European Journal of Obstetrics & Gynecology and Reproductive Biology
Changing incidence of anal sphincter tears in four Nordic countries through the last decades
Introduction
Anal sphincter rupture (ASR) is a serious complication of vaginal delivery and leads to anal incontinence in 40–59% of cases [1], [2], [3]. Primiparity, macrosomia and instrumental vaginal delivery seem to be the most important risk factors. Median episiotomy increases the risk of anal sphincter tear but several reports show that mediolateral episiotomy might reduce the risk [4], [5], [6]. Statistical data show increasing incidences of anal sphincter rupture in the Nordic countries over the last decades but the reasons are unknown. Both newborn babies and mothers are heavier than before, mothers are older and epidural analgesia has become more usual, but at the same time the caesarean section rate has increased. Accoucheurs failing to provide perineal protection has been discussed as a potential reason [7]. The aim of this study is to describe the changes in four Nordic countries and discuss the reasons for the development.
Section snippets
Materials and methods
Data from the national birth and hospital registries were sampled from Finland (Hospital Discharge Register 1987–2007 and Medical Birth Register 2004–2007 (THL)), Norway (Medical Birth Register, National Public Health Institute), Sweden (Medical Birth Register, National Board of Health and Welfare) and Denmark (Medical Birth Register, National Board of Health). The validity of data is quality assured by validity declarations in each medical birth registry and also in several studies [5], [7],
Results
Fig. 1 describes the development of the prevalence of anal sphincter tears in the Nordic countries. A statistically significantly increasing trend was observed in all countries (p < 0.001) until year 2004. The results were alike using all three analyzing methods. In Norway, Sweden and Denmark the rate of anal sphincter tears has been significantly higher than in Finland during the observed period (p < 0.001).
The Danish incidence was not available in the birth register before 1997, but Moller Bek et
Discussion
The medical birth registries in Denmark, Finland and Sweden have a validity declaration that presents their control system. Several clinical trials and methodogical studies have been conducted and published to validate the data in these registries [5], [7], [8], [10], [11], and data coming from registries have been shown to be reliable.
The incidence of ASR has increased significantly in Finland, Denmark, Norway and Sweden from the middle of 1990s, but the frequency in Denmark, Norway and Sweden
Conclusion
There is a significant difference among the Nordic countries in the incidence of anal sphincter tears and a significant increment in the incidence over three decades. The most important risk factors, primiparity, macrosomia and frequency of instrumental delivery, are similar in all the investigated countries. Perineal protection and delivery technique are very little discussed as a reason for the increment of ASR in the publications that we found. Changed attitudes to protecting the perineum
Acknowledgements
We highly appreciate the work of the four Nordic Medical Birth Registries gathering the data. Without this the present article would have been impossible to write.
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