Mode of Delivery and Perineal Trauma

Perineal trauma during childbirth is common. Although in the majority of cases perineal trauma does not have a major impact in the woman’s future pelvic floor function, severe degrees of childbirth trauma such as levator ani trauma and obstetric anal sphincter injuries (OASIS) may result in significant pelvic floor dysfunction including urinary and faecal incontinence. Levator ani muscle trauma is diagnosed in one third of women who have vaginal birth. Levator trauma can lead to weakening of the pelvic floor muscles, widening of the urogenital hiatus and pelvic organ prolapse in the future. In this chapter, the biomechanics of the second stage of labour and its effects on the pelvic floor and levator ani complex are discussed along with the effects of prolonged second stage on the pelvic floor. Different modes of delivery including instrumental deliveries have a different impact on the risk of perineal trauma and levator ani complex. The effect of fetal malposition and malpresentation and multiple pregnancies on perineal trauma as well as the role of episiotomy are also discussed in this chapter.