When a diaphragmatic hernia occurs what is actually happening to the organs?

Herniates into chest: This is a type of hernia that is not visible on the outside. The diaphragm is a large muscle that separtates the chest from the abdomen. There is normally a small opening in it to allow the esophagus to enter the abdomen. If this opening enlarges for any reason, the the stomach can actually start to slip up into the back of the chest cavity. If the opening is large enough, other organs will too.

Abnormal position: A diaphragmatic hernia is a hole in the muscle that separates the abdomen from the chest cavity. Intestines get into the chest and affect the lung development so that infants have insufficient lung tissue to survive, this is called pulmonary hypoplasia. The intestines also are malrotated but this is or lesser consequence.