Saturday, 6 August 2016

Sterile Water Injections for Managing Back Pain in Labour

I was having a conversation with a woman via twitter about back pain in labour. The woman said the birth was 'excruciating' because of back pain. I mentioned the use of intradermal sterile water injections (ISWI) to alleviate back pain in labour. 

The woman said she had been offered them but decided against it because she was told that they "really hurt going in" and she was scared to have them.  

Another woman tweeted that she'd 
"never heard of those! I had two posteriors and the back pain was intense …"
It seemed a blog post on intradermal sterile water injections could be useful. 

Giving birth is an experience rich with emotional, physical and psychological sensations. How we cope with those sensations (or not) has many facets. 

Most women feel a strong pressure in their lower back as their baby’s head rotates and pushes the sacrum out on the way down the birth canal in second stage. I've been told that in Thailand, those sensations are known as 'the opening of the gate' – which is a wonderful description of the sacrum swinging back to allow the baby’s head to descend and turn as it meets the pelvic floor. 

Women who expect that sensation recognise that their baby is close to being born when they feel that pressure.  

That sensation is followed by a feeling that their hips are being pushed apart as the baby descends further down the woman’s pelvis and comes around the 's' bend. 

For some women, back pain, especially if it occurs in the first stage of labour, is 'intense' and can be unbearable. Some women can find it difficult to relax, ‘let go’ and welcome the sensations and impending birth of their baby with the pain they feel in their lower back in second stage. 

Movement, heat, water and counter pressure are some of the ways that women find useful to help them alleviate and/or manage the pain. Other techniques include positioning and/or lifting parts of the woman's pelvis to change the shape of the woman’s pelvis and to help shift the baby’s head’s position in the pelvis.   

Some women seek refuge in an epidural anaesthetic block.  

I first heard about the use of intradermal sterile water injections (ISWI) for back pain in labour when I was manager of a stand-alone birthing service.  I read an article by Peart, James and Deocampo (2006) in the journal Birth Issues and was fascinated. 

The main reason for women transferring in labour from our birthing service was to have an epidural to relieve intractable back pain when none of the usual strategies worked. Although the numbers of women transferring to the tertiary referral hospital were small, women would have preferred to stay at the birthing centre, so any ideas that could help them manage the sensations of labour were welcome. 

I invited Janice DeoCampo, one of the authors of the paper, to the birth centre and teach us what to do. We were delighted when she agreed to come. We invited midwives from the surrounding hospitals to be part of the workshop. About forty midwives enjoyed the day learning about this remarkable and non-narcotic pain-relieving technique. Janice told us she saw the technique used very effectively in Sweden and that was what fuelled her passion to bring the procedure back to Australia.  

We had a wonderful service manager, Dr Anne Saxton, who was very supportive and after much proposal writing and refining, we finally gained ethical clearance and permission from the health service for the new procedure to be midwife-initiated in all the hospitals in the region. A study by Lee (2012) found that despite a desire by midwives to use ISWI to help women in labour, few were actually doing so. In my experience there needs to be good support from maternity service management when negotiating the legal and bureaucratic requirements to get acceptance of this still relatively new, midwife-initiated procedure.    

So what is it? 

Intradermal sterile water injections (ISWI) are given under the skin, into the layer known as the dermis, as close to the surface (epidermis) as possible.  You can see those layers in the diagram below.  

Skin (source Wikipedia)
Sterile water (0.5ccs) is drawn up into 2 tuberculin syringes. The recommendations are that sterile water is injected via 25g needles, bevel up, in four sites; approximately 0.1- 0.2cc administered at each site (see diagram below from Peart, James & Deocampo, 2006). Two midwives are needed for the administration of the sterile water, both injecting the water at the same time.  When the water is injected in the optimal way, a small 'bleb' is raised in the skin which sends the signal to the spinal cord to switch on the 'gate' that controls deeper pain messages up the spine to the brain.

The history of the use of gate control methods of pain relieve is very interesting.

Counter irritation or ‘gate’ control methods of pain management
The earliest use of “counter irritation” was in 1945 (Gammon and Starr; Parsons and Goetzl) with the use of mustard plasters to reduce pain by inducing an analgesic effect. According to these authors, the best result occured when the counter irritant is administered directly over or near the vicinity of the pain site (Gammon and Star 1941).  In 1965 Malzack and Wall (1965) hypothesized that nerve impulses, evoked by injury, are influenced in the spinal cord by other nerve cells that act like gates, either preventing impulses getting through, or facilitating their passage. Intradermal sterile water injection (ISWI) is thought to trigger the gate control mechanism. 

