The cervix, vagina and perineum are vulnerable to trauma during descent and delivery of the baby. Indeed, some degree of trauma is almost inevitable, particularly in nulliparous women. In most cases the trauma is minor and full recovery can be expected, although perineal pain and superficial dyspareunia can persist for several weeks. However, long-term studies have shown that uterovaginal prolapse and urinary and faecal incontinence are not uncommon following the stretching and tearing of the pelvic floor musculature and the enclosed branches of the pudendal nerve. In addition, a surprising amount of blood can be lost in a short period of time from lacerations of the perineum, vagina and cervix and this is a major risk factor for post-partum haemorrhage. Knowledge of the predisposing factors and recognition and appropriate management of lower genital tract trauma are essential in the provision of safe obstetric care.

Factors associated with lower genital tract trauma include prolonged second stage of labour, early maternal pushing in the second stage of labour, macrosomia, persistent occipitoposterior position, assisted vaginal delivery (to a greater degree with forceps than with vacuum) and nulliparity.

Classification

The perineum extends from the sub-pubic arch to the coccyx. The perineum is divided into two anatomical sites: the anterior urogenital and post erior anal triangles. Anterior perineal trauma involves the labia, anterior vaginal wall, periurethral and periclitoral regions.