Shoulder dystocia xray video. Shoulder dystocia is a specific case of dystocia whereby after the delivery of the head, the anterior shoulder of the infant cannot pass below the pubic symphysis, or requires significant manipulation to pass below the pubic symphysis. It is diagnosed when the shoulders fail to deliver shortly after the fetal head. In shoulder dystocia, the baby's chin that presses against the walls of the perineum. Childbirth xray animation videos from medical animation experts Polymime.