Congenital chest malformations are rare and can range from small, asymptomatic entities to large masses that require immediate surgery. Malformations of the developing chest cavity can often present as hybrid conditions, meaning that several of the following conditions can be present at one time.
Fetal chest malformations are typically diagnosed through fetal sonography, and when a condition is detected, an MRI can provide more precise imaging to allow for the best treatment plan.
Bronchopulmonary Sequestration (BPS)
In bronchopulmonary sequestration, a mass of abnormal lung tissue forms either inside (intralobar) or outside (extralobar) of the unborn baby’s lungs. It may not cause any problems for the baby or may even shrink on its own.
In other cases, the mass may cause a condition where extra fluid can build up in the amniotic sac or in the baby’s chest and abdomen, and this can be a life-threatening situation. Careful monitoring is the best prenatal treatment and will begin with a more detailed ultrasound to rule out other diagnoses and determine if other conditions are present as well.
After evaluating the baby, the care team will develop a treatment plan. In many cases, the mass can be surgically removed after birth. However, if the mass is impeding blood flow, restricting lung growth, or preventing normal heart function, then treatment before birth may be necessary.
Congenital Pulmonary Airway Malformation
A congenital pulmonary airway malformation, or CPAM, is a mass of abnormal fetal lung tissue that develops during pregnancy and does not function like normal lung tissue. The lesions can change in size and appearance throughout the pregnancy, and they may be solid or filled with fluid.
CPAM is usually detected during routine ultrasound, and follow-up tests will often include an MRI and fetal echocardiogram. In-utero treatment options may include steroid treatment to slow the growth of lesions, draining the cysts using thoracentesis, fetal surgery to remove large lesions, or early delivery.
Cystic Adenomatoid Malformation
A congenital cystic adenomatoid malformation, or CCAM, is an abnormality of one or more lobes in the lungs. Instead of functioning as normal lung tissue, it forms an area of both solid tissue and fluid-filled cysts. CCAMs can develop on either side of the lung but usually do not occur on both sides.
In most cases, CCAMs either shrink on their own or are small enough to not cause a problem. They are usually benign, and, rarely, can become cancerous later in life. Since the cystic area can also become infected and cause pneumonia, it is usually advised to surgically remove CCAMs after birth.
While most cases can be treated after birth, severe cases that affect the baby’s heart function may require fetal intervention before birth.
Congenital Diaphragmatic Hernia (CDH)
A congenital diaphragmatic hernia (CDH) occurs when the diaphragm, the muscle separating the chest from the abdomen, doesn’t properly develop. This causes a hole in the diaphragm where the stomach, intestines, or other abdominal organs can enter the chest.
This condition occurs in about 1,600 babies every year. In severe cases, it can restrict lung development, which can threaten the baby’s survival. With early detection, the baby’s CDH can be monitored to determine if it will be necessary to have an early delivery or if fetal intervention is required.
Treatment before birth can include fetoscopic endoluminal tracheal occlusion, or FETO, which is an advanced surgery to promote lung development before birth.
The most severe cases may require a specialized delivery that is called an EXIT-to-ECMO procedure to ensure a seamless transition to postnatal life. After the baby is born, a breathing tube and a tube from the mouth or nose to the stomach are placed to help expand the lungs. Surgery to close the CDH is usually done in the first week of life.
Esophageal Atresia and Tracheoesophageal Fistula (EA/TEF)
When the esophagus, the tube that carries food from the mouth to the stomach, doesn’t develop properly, it can result in esophageal atresia/tracheoesophageal fistula (EA/TEF). Usually the esophagus and the trachea (also known as windpipe) begin as a single tube and then divide into two separate passageways. When they do not separate, EA/TEF occurs.
EA/TEF can be the result of a genetic syndrome or chromosomal abnormality, which may cause it to appear more than once in a family. It can also be a condition that is not inherited, and the baby could be the only individual affected. EA/TEF occurs in around 1 out of every 4,000 babies. It is sometimes diagnosed via fetal ultrasound, but many times it is not confirmed until after birth. There is currently no fetal intervention for EA/TEF, but various monitoring techniques will help to determine the baby’s optimal postnatal treatment. EA/TEF usually requires surgery within the first week after birth to allow the baby to properly feed and prevent the lungs from being damaged by esophageal fluids.
Pleural Effusion
When fluid accumulates abnormally in the chest cavity of the fetus, it is referred to as a fetal pleural effusion or a fetal hydrothorax. The cause of fetal pleural effusions is oftentimes unknown, but some known causes are infection, heart conditions, abnormal lymph drainage, lung issues, or chromosomal abnormalities. In severe cases of fetal pleural effusion, the fluid can hinder the development of the lungs or cause fetal heart failure. If a pleural effusion is discovered during ultrasound, the pregnancy will be closely monitored with additional ultrasounds to evaluate the severity of the fluid collection. An echocardiogram will also be performed to check the baby’s heart function. An amniocentesis may be advised in order to look for chromosomal abnormalities.
In many cases, no treatment will be needed, but if an ultrasound indicates that there is enough fluid to cause the heart or lungs to compress, the fluid may need to be drained in a procedure called a thoracentesis. After delivery, the baby will be evaluated and a treatment plan will begin. Most cases of fetal pleural effusion are mild, and the majority of children affected by it grow up with normal lung function.
Pulmonary Agenesis
Pulmonary agenesis occurs when one or both of a baby’s lung buds fail to develop, and it can result in the complete absence of one or both lungs. Pulmonary agenesis is usually diagnosed with a sonogram. Once detected, it is common to have an ultrasound, fetal MRI, and a fetal echocardiogram. If pulmonary agenesis occurs in both lungs (bilateral), it is always fatal. However, babies have the potential to survive long-term with pulmonary agenesis of one lung (unilateral). Unilateral pulmonary agenesis can be associated with other abnormalities, such as heart defects, so it is important to monitor the baby in order to create a holistic treatment plan. Babies with unilateral pulmonary agenesis might need respiratory support following birth.