University Hospital Southampton NHS Foundation Trust

Congenital cystic adenomatoid malformation of the lung

We all have five parts to our lungs, known as lobes, two on the left and three on the right. Sometimes a problem occurs during development which can result in one of the lobes containing a group of fluid or air-filled spaces (cysts), rather than lung tissue.

The cysts are usually confined to one lobe but occasionally more than one lobe can be affected. The cysts can be detected on ultrasound before birth and have various appearances ranging from a small number of large cysts to a large number of small cysts.

Why does it occur?

This is a very rare abnormality only occurring in about 1 in 10,000 babies. We do not know why this happens. There is no evidence to suggest that it is caused by anything you have done or have not done during the pregnancy.

Congenital Cystic Adenomatoid Malformation of the lungHow may it affect my baby before delivery?

In some babies the cysts can enlarge quite rapidly during pregnancy resulting in major problems for the baby before birth. Occasionally babies with this condition do not survive the pregnancy. More often, however, the cysts do not grow rapidly and may not grow at all. In fact, in some cases the cysts may actually disappear completely before the birth and the baby will be born with no problems whatsoever. For this reason it is important to do repeat scans throughout the pregnancy.

What happens at the delivery?

Providing all goes well during the pregnancy, then there should be no need to alter the timing or method of delivery. There is no need for your baby to be delivered at the Princess Anne Hospital unless the scan suggests there may be breathing problems following delivery.

What happens after the delivery?

If the baby has no breathing difficulty after delivery:

Many babies have no problems whatsoever. X-rays will need to be done in the first day or two to determine whether any treatment is necessary.

If the x-rays show only minor changes and there are no breathing difficulties the baby will be discharged home after a few days and these babies usually remain perfectly well. We will arrange out-patient follow-up and for a more detailed x-ray (CT scan) to be performed in the next few weeks.

If this scan shows that the cysts have disappeared then no further action is necessary. If the cysts are still present we will discuss further options with you. Occasionally surgery may be advised. This is to prevent complications from the cysts such as infection. There have also been reports of growths developing in the cysts in later life.

If the baby does have breathing difficulty after delivery:

In some babies, the cysts press on the rest of the lung causing the baby difficulty in breathing. This may be quite minor, resulting only in rapid breathing, or can be more serious. Breathing may become more difficult in the first few days, so it is very important that the baby is observed carefully during this time.

In babies with breathing difficulty an operation is usually required. The  timing of the operation depends on how the baby is affected. The more difficulty there is with breathing, the quicker the operation is done. In some cases this results in the operation being performed in the first 24 - 48 hours of life, and in others the operation is deferred for a few days.

Very rarely, the cysts will have caused failure of the development of the rest of the lung and, despite surgery to remove the cysts, the baby may die.


During the  operation it is usual to remove the affected lobe of the lung. If this is required in the first few days of life the speed of recovery depends on how compressed the remaining lung has been prior to birth. Many babies recover in a few days while others may be in hospital for several weeks. The operation that is undertaken is a fairly major one but is usually very straightforward. The length of stay following surgery would vary from a few days to, in the most extreme cases, perhaps some weeks.

Although the operation itself will involve removing one of the five lobes of the baby’s lungs, this is an area that would not have been any use to the baby anyway and the remainder of the lung will grow to compensate for the piece that has been removed.

What are the long term effects and after care?

In the long term, provided that there have not been any extreme breathing difficulties at the beginning, the vast majority of these babies will be normal and do not have any long term problems with their lungs at all. They can grow up to be perfectly healthy normal children.

Following discharge from the ward, there will be regular check-ups in order to monitor your baby’s progress. An appointment for the Paediatric Outpatient department will be sent to you.

Parent to parent link

Many parents who have experienced this same condition with their baby have indicated that they would be willing to speak to other  parents. If you would like make use of this service please contact us for further information.


University Hospital Southampton NHS Foundation Trust produce guidelines as an aid to good clinical practice. They represent recognised methods and techniques of clinical practice, based on published evidence. The ultimate judgement regarding a particular clinical procedure or treatment must be made by the clinician in the light of the clinical data presented by the patient and the diagnostic or treatment options available. The guidelines issued are not intended to be prescriptive directions defining a single course of management and departure from the local guidelines should be fully documented in the patient's case notes at the time the relevant decision is taken.