What are the symptoms? Because of the hole, the bowel can go up through the diaphragm into the chest. This squashes the heart and both lungs. While in the womb, the placenta provides the oxygen for the baby, who will grow normally. However, the lungs may not develop normally, depending on how squashed they are and how long the bowel is in the chest. In some babies, the bowel only goes into the chest at delivery and so the lungs are normal. Other babies have lungs which are so poorly developed that the baby cannot survive. Most affected babies are in between and have a degree of breathing difficulty. Up to 50 per cent of babies with CDH have major associated problems, either with their heart, spinal cord, brain or with their chromosomes (see entry Chromosome disorders). These problems may mean the baby cannot survive. Long-term problemsSome babies have no problems following discharge. Up to 80 per cent have problems with gastro-oesophageal reflux of the stomach’s acidic contents, as a normal diaphragm is important in helping to prevent reflux. Some babies require further surgery to treat this. A few babies develop a neurological handicap, because of lack of inadequate ventilation by the underdeveloped lungs after birth. What are the causes? CDH occurs due to a failure of the parts of the diaphragm to come together and fuse properly during fetal development, allowing the abdominal organs to migrate up into the chest cavity. No single cause for this has been found, though some poisons and toxic chemicals can produce CDH in the laboratory. How is it diagnosed? Most babies with CDH are diagnosed before birth on routine scan. If termination is considered, then amniocentesis for chromosomal abnormality should be done, together with a detailed anomaly scan. Polyhydramnios (excess fluid around the baby) and the presence of the stomach and liver in the chest indicate a poorer outcome for the baby. If there are no associated abnormalities, continuation to end of pregnancy is often recommended, as there is a 50 to 60 per cent chance of the baby’s lungs being adequate. How is it treated? Most UK units stabilise the baby in intensive care on a ventilator (to help them breathe), so that the lungs and heart can be assessed. The baby is often kept in the unit for several days until the optimal moment for surgical repair is reached. Most surgeons repair the hole in the diaphragm via the abdomen. If there is enough diaphragm, the two edges of the hole are stitched together. If not, then a patch has to be inserted. Depending on the material used for the patch, this may not grow and may need replacement. Post-operatively, the baby will be more ill than before, because of the stress of the operation. After several days, or even weeks, if the lungs are good enough, then the baby can be weaned off the ventilator and will go home. Some babies go home with extra oxygen to breathe for a while, but as the lungs continue to grow after birth, this is eventually no longer required. Despite a lot of research, there has been almost no success with prenatal surgery, as the potential advantages of taking the bowel out of the chest to allow lung growth are outweighted by the disadvantages of premature delivery. Inheritance patterns and prenatal diagnosis Inheritance patternsThere is a recurrence risk of two per cent based on an incidence of 1 in 2,000 to 1 in 5,000 live births. This means that 98 per cent of families will not have a second baby with a CDH. Prenatal diagnosisRoutine ultrasound at 18 weeks can reveal CDH. Prenatal diagnosis allows transfer of the mother for assessment and delivery at a regional centre. The baby can then be electively delivered, resuscitated and undergo surgery, by a fully prepared team of neonatologists and surgeons. Is there support? CDH UK Tel: 0800 731 6991Email: firstname.lastname@example.orgWebsite: cdhuk.org.uk The Group is a Registered Charity in England and Wales No. 1106065, and Scotland No. SC042410. It provides information and support to anyone affected by Congenital Diaphragmatic Hernia. Group details last updated December 2014.