Understanding Congenital Lung Malformation (CLM)
How common is CLM?
CLM is an abnormal development of a part of the lung. It can come in many different forms from big or little cysts (congenital pulmonary airway malformation or CPAM), to a solid mass (bronchopulmonary sequestration or BPS), to a combination (hybrid)
- 1 in 2,000 to 12,000 babies are born with CLM
- No known cause as to why they occur
- Usually detected early during screening ultrasound
- 6% of babies may have additional anomalies, typically involving the heart, kidneys, or digestive system
Fetal Center: the first step in CLM care
Multidisciplinary Evaluation: meet with MFM specialist, pediatric surgeon, neonatologist, and other experts who will care for your baby
Comprehensive Imaging: detailed ultrasounds and other tests when indicated to assess your baby's condition and help plan treatment
Coordinated Delivery Planning: our team works to ensure your baby receives immediate specialized care at birth
How is CLM evaluated?
- Regular monitoring with ultrasound surveillance throughout pregnancy is recommended to track changes
- Our medical team will use CVR (CPAM Volume Ratio) to help predict outcomes and plan care
- CVR compares the size of the CLM to the baby's head circumference allowing for tracking throughout pregnancy
- CLMs typically grow rapidly until around 28 weeks gestational age, then their growth slows down compared to the child. The CVR helps your care team track changes over time and make the best decisions for you and your baby's health
(pic: fetal ultrasound of large CPAM with arrow demonstrating the cyst)
How is a CVR > 1.6 treated prenatally?
When a fetus has a congenital lung malformation (CLM) with a CVR > 1.6, there is a high risk of heart failure (hydrops) and fetal demise, therefore, when indicated, treatment is initiated based on the characteristics of the lesion
- Maternal corticosteroids – first-line therapy for a microcytic lesion to reduce size and hydrops risk
- Thoracoamniotic shunt placement – used in large cystic lesions to drain fluid and collapse the cyst causing compression of the heart
- Open