What is a Congenital Diaphragmatic Hernia?

Congenital diaphragmatic hernia, or CDH, is a kind of congenital malformation, or birth defect, where the diaphragm does not form properly. The diaphragm is a respiratory muscle that separates the chest from the abdomen and, in the case of a congenital diaphragmatic hernia, the muscle is incomplete, leaving a gap that may allow organs and intestines to move up from the abdomen into the chest. In severe cases this can mean that there is not enough room in the chest for the lungs to develop normally, with the result that they are smaller than usual, and contain fewer air sacs and blood vessels. Babies born with this condition normally have difficulty breathing, and may need to be kept alive using a ventilator or artificial lung, before surgery is carried out to repair the diaphragm and return displaced organs to the abdomen.

The commonest type of congenital diaphragmatic hernia is known as the Bochdalek hernia, and this most often occurs on the left side of the diaphragm, where it may allow the liver, spleen, large and small intestine and stomach to pass through into the chest cavity. Where a Bochdalek hernia is on the right, typically only a section of the large intestine, together with the liver, will move up from the abdomen. Sometimes what is called a bilateral hernia occurs, where both sides of the diaphragm are affected, but this is such a serious condition that the infant does not usually survive.

Another kind of congenital diaphragmatic hernia, the hiatus hernia, is rare. The tube leading from the mouth to the stomach, called the esophagus, normally passes through a hole in the diaphragm. A hiatus hernia involves part of the stomach pushing up through the same gap and protruding into the chest. There may be no symptoms, or there may be problems caused by acid regurgitating from the stomach.

Morgagni's hernia is a type of congenital diaphragmatic hernia that is slightly less rare than hiatus hernia. In Morgagni's hernia, part of the abdominal contents, usually a section of bowel, protrudes through a hole in the diaphragm known as the foramen of Morgagni. Sometimes there are only mild symptoms and the condition is not discovered until adulthood.

Treatment of congenital diaphragmatic hernia depends on the severity of the condition, as where the defect is only minor there may be no consequences and no need for action. In severe cases, where the lungs have been prevented from developing normally, the infant may have serious respiratory problems. If there is a chance of survival, the blood is oxygenated first using a type of artificial lung or a ventilator, then surgery is carried out to close the diaphragm and move any organs and intestines back into the abdominal cavity.