Bochdalek hernia. Barium X-ray of a side view of the upper body of a patient with a Bochdalek hernia. A hernia is the protrusion of an organ or tissue through an abnormal opening. In this case part of the stomach (white, centre right) is protruding through the diaphragm, which separates the chest (centre to upper left) and abdomen (lower right). This is a congenital (present at birth) defect. It is usually detected soon after birth as the stomach can strangle the trachea (wind pipe) causing breathing difficulties. It is often fatal. Treatment is with surgical repair of the hole. Barium is a radio-opaque substance given as a liquid before an X-ray to highlight the digestive system.