Abdominal air pockets. Chest X-ray of a 74 year old male patient showing air in the abdomen (dark masses at bottom right) a condition known as pneumoperitoneum. The air pockets are trapped below the diaphragm. The most common causes of pneumoperitoneum are gas escaping from a perforated bowel and suction of air through the female genital tract. Pneumoperitoneum is treated by removal of the air and repair of the underlying problem.