Obstetric anal sphincter tears grade 3A – are they as innocent as we think?

Hypothesis / aims of study: Obstetric anal sphincter injuries (OASIS) are the most common cause of anal incontinence in women. Women with a history of OASIS have a higher incidence of anal incontinence symptoms. Grade 3A and 3B are generally considered to be a less symptomatic group when compared with women with 3C and 4 degree tears (1). This information is taken into account in patient counselling and will eventually be a major consideration in mode of delivery choice in all subsequent pregnancies. Grade 3A tears in particular are sometimes considered to be less significant for incontinence without there being any hard data to support this assumption. The aim of this study was to evaluate whether grade 3A tears really do signify a “better” group among the general group of women with OASIS, using four dimensional (4D) transperineal ultrasound in correlation with symptoms of anal incontinence.