Congenital diaphragmatic hernia (CDH): diagnosis, treatment and outlook

The diaphragm is a thin sheet of muscle that helps us breathe and keeps the heart and lungs separate from the organs in the tummy. In CDH the diaphragm does not form as it should early in the baby's development. In some babies, organs from the abdomen such as the stomach, bowel and liver go through the hole. That is the hernia.

NHS England explains that these organs take up space where the lungs and heart should be, so the lungs do not grow as expected. Many babies with CDH also have pulmonary hypertension, which is high blood pressure in the lungs, making it harder for the lungs to take in oxygen.

Before birth the baby gets oxygen from the mother's blood through the placenta, so the lungs do not need to work. After birth the lungs have to supply the body with oxygen, and if they are small or underdeveloped they may not work properly.

NHS England says we do not know exactly what causes CDH and it is not caused by something you have or have not done. It is sometimes linked to other medical conditions, such as those affecting the baby's chromosomes (genetic information) and heart.

Cambridge University Hospitals describes it as a serious birth irregularity of unknown cause, associated with an underlying syndrome in some babies. Babies have genetic testing and scans to look for other abnormalities, and because not all syndromes can be detected before birth, the baby is also examined after birth.

NHS England says CDH is screened for at the 20-week scan (between 18+0 and 20+6 weeks of pregnancy), and sometimes noticed at a later scan or after the baby is born. Royal Manchester Children's Hospital says around half of babies with CDH are diagnosed on routine antenatal scans and the others soon after birth, usually because they are struggling to breathe, when an X-ray may show the problem.

If the scan suggests CDH you will be referred to a team of experts in caring for pregnant women and their babies before birth. NHS England says you will need a second scan to find out for sure, and the specialist team may offer extra tests such as chorionic villus sampling (CVS) or amniocentesis. These help look at the size and seriousness of the CDH, lung development, the heart and whether there is an associated chromosome condition.

Cambridge University Hospitals lists signs in a newborn: abnormal breathing, a rapid heart rate, blue discolouration from lack of oxygen (cyanosis), weak breath sounds usually on one side, and bowel sounds heard in the chest.

NHS England says babies with CDH need specialised medical attention in a unit experienced in caring for them, to help with their breathing, and will need an operation after birth, usually to close the hernia, once the baby is well enough. A team including neonatologists and paediatric surgeons will talk with you about the condition, possible complications, treatment and how to prepare for the birth.

Royal Manchester Children's Hospital says that if CDH was diagnosed before birth you will be offered a planned delivery. The neonatal team is in the delivery room and the baby is passed straight to them. They place a breathing tube connected to a ventilator and a nasogastric (NG) tube to empty the stomach, which gives the lungs more room to inflate. The leaflet says it is not likely a parent can hold the baby at first, because stabilising the baby quickly is important.

• Ventilator: most babies need help to breathe from birth. Some need extra nitric oxide gas and higher lung pressures (Manchester).

• Oscillation: a type of ventilation that pushes gas in and out very quickly, which can be gentler when very high pressures would otherwise be needed (Manchester).

• Pulmonary hypertension treatment: Cambridge says it can be treated with medication and an inhaled gas called nitric oxide, and it must improve before surgery can be considered.

• ECMO: a heart-lung bypass treatment used occasionally for the most serious cases, carried out in a small number of places in the UK, so a baby may be transferred.

Surgery can only take place once the baby is more stable and their heart and lungs are strong enough. Royal Manchester Children's Hospital says babies who need less breathing support may have surgery at 48 to 72 hours old, while others who need a lot of support often only become well enough after a number of days.

Under a general anaesthetic, the surgeon moves the organs from the chest back into the tummy and stitches the hole in the diaphragm. A patch or mesh is used to repair larger holes. Keyhole surgery (thoracoscopy) is sometimes used if the baby is well enough and the hole is small; Cambridge says it is only used if the baby was born at term and has good lung function.

Most babies stay on a ventilator for a number of days after the operation, depending on how well the lungs are working, and start milk feeds a few days after surgery. NHS England says the total stay in hospital varies from weeks to months, depending on the operation, recovery, complications, feeding and breathing needs.

CDH is a wide and varied condition. NHS England says it can be straightforward to treat, or complicated and more serious if there are other health issues as well. It gives the survival figure as about 5 in 10 (50%) babies, and notes the chance of doing well depends on how the lungs developed and whether there are other conditions. Royal Manchester Children's Hospital gives around 7 in 10. The figures differ between sources, so ask the specialist team what they mean for your baby.

NHS England says CDH can sometimes be linked with other conditions such as Down's syndrome, Edwards' syndrome, Patau's syndrome or heart conditions, in up to 1 in 10 (10%) cases.

For children who recover, Cambridge says the smaller the hernia, the lower the chance of long-term complications, and children with a diaphragmatic hernia usually do not have significant developmental problems unless there is an underlying syndrome or they were very sick with prolonged poor oxygenation.

The hospital leaflets list the following possible longer-term issues. Most children do not have all of them.

NHS England says you can talk to the team about the baby's CDH and your options, which include continuing or ending the pregnancy, and that only you know the best decision for you and your family. Whatever you decide, healthcare professionals will support you. If you continue, the specialist team will help plan your care and the birth and prepare you to take your baby home. If you end the pregnancy you should be offered a choice of where and how, and individual support.

Antenatal Results and Choices (ARC) is a national charity that supports people making these decisions, and CDH UK offers information and advice to families from diagnosis to childhood and beyond.

CDH is nearly always found in pregnancy or in the first hours after birth, and the care is planned by a specialist team. If you have been given a team contact, use it for any worry. If you are pregnant and have a diagnosis, or your baby has been discharged, and you notice breathing difficulty or blue lips or skin, call 999 rather than waiting. Abnormal breathing and cyanosis (blue discolouration from lack of oxygen) are the newborn signs the Cambridge leaflet lists. For any other worry, such as feeding or reflux, ask your team or NHS 111.

On the NHS, a baby suspected to have CDH is referred to a fetal medicine team and planned for delivery at a hospital with a neonatal surgical unit. After the operation the baby remains on the neonatal unit until ready for home. Because the surgery and intensive care are only available at specialist centres, this care is generally delivered within the NHS.

Some parents also seek a second opinion on prenatal scans or on the likely outlook. If you do, ask for the report to be sent to your own NHS fetal medicine team so that decisions about where to deliver stay joined up.