© 2018, GENASSIST, Inc.
By Keith S. Wexler, MBA, CFO, Business Development Director, GENASSIST, Inc.
Paul Wexler, M.D., F.A.C.O.G., Medical Director, GENASSIST, Inc.
Clinical Professor, Department of OB/GYN, University of Colorado Health Sciences Center
Clinical Professor, Division of Genetics/Dept. of Pediatrics, Univ. of Colorado/The Children’s Hospital
Background: A 35 year old female Gravida 2 Para 1 with one healthy child was referred by her OB/GYN for a fetal echocardiogram for a possible thickened myometrium at 22 weeks gestation.
Ultrasound showed a possible small echogenic mass in the lower left lung and a moderator band in the right ventricle which appeared “slightly higher in the right ventricle than is usually seen” giving the impression of a possible thickened myometrium.
The remainder of the fetal anatomical profile and fetal echocardiogram was within normal limits. Follow-up ultrasound was recommended in one month.
Case Study: The patient returned 5 weeks later at approximately 27 weeks gestation and ultrasound showed:
- Large left pleural effusion
- Deviation of the heart to the right lateral chest wall
- Slight fetal ascites
- Normal fetal movement
- Fetal heart rate of 146 beats per minute
- Fetal size 1 week 5 days greater than dates
- Biophysical Profile was 8 of 8
- Amniotic fluid volume was slightly increased.
The patient was referred to Pediatric Cardiology and Maternal Fetal Medicine the same day. The following findings were found:
- An echogenic, homogeneous mass in the left lower lung, measuring 3.4×2.8×2.6 cm with a large feeder vessel with arterial flow was seen on Doppler and color scan.
- Large left pleural effusion with mediastinal shift
Pediatric Cardiology evaluation confirmed a normal heart with normal cardiac function.
MRI was performed which confirmed a left bronchopulmonary sequestration with a large pleural effusion.
Seven days post initial diagnosis a left rocket thoraco-amniotic shunt was performed with good resolution of the left pleural effusion and only a slight mediastinal shift.
Weekly ultrasound studies with biophysical profiles were performed to monitor the patency of the shunt and fetal well being. At 37 2/7 weeks gestation, induction of labor was began with a Cook balloon for cervical ripening followed by oxytoin stimulation, artificial rupture of membranes and spontaneous delivery of a vigorous female infant, 2950 g, Apgar 8→9 after approximately a 4 hour labor. The thoraco-amniotic shunt was removed.
The pulmonary mass was less obvious on imaging studies and the feeding vessel was not seen. The infant continues to do well and will be followed to decide whether surgical intervention will be required.
Analysis: Rarely, a solid or cystic lung mass is found on routine fetal ultrasound – Congenital Cystic Adenomatoid Malformation (CCAM).
CCAM is the most common fetal lung mass, sometimes called Congenital Pulmonary Adenomatoid Malformation (CPAM). These are usually:
- Microcystic with small cysts measuring less than 5 mm each
- Macrocystic with cysts measuring greater than 5 mm
The cysts may change in size over time and often resolve by term.
Occasionally polyhydramnios (too much amniotic fluid) and/or pleural effusions (fluid in chest cavity) may be present which can displace the position of the heart.
Usually these patients can be monitored with serial ultrasound (every 4-6 weeks) and fetal intervention is not required.
Occasionally due to increasing lung fluid accumulation with decreased cardiac function, fetal surgery with cyst drainage or thoraco-amniotic sac shunting may be required.
Neonatal surgery may be required and resection of the abnormal and non-functioning lung tissue is recommended because of an increased risk for infection.
BrochoPulmomary Sequestration (BPS) is the second most common fetal lung mass. In these cases, the often echogenic lung tissue does not connect to the tracheobronchial tree and commonly gets it’s blood supply from a source other than the pulmonary arteries, often directly from the aorta. They may have a cystic component and a combination Bronchopulmonary Sequestration (BPS) and Congenital Cystic Adenomatoid Malformation (CCAM) can occur.
Hydrothrorax can occur and in-utero shunting may be required as in the case presented.
Serial ultrasound studies with biophysical profile of the fetus should be done and include:
- Amniotic fluid volumes (amniotic fluid indices)
- Placental and cord Doppler studies
- Non stress testing when appropriate
Despite the startling finding on ultrasound and the family trauma of dealing with the required close fetal surveillance and occasional fetal or neonatal intervention, fetal prognosis is usually quite good.
The prevalence of CCAM and BPS is not known but is approximately 3-9 per 10,000 births for CCAM and approximately 1 in 10,000 to 30,000 births for BPS.
The intralobular type is more common (70-85%) but usually presents later in childhood.
The extralobar type is more common in newborns (60%) and may be more common in males. The extralobular type can be intrathoracic or subdiaphragmatic and may be associated with diaphragmatic hernia, congenital heart disease, with or without other pulmonary abnormalities.
Both lesions have a small risk for malignant transformation which is estimated to be less than 1% with CCAM having a greater risk than BPS.