Abstract
Background
Recent trials demonstrated the safety and efficacy of sterile water injections to
provide relief from labour back pain. While four injections is the most common approach
variations in technique, such as employing two injections, are also used.
Aim
To determine if the analgesic effect of two sterile water injections is clinically
equivalent to four.
Methods
238 women in labour with a Visual Analogue Scale pain score (VAS) of 70 millimetres
(mm) (0 = no pain; 100 = worst pain imaginable) were randomised to two or four sterile
water injections. The primary outcome was pain measured on a VAS at 30 min post treatment.
A priori margin of equivalence was set at ±10 mm. Secondary outcomes included the
likelihood of achieving an at least 30% and 50% reduction in pain, birth and neonatal
outcomes.
Results
At 30 min post-injection the difference in VAS scores between the techniques was −5.97
(95% Confidence Interval [CI] −13.18–1.22). As the lower end of the CI exceeds the
margin of −10 mm equivalence was not demonstrated. Both techniques achieved an at
least 30% reduction in pain in over 75% of participants though duration of effect
was longer in the four injection group. There was no difference in other birth related
secondary outcomes.
Conclusion
Four injections provided a margin of benefit over two injections in level and duration
of analgesia.
Discussion
Four injections remains the technique of choice though two injections still provided
significant pain relief and would be suitable where it was not possible or desirable
to provide four.
Keywords
To read this article in full you will need to make a payment
Purchase one-time access:
Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online accessOne-time access price info
- For academic or personal research use, select 'Academic and Personal'
- For corporate R&D use, select 'Corporate R&D Professionals'
Subscribe:
Subscribe to Women and BirthAlready a print subscriber? Claim online access
Already an online subscriber? Sign in
Register: Create an account
Institutional Access: Sign in to ScienceDirect
References
- Caesarean delivery rates and analgesia effectiveness following injections of sterile water for back pain in labour: a multicentre, randomised placebo controlled trial.EClinicalMedicine. 2020; 25100447
- “No pain, no gain”: the experience of women using sterile water injections.Women Birth. 2017; 30: 153-158
- Sterile water injections for childbirth pain: an evidenced based guide to practice.Women Birth. 2018; 31: 380-385
- Comparison of a single vs. a four intradermal sterile water injection for relief of lower back pain for women in labour: a randomised controlled trial.Midwifery. 2013; 29: 585-591
- A new theory. A gate control system modulates sensory input from the skin before it evokes pain perception and response.Science. 1965; 150: 971-979
- Diffuse noxious inhibitory controls (DNIC). II. Lack of effect on non-convergent neurones, supraspinal involvement and theoretical implications.Pain. 1979; 6: 305-327
- Labour pain treated with cutaneous injections of sterile water: a randomised controlled trial.Br. J. Obstet. Gynaecol. 1999; 106: 633-637
- Subcutaneous versus intracutaneous injections of sterile water for labour analgesia: a comparison of perceived pain during administration.BJOG. 2000; 107: 1248-1251
- Subcutaneous sterile water injection for labour pain: a randomised controlled trial.Aust. N. Z. J. Obstet. Gynaecol. 2006; 46: 102-106
- Intracutaneous injections of sterile water over the sacrum for labour analgesia.Indian J. Anaesth. 2009; 53: 169-173
- Effectiveness of injecting lower dose subcutaneous sterile water versus saline to relief labor back pain: randomized controlled trial.Eur. J. Midwifery. 2018; 2
- Understanding equivalence and noninferiority testing.J. Gen. Intern. Med. 2011; 26: 192-196
- The visual analogue pain intensity scale: what is moderate pain in millimetres.Pain. 1997; 72: 95-97
- Ethical issues related to consent for intrapartum trials.Reprod. Health. 2017; 14: 31-33
- Would you like to participate in this trial? The practice of informed consent in intrapartum research in the last 30 years.PLoS One. 2020; 15e0228063
- The validation of visual analogue scales as ratio scale measures for chronic and experimental pain.Pain. 1983; 17: 45-56
- Intracutaneous or subcutaneous sterile water injection compared with blinded controls for pain management in labour.Cochrane Database Syst. Rev. 2012; 1
- The minimum clinically significant difference in visual analogue scale pain score does not differ with severity of pain.Emerg. Med. J. 2001; 18: 205-207
- Sterile water injection for labour pain: a systematic review and meta-analysis of randomised controlled trials.BJOG. 2009;
- CONSORT 2010 explanation and elaboration: updated guidelines for reporting parallel group randomised trials.Int. J. Surg. 2012; 10: 28-55
- Optimal strategies for reporting pain in clinical trials and systematic reviews: recommendations from an OMERACT 12 workshop.J. Rheumatol. 2015; 42: 1962-1970
- The patient observer: sterile water injections for labor pain.Birth. 2010; 37: 334-336
Article info
Publication history
Published online: February 10, 2022
Accepted:
February 1,
2022
Received in revised form:
February 1,
2022
Received:
November 25,
2021
Identification
Copyright
© 2022 Australian College of Midwives. Published by Elsevier Ltd. All rights reserved.
