Obstetric Pelvic Floor Trauma

Obstetric levator ani muscle injury and trauma to connective tissue and nerves are risk factors for pelvic floor dysfunction later in life. Levator injury is usually occult at the time of birth, and it cannot be repaired even when identified. Later, injuries can be visualized with 3D/4D transperineal ultrasound and magnetic resonance imaging (MRI). We distinguish between macrotrauma (levator avulsion) and microtrauma. Both result in a larger levator hiatus, facilitating descent of the pelvic organs. Levator injury is strongly associated with pelvic organ prolapse, failure of ring pessary treatment, need for surgery at younger age, and recurrence of prolapse after surgery. Levator injury is also associated with vaginal laxity and sexual dysfunction, and less often with urinary and anal incontinence. Forceps-assisted vaginal birth is the strongest obstetrical risk factor for levator injury, whereas vacuum carries the same risk as spontaneous vaginal birth and should therefore be preferred. Mediolateral episiotomy seems to be protective. Levator injury is associated with weaker pelvic floor muscle contraction. However, even an injured muscle can contract, and pelvic floor exercise might protect against pelvic floor disorders in women with muscle injury.