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Pulmonary Sequestration Learn More

• What is pulmonary sequestration?
• What is the outcome for a fetus with pulmonary sequestration?
• How serious is my fetus’s pulmonary sequestration?

What is pulmonary sequestration?

A pulmonary sequestration (also known as bronchopulmonary sequestration) is a cystic piece of abnormal lung tissue that does not work like normal lung tissue. They usually appear next to the lung (extrapulmonary, aka extralobar sequestration) or within one part of the lung (intrapulmonary, aka intralobar sequestration). We do not know what causes one part of the lung to develop abnormally. The cystic tissue involved will never function as normal lung tissue. There are several types of cystic lung disease including congenital cystic adenomatoid malformation (CCAM), pulmonary sequestration, and defects that are a mixture of these two. The abnormal piece of lung can be microcystic (many small cysts) or macrocystic (several large cysts).  Pulmonary sequestrations are distinguished from CCAMs by a blood vessel that comes directly from the main artery (aorta).

What is the outcome for a fetus with pulmonary sequestration?

Pulmonary sequestrations vary in size at presentation and can change throughout the pregnancy. The diagnosis is made by prenatal ultrasonographic findings of an echogenic (bright) mass appearing in the chest of the fetus. The mass may displace the heart from its normal position or push the diaphragm downward, but the key feature of a sequestration is the finding of an artery leading from the cystic mass directly to the aorta. This is what distinguishes a pulmonary sequestration from a CCAM.

The majority of these fetuses have a very good outcome.   Pulmonary sequestrations remain the same size or grow with the fetus, but usually do not cause severe problems, probably because there remains enough room for the normal part of the lung to grow. The mass may shrink in size before birth. In all these cases, the outlook for a normal life is excellent. These fetuses should be followed closely, delivered near term, and the pulmonary sequestration removed surgically after birth.

Those who do not have hydrops when the lesion is first detected must be closely followed (link: becoming a patient) by doing ultrasounds at least every week to look for the development of hydrops.  If they do not develop hydrops, we continue a “wait-and-see” attitude with close follow-up.  Many of these lesions will begin to decrease in size before 26 weeks of gestation and almost all can be safely dealt with after birth at a tertiary perinatal center.  Some lesions will even take care of themselves entirely. 

A small number of fetuses with pulmonary sequestrations may develop large pleural effusions (excess fluid in the chest cavity) and even signs of heart failure (hydrops). Unlike CCAM that cause trouble by virtue of their size, pulmonary sequestrations cause trouble by virtue of the high blood flow through the tumor. These are the only fetuses who require treatment before birth. 

Maternal Mirror Syndrome

In cases with extreme fetal hydrops, the mother may be at risk for maternal mirror syndrome, which is a condition where the mother's condition mimics that of the sick fetus. Because of a hyperdynamic cardiovascular state, the mother develops symptoms that are similar to pre-eclampsia and may include vomiting, hypertension, peripheral edema, proteinuria and pulmonary edema. Despite resection of the anomaly, maternal mirror syndrome may still occur.

How serious is my fetus’s pulmonary sequestration?

In order to determine the severity of your fetus's condition it is important to gather information from a variety of tests and determine if there are any additional problems. These tests along with expert guidance are important for you to make the best decision about the proper treatment.

This includes:

1. The type of defect—distinguishing it from other similar appearing problems.
2. The severity of the defect—is your fetus’s defect mild or severe.
3. Associated defects—is there another problem or a cluster of problems (syndrome).

Amniocentesis may be necessary for chromosome testing. Sonography is the best imaging tool, but is dependent on the experience and expertise of the operator. Magnetic resonance imaging may be necessary in some cases. Many problems are first detected during routine screening procedures performed in your doctor’s office (amniocentesis, maternal serum screening, routine sonography), but assessment of complex usually requires a tertiary perinatal/neonatal center with experience managing complex and rare fetal problems. We can work with your doctor to find a center convenient for you.