Artificial Rupture of the Membranes in Labour
Published: 30 July 2020
Published: 30 July 2020
Artificial rupture of the membranes, also known as breaking the waters or amniotomy, is common practice in many labour units around the world. In some places it is considered routine whilst in others it is used to speed up prolonged labour.
However, recent research suggests that this practice offers relatively little benefit to the mother and could potentially cause harm. So how should midwives approach this procedure?
Artificial rupture of the amniotic membranes (ARM) during early labour is one of the most commonly performed procedures in midwifery practice. The membranes are punctured with a crochet-like long-handled hook during a vaginal examination, releasing the amniotic fluid.
It is thought that rupturing the membranes releases chemicals and hormones that can stimulate and speed up contractions and consequently shorten the length of labour (Smyth, Alldred and Markham 2007).
ARM is also performed to allow the placement of fetal scalp electrodes if enhanced monitoring is required. It is a simple procedure performed when the cervix is partially dilated and effaced, with the fetus in a vertex presentation with the head or other presenting part well-applied to the cervix to avoid prolapse of the umbilical cord (Romm 2010).
As a precaution, fetal monitoring should always accompany the procedure, along with an evaluation of the colour of the amniotic fluid, which should be clear and free of meconium staining as this may indicate fetal distress.
Even though ARM has the potential to speed up labour, it is also an intervention that can cause a significant increase in pain as the baby’s head presses directly on the cervix for the remainder of the labour (RCM 2012).
ARM is a common midwifery procedure, often considered to be a routine part of actively managed labour. However, a recent Cochrane review was unable to draw firm conclusions about the use of amniotomy alone to shorten labour compared with women who received no intervention.
Some evidence suggested that the combined use of amniotomy and intravenous oxytocin is more effective than amniotomy alone, yet early rupture of the membranes is also found to be associated with an increase in the rate of caesarean sections (Romm 2010).
Contrary to these findings, however, Smyth, Alldred and Markham (2007) suggest that amniotomy performed early in labour also results in the earlier achievement of full cervical dilatation. These results, they suggest, are encouraging enough to call for further randomised controlled trials comparing the effects of both early and late amniotomies on the duration of labour.
Hiersch et al. (2014) notes that myometrial electrical activity is significantly enhanced following ARM and augmentation is most effective in women with a lower body mass index and initial lower basal uterine contractions.
Even though there are some suggested benefits, there is growing evidence that early rupture of the membranes is also associated with significant risks and disadvantages. According to the Royal College of Midwives (2012), it should only be used when there is abnormal progress in labour.
In contrast to previous studies, Storgaard and Uldbjerg (2009) found that ARM made no difference to the duration of the first stage of labour when evaluated in five randomised, controlled studies.
Other studies that have assessed the use of ARM in spontaneous labour also found no evidence of shortening of the first stage, concluding that routine amniotomy should not be recommended as part of standard labour management and care (Smyth, Markham and Dowswell 2013).
Similarly, the Royal College of Midwives (RCM 2012), commenting on a recent Cochrane review, concluded that not only was there no evidence of any statistical difference in the length of the first stage of labour, but amniotomy was also associated with a possible increased risk of caesarean section.
As well as increased maternal pain, Romm (2010) notes the following important risk factors associated with early rupture of the membranes:
Perhaps one of the greatest arguments against ARM is that mothers report it makes labour more painful. In a large study conducted by the National Childbirth Trust and reported on by the Royal College of Midwives (2012), 3000 women were surveyed. The results were unequivocal with two-thirds of women reporting an increase in the rate, strength and pain of contractions following rupture of the membranes.
Not only did these women find their contractions more difficult to cope with, but they also needed more analgesia and felt that the physiology of labour had been disturbed, leaving them feeling less satisfied with their labour overall (RCM 2012).
Overcoming the pull of custom and tradition can be a challenge when it comes to changing established practices. In the case of ARM, many researchers commented on the fact that midwives seldom asked permission of the mother before performing this procedure, or in many cases even discussed what was going to happen.
This unconsented intervention is one aspect of amniotomy that could and should be changed, and although communication skills have generally improved in recent years, there is now a call for amniotomy to only be performed with informed consent.
Again, many authors note that in light of recent research evidence, the potentially negative effects of ARM should be openly discussed and women should be given time to consider their options. In other words, the woman should not be asked for consent immediately before, or during a vaginal examination (RCM 2012).
Whilst it’s true that ARM can result in a labour that is slightly shorter than if the membranes are allowed to rupture spontaneously, ARM also results in greater pain, potentially leading to greater use of epidurals and a higher rate of caesarean sections.
Any intervention that interferes with a woman’s ability to cope in labour has significant implications for her physical and mental well-being, potentially causing her to feel traumatised and reducing her natural coping abilities.
This has led to many midwives suggesting that as long as it is clinically safe, other benign methods of stimulating a slow labour, such as positional changes and movement, should be tried first to avert the need for more intensive procedures.