TEMPORAL TRENDS AND RISK FACTORS FOROBSTETRIC ANAL SPHINCTER INJURIES - A RETROSPECTIVE ANALYSIS OF ANATIONAL REGISTER
M. MARSCHALEK1, C. WORDA 1,L. KUESSEL 1, H. KOELBL 2, W. OBERAIGNER 3,H. LEITNER 3, J. MARSCHALEK 1, H. HUSSLEIN4;
1Department of Obstetrics andGynecology, Med. Univ. of Vienna, Vienna, Austria, 2Dept.of Gen. Gynaecology and Gynaecologic, Vienna, Austria, 3Departmentof Clinical Epidemiology Tirol Kliniken, Austrian Perinatal Registry,Innsbruck, Austria, 4Med. Univ. Vienna, Vienna, Austria.
Introduction: Several studieshave reported an increase of obstetric anal sphincter injuries in thelast decades, which could amongst others be due to the improvement ofdiagnostic attention and documentation. Besides the known riskfactors, which include high birthweight, operative vaginal deliveryand prolonged second stage of labour, maternal age might be anindependent risk factor for obstetric anal sphincterinjuries.
Objective: To describe time trends and riskfactors regarding the incidence of obstetric anal sphincter injuriesin primiparous women.
Methods: In this population-basedcohort study of the Austrian perinatal registry we analysed 168 137primiparous women with term, singleton, cephalic, vaginal deliverybetween 2008 and 2014. Multivariate regression model methods wereused to identify risk factors for obstetric anal sphincterinjuries.
Results: Between 2008 and 2014 there was anincrease in the rate of obstetric anal sphincter injuries (2.1% vs.3.1%, p<0.01), vacuum assisted deliveries (12.1 % vs. 12.8%,p<0.01) and caesarean section after labour (17.1% vs. 19.4 %,p<0.01), while the forceps rate (0.4% vs. 0.1%, p<0.01)decreased. Age >19 years, birthweight and operative vaginaldelivery were independent risk factors for obstetric anal sphincterinjuries. Epidural analgesia and position at birth were neither aprotective nor a risk factor. Mediolateral episiotomy at normalvaginal birth increased the risk for obstetric anal sphincterinjuries, whereas it was protective at the time of operative vaginaldelivery.
Conclusions: Like in other countries we found anincrease of obstetric anal sphincter injury over the last years. Therisk for obstetric anal sphincter injury increased with maternal age>19 years but remained stable in older age groups. The number offorceps delivery, the largest independent risk factor at birth, wasextremely low in this cohort, showing a decline over the years, whichmay have contributed to the low overall incidence of obstetric analsphincter injuries.
References: 1. BJOG : an internationaljournal of obstetrics and gynaecology. 2013 Nov;120(12):1516-25. 2.Obstetrics and gynecology. 2010 Jul;116(1):25-34. 3. Internationalurogynecology journal. 2016 Jan;27(1):61-7.
Figure1: Trends in the ratesof obstetric anal sphincter injury, caesarean section after labour,forceps and vacuum
Figure2: Age dependent rate(%) of obstetric anal sphincter injury