Symphysis pubis diastasis after normal vaginal birth: a case report.

The reported incidence of symphysis pubis diastasis following vaginal delivery is very low. The injury is more commonly caused by severe trauma from road traffic accidents and falls from heights. The reported incidence of peripartum pubic separation varies from 1 in 300 to 1 in 30,000 deliveries,1,2 although it may occur during the antepartum, intrapartum and postpartum periods. Mild separation of the symphysis pubis during pregnancy is considered physiological. A study of 14 women using computed tomography (CT) to assess anatomical changes in the pelvis following uncomplicated vaginal deliveries showed that 42% of the postpartum women had widening of the symphysis pubis, while none in the control group did.3 Separations of more than 10 mm are usually associated with tenderness and difficulty with walking, and are thought to be pathological.4 Factors contributing to rupture of the symphysis pubis during vaginal delivery are poorly defined. The injury is thought to be caused by the fetal head exerting pressure on the pelvic ligaments, which have been weakened or relaxed by the hormones progesterone and relaxin. It is thought to occur more commonly if manual pressure is applied to the pelvis in a latero-lateral and antero-posterior direction. The McRoberts manoeuvre, which is generally safe, may result in pubic symphysis diastasis, especially when excessive force is used or when there is prolonged placement of the patient’s legs in a hyperflexed position.5