This occurs when there is an inability to deliver the shoulder after the head has been delivered. This condition is associated with: a large fetus - any cause of macrosomia increases the risk - in diabetics the fetal head may be of normal size but the body is disproportionately large and the shoulders fail to enter the pelvis as the head is delivered; post-mature fetus; short cord; rotational forceps delivery - this may occur because there is some degree of disproportion and the fetal head has failed to pass the pelvic outlet. Birth asphyxia may occur.

Management:

• an obstetrician should be urgently summoned to the delivery room. This is an obstetric emergency that requires prompt action by a skilled practitioner.
• the mother is placed in lithotomy with her buttocks supported on a pillow over the edge of the bed. A large episiotomy is made.
• an assistant firmly applies suprapubic pressure directing the fetal head towards the floor. If delivery has still to be made then check that the anterior shoulder is under the symphysis. If not then an attempt may be made to rotate the anterior shoulder under this point (the point where the diameter of the outlet is widest) before repeating traction. If this is not possible then a rotation of the fetus through 180 degrees may be attempted so that the previously posterior shoulder now lies anteriorly.