As the skin is the outer barrier for the body, anything that threatens the skin gets transmitted to the brain quickly, shutting off the slower pain messages from inside the body, so the individual can take evasive action and escape the 'threat'. In 1975, Dr Michael Odent acknowledged the use of sterile water injections for sacral pain in labour having observed that pain itself is actually an obstacle to dilation. The best thing is that ISWI provides a form of non-pharmacological pain relief that has no harmful effects and they don't stop movement. The woman who uses ISWI for back pain can still move freely and is not hooked up to either intravenous fluids or continuous monitoring systems.

Controlled studies using sterile water injections has been conducted for their use in relieving pain from renal colic, phantom limb pain, chronic neck and shoulder pain from whiplash and chronic lower back pain. Well-designed RCT’s have consistently demonstrated a dramatic analgesic effect on lower back pain in labour from ISWI at 4 points in the lower back area, approximately corresponding to the borders of the sacrum. 

Women's satisfaction with this method does vary, but it is a simple and inexpensive way of providing a medication-free option to women who prefer to avoid or delay the use of epidural block (EDB) or for those women for whom the option of EDB is not available or not wanted. As ISWI doesn’t fit into classic understanding of pain relief, clinicians are sceptical until the obvious and dramatic relief has been witnessed. This simple measure deserves further evaluation but on the present available data would seem a worthwhile option for use as a non-pharmacological method to reduce lower back pain in labour. 

A systematic literature review (Fogarty 2008) found the following benefits of sterile water injections:
  • rapid and effective low back pain relief during labour
  • no apparent side effects
  • simple to use and a high level of success
  • non-pharmacological
  • decrease the use of epidural anaesthesia
  • delay the use of epidural anaesthesia
  • may be used while waiting for an anaesthetist
  • may decrease the caesarean section birth rate
  • may be used in first and second stage of labour
  • have applications for use in rural/remote areas and developing countries where alternative treatments are not available
  • have a role to play with their analgesic effect on pelvic floor one, cervical tension and fetal rotation 
·         While evidence suggests that ISWI are more helpful in the early stages of labour rather than later, anecdotally and experientially, they have been found to be just as effective in late first stage or second stage for women whose back pain interferes with pushing.  In fact, the woman's pelvis can relax so completely when the back pain is gone, the baby can rotate and emerge quite quickly after the injections are given!

Touching, massage or rubbing the area of injection is to be avoided as it defeats the purpose of using sterile water to get the ‘sting’, as the ‘sting is the thing’ that interrupts the deeper pain signals. Research by Lee et al, 2011) on the number of sites injected found that using the four sites as indicated in the illustration above is more effective, but also found to be more painful for women. In practice, we found two sites above and distal to the site of pain to be effective. We also found these injections could be used for intractable suprapubic pain in labour. 

When women indicate they want something for the back pain labour, they are asked to point to the site of their pain and rate their back pain before and after the water injections on the Visual Analogue Scale (VAS) below. 

We’ve found that the score has to be above 6 for the ‘sting’ of the actual injection to be considered ‘worth it’ by the woman.  In practice, it is rare for the intradermal sterile water injections to not have a positive effect on the reduction of pain for the woman, especially if her pain score was high.  Women are provided with an information sheet and a consent form for Intradermal sterile water injections in labour when they book into the service. Some people wonder why sterile normal saline isn’t used instead of sterile water, as the pain of injection would be less. The sting of the sterile water seems to be key to the ‘gate control’ mechanism of pain pathways and the normal saline would not therefore be as effective, if it was effective at all. 

Here's an interview about the technique on Belly Belly 

Despite our practical experiences with this procedure and the volumes of research so far, more information is needed on the effects of intradermal sterile water blocks on obstetric outcomes, women’s experiences, the effect of repeated injections, its mode of action and the effects of varying dosages, locations as well as the number of sites injected.

Have you had experiences with sterile water injections either as a midwife or a birthing woman? What were your experiences like? Do you recommend them? 

Fogarty, V. (2008) Intradermal sterile water injections for the relief of low back pain in labour – A systematic review of the literature, Women and Birth, 21 pp. 157-163.

Lee, N., Webster, J., Beckmann, M., & Gibbons, K. (2013). 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, 29 (6), 585-591.

Melzack, R., & Wall, P. (1965). Pain Mechanisms: A New Theory. Science, 150 (3699), 971-979. Retrieved from

Peart K, James W, Deocampo J: "Use of sterile water injections to relieve back pain in labour." Birth Issues 2006, 15 (1):18-22.
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