI group and 14·8% (82 of 567) in the placebo (RR 1·16, 95% CI 0·88–1.51; p = 0·293). At 30 min post treatment 60·8% (330 of 543) of women in the SWI group reported a 30% reduction in self-reported pain compared to 31·4% (163 of 520) placebo (RR 1·94, 95% CI 1·68–2·24; p =<0·001) and 43·3% (235 of 534) SWI reported a 50% reduction versus 18·1% (94 of 520) placebo (RR 2·39, 95% CI 1·95–2·94; p =<0·001). The analgesic effect of SWI compared to placebo remained significant at 60 and 90 min post-treatment. There were no significant differences in other maternal or neonatal outcomes. Interpretation Compared to placebo, injections of sterile water did not reduce rates of caesarean delivery. For the main secondary outcome of pain relief the intervention did result in significantly more women reporting at least 30% and 50% reduction in pain for up to 90 min. Water injections have no effect on birth outcomes though can be an effective treatment for the relief of labour-related back pain. Funded by the National Health and Medical Research Council.

Sterile water injections for relief of labour pain (the SATURN trial): study protocol for a randomised controlled trial

“…A recent placebo-controlled trial demonstrated the efficacy of sterile water injections into the lumbar region to relieve back pain in labour with no detrimental side effects [15]. Back pain in labour is different and may occur independently from abdominal labour pain [16].…”

“…Back pain in labour is different and may occur independently from abdominal labour pain [16]. Furthermore, the injections given into the lumbar region for back pain have no effect on abdominal contraction pain [15,17]. Injections of sterile water are acutely painful for a brief period, and this is known to act as a deterrent to both women and clinicians [18,19].…”

“…Normal saline for injection 0.9% will be used as the placebo solution. Normal saline is an active placebo resulting in some minor injection discomfort and some degree of analgesia, it has been used successfully in previous placebocontrolled trials [15,25]. The control arm (normal saline with vapocoolant) will reduce the chance of participant unbinding as all women will experience cooling effect of the vapocoolant and still have an equal chance of water or normal saline injections.…”

Effect of topical local anaesthesia on injection pain associated with administration of sterile water injections - a randomized controlled trial

“…Despite that SWI has been proven to be a highly effective pain relief method, without any adverse side effects [ 4 , 7 ], some women are doubtful of the method. Earlier it has been reported that some women rated the injection pain as more painful than the contraction pain [ 10 ] with a self-reported VAS of 90–100 mm [ 14 ].…”

“…Along with several smaller studies, a large double-blind, randomized controlled trial successfully demonstrated that SWI could provide effectively relief for low back pain during childbirth [ 7 ]. Clinical guidelines for the use of the procedure have earlier been published [ 4 ].…”