Birth Small Talk

Talking about birth

Has the OASI bundle been a success?

Photo by freestocks on Unsplash

The findings of the much publicised, and criticised, “OASI Care Bundle” study conducted in the UK has just been published. The study aimed to establish if a package of several interventions (hence the name “care bundle”) could reduce the rate of severe perineal trauma. Severe perineal trauma includes spontaneous or surgical damage to the anal sphincter complex, also classified as third or fourth-degree perineal trauma. I can’t quite bring myself to use the terminology the authors do – obstetric anal sphincter injury – as I doubt that any obstetricians had their anal sphincters injured in the study.

The study was a response to concerns that the rates of severe perineal trauma in the UK had increased from 1.8% to 5.9% over a decade, though at least part of this increase might be due to changes in detection rates. The “bundle” consisted of a pamphlet for pregnant women, a “hands-on” approach to birth, performing episiotomy at a 60-degree angle when clinically indicated, and careful assessment of the perineum including rectal examination even when the perineum appeared intact. Evidence for the effectiveness of these individual components is limited. The use of warm perineal compresses, the only intervention with high level evidence proving a reduction in severe perineal trauma, was not included in the bundle.

To evaluate the success of the bundle, it was introduced to 16 maternity units and data were collected from prior to the introduction of the bundle and compared with data from after the bundle was implemented. 27,668 women who gave birth vaginally in the baseline part of the study and 27,392 women who gave birth vaginally in the evaluation phase made up the study population.

The baseline rate of severe perineal trauma was lower than the rates previously reported, at 3.3% of women giving birth vaginally. Following the introduction of the bundle, the rate was 3.0% – a statistically significant reduction (OR 0.8 95% CI 0.65-0.98). Subgroup analysis showed that the reduction in severe perineal trauma did not reach statistical significance for primiparous women, multiparous women, nor for those who gave birth by forceps or vacuum assistance. There was a reduction from 2.6% to 2.2% for women who gave birth without instrumental assistance (OR 0.75 95% CI 0.6-0.93, p=0.01) – yet strangely the authors of the paper describe this as showing no evidence of an effect of the care bundle. A typo perhaps?

The prevention of severe perineal trauma for 3 in 1000 women who gave birth vaginally in hospitals after the bundle was introduced isn’t really a stunning reduction in incidence. And I wonder if birthing women would accept having their midwife or doctor handling their perineum during birth and later performing a rectal examination as an appropriate “cost” to pay for this reduction. By way of comparison, a recent study focused on nine practice changes, none of which related to the placement of hands during birth, episiotomy use, or rectal examination. Instead they included such elements as monitoring and reporting of birth outcomes, a focus on good inter-professional practice, fetal monitoring education, and employing a midwife co-ordinator. The severe perineal trauma rate fell from 8.7% to 5.2% – 35 fewer cases of trauma per 1000 women. As a bonus, the rates of caesarean section, instrumental birth, and postpartum haemorrhage also fell.

There had been previous concerns that the use of episiotomy might increase as a consequence of the introduction of the package. This was reported on and was not the case, however the rate of episiotomy was relatively high at both time points (25.1% prior to and 24.5% after the introduction of the package).

Another criticism of the bundle has been the routine performance of rectal examination for women even when there is no visible perineal trauma. This was included out of concern that anal sphincter injury might occur with an otherwise intact perineum, but little evidence is available to indicate how common that might be, and there is no established treatment protocol available to address such an injury. Sadly, the study authors have provided no information on the frequency of anal sphincter injury detected by rectal examination of women with an otherwise intact perineum. This information is vital in counselling women so they can decide whether or not to have a rectal examination after birth.

The use of hot compresses on the perineum is a potential wild card in the research. This technique was not included in the package, leaving clinicians free to choose whether to use it or not. It is possible that the heightened attention to preventing perineal trauma encouraged practitioners to make use of warm perineal compresses, which are known to prevent severe perineal trauma. As this use of hot compresses was not accounted for in the research, there is no way to know whether this might explain the small reduction in perineal trauma.

Australia is currently trialling a similar bundle of care, with the inclusion of warm perineal compresses. What remains unreported are the voices of birthing women and of clinicians providing care in hospitals were the bundle has been introduced. The authors of the OASI study have promised that they will report on women’s experiences of care – I look forward to reviewing the evidence when it is available.

UPDATE: Sara Wickham has also written about the perineal bundle this week. She reviewed the other recent paper which looked at clinicians’ perspectives on the bundle. The issue of the “indignity” of rectal examination came up in this research too. Sara’s summary of the research can be read here.

Categories: New research

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2 replies

  1. I’ve got a thought…..let’s let women birth their way, less intervention, off their back and compare perineal trauma then!

    Liked by 1 person

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