An Australian prospective cohort study of risk factors for severe perineal trauma during childbirth
Introduction
Perineal trauma after childbirth can cause short- and long-term complications for women. Severe perineal trauma can cause long-term complications, such as involuntary loss of faeces and flatus. After third-degree perineal tears, up to 85% of women have persistent sphincter defects and up to 50% have anorectal complaints (Sultan et al., 1993b; Haadem and Gudmundsson, 1997; Poen et al., 1998). There is increasing evidence that instrumental delivery is a risk factor for severe perineal trauma (Sultan et al., 1993a, Sultan et al., 1993b; MacArthur et al., 1997; Donnelly et al., 1998). Randomised trials have shown that episiotomy is not effective in reducing the rate of severe perineal trauma and may indeed be harmful (Harrison and Brennan, 1984; Sleep et al., 1984; House et al., 1986; Sleep and Grant, 1987; Klein et al., 1992; Argentine Episiotomy Trial Collaborative Group, 1993; Eltorkey et al., 1994). There is also evidence that the lithotomy position, fetal malpositions, fetal macrosomia, certain racial and ethnic groups (Rizk and Thomas, 2000; Goldberg et al., 2003), perineal body length (Deering, et al., 2004), women of low socio-economic status and very young teenagers are more likely to sustain perineal trauma (Renfrew et al., 1998).
In 1998, midwives and doctors at a tertiary maternity unit in Sydney, Australia, became concerned that their severe perineal trauma rate (1.9%) was one of the highest in the state of New South Wales (NSW) (NSW Health, 1998). This was despite a relatively low episiotomy rate of 11.8%, compared with 18.1% for NSW and an instrumental delivery rate of 11.8%, compared with 10.5% for the State. The high numbers of women from Asian backgrounds (19%) (NSW Health, 1998) giving birth in the maternity unit was hypothesised by many of the midwives and doctors to partly explain the high severe perineal trauma rate. This study was designed to identify the risk factors for severe perineal trauma in this population in order to help midwives and doctors reduce the rate, improve their practice and thereby contribute to the improved well-being of childbearing women. It was also hoped that a prospective study would ensure correct identification of all severe perineal trauma and an accurate incidence could be determined.
Section snippets
Design
A prospective cohort study was conducted over a 2-year period.
Setting
The hospital in which the study was undertaken is situated in central Sydney and cares for a significant proportion of women from non-English-speaking backgrounds (NESB). More than 45% of women are from NESBs, with 19% being born in an Asian country (NSW Health, 1998). ‘Asian’ was defined as being born in the following countries: China, Vietnam, Hong Kong, Indonesia, Japan, Laos, Cambodia, Taiwan, North Korea, South Korea, Thailand,
Findings
The overall incidence of severe perineal trauma in the sample was 2% (n=134). There were 122 third-degree tears (91%) and 12 (9%) fourth-degree tears. There was one repeat third-degree in the 2-year study period. Severe perineal trauma remained stable during the 2-year period.
No significant difference in mean maternal age was found between women who had severe perineal trauma and those who did not. Women who had severe trauma were less likely to have private health insurance, more likely to be
Discussion
This study has a number of limitations. The way women from individual Asian countries were categorised under one classification of ‘Asian’ makes individual analysis difficult. Individual ethnic variations are lost in such a classification system. As country of birth rather than ethnicity is recorded, some women who were classified as non-Asian could be second-generation Asian women born in Australia. Nonetheless, this system of classification was seen as a way to further explore this issue with
Conclusion
In this study, being primiparous, being of Asian ethnicity or having instrumental births put women at increased risk of sustaining severe perineal trauma during birth. In order to try and reduce the incidence of severe perineal trauma, effort needs to be made to reduce the incidence of instrumental deliveries. More research is needed into methods for reducing the incidence of severe trauma in women of Asian ethnicity; into reducing oedematous perineums during birth; the effect of fear and lack
Acknowledgment
The authors would like to thank the midwives involved in the study.
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