Diagnosis of shoulder presentation

On abdominal palpation, the uterus appears broader and the height of the fundus is less than expected for the period of gestation, because the fundus is not occupied by either the baby's head or buttocks. You can usually feel the head on one side of the mother's abdomen. On vaginal examination, in early labour, the presenting part may not be felt, but when the labour is well progressed, you may feel the baby's ribs. When the shoulder enters the pelvic brim, the baby's arm may prolapse and become visible outside the vagina.