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Congenital Diaphragmatic Hernia (CDH)

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Introduction Antenatal Postnatal West Midlands Data


The diaphragm is the muscular membrane that separates the chest cavity, from the abdominal cavity and the oesophagus and the major blood vessels pass through the diaphragm. The diaphragm develops in early fetal life, and is usually fully formed by 9 weeks gestation. In cases of diaphragmatic hernia, a hole allows structures that are usually within the abdomen to protrude into the thorax.

The most common site for diaphragmatic hernia is the left side, through which the stomach, bowel and liver can pass. The cause of congenital diaphragmatic hernia is essential unknown, but it often occurs in combination with other structural malformations, particularly heart defects. This abnormality is often caused by an underlying abnormality of the fetal chromosomes, particularly trisomies

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The use of ultrasound scanning has lead to some cases being diagnosed during pregnancy. The diagnosis rests upon obtaining clear images of the upper abdomen and chest. The most common finding is displacement of the fetal stomach, which can usually be clearly seen below the fetal heart, into the stomach. This sequence leads to displacement of the fetal heart to the right side of the chest, and can be distinguished from dextrocardia by examination of the orientation of the apex of the fetal heart. Large defects, with significant displacement of the fetal heart are most easily recognised, and therefore prenatal diagnosis will select a group with a relatively poor prognosis. The diagnosis of CDH is most commonly made at around 20 weeks, as it requires the fetal stomach to be seen, which is only usually apparent at approximately 18 weeks. Following a diagnosis, the fetus should be examined for other defects, particularly cardiac defects, which are present in up to 30% of cases. Even when the anomaly is apparently, isolated, fetal karyotyping is strongly recommended, as trisomy 21 and 18 are often associated with this defect.

The prognosis for CDH diagnosed at this stage of pregnancy is generally poor, with less than 40% of cases surviving the first few hours of life. The main cause of death is pulmonary hypoplasia, caused by compression of the fetal lungs in utero. This is difficult to predict with any degree of certainty. Fetal surgery has been attempted for this condition in the USA, with mixed results. The operation caries significant risk to both the fetus and mother and at this time there is no clear evidence that this intervention carries significant benefits. The procedure involves opening the uterus, opening the fetal chest and abdomen to allow a surgical repair to take place. Theoretically, this could allow development of the fetal lungs, but the practicalities of when and how to perform this type of major intervention remain to be clarified. No centres in the UK are currently offering this type of surgery.

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At birth, there is a transition from oxygenation by the placenta, to breathing using the lungs. If the lungs have been compressed by a diaphragmatic hernia then it will often prove impossible to adequately ventilate the baby, leading to death by multiple organ failure within the first few hours of life. The diagnosis of CDH is suspected in babies who seem well at birth but rapidly deteriorate and fail to respond to resuscitation. A chest x-ray will often show the displacement of the stomach giving the diagnosis in cases that have not been identified prenatally.

If the baby is able to survive the initial resuscitation but remains too unwell to undergo immediate surgery there may be a role for extra corporeal membrane oxygenation (ECMO), which is practice is a limited number of centres in the UK. ECMO allows additional oxygen into the circulation to stabilise the baby before surgery.

The long-term treatment for this malformation is surgical repair, which not technically complex, but is made hazardous by the condition of the neonate at the outset of surgery. If a child is considered well enough for surgery, the results are usually good. At least 80% will survive surgery and the majority of these will have completely normal outcomes, severe hypoxia always caries a risk of cerebral damage, which may in some cases lead to cerebral palsy and mental handicap.

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WM Data

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© Perinatal Institute 2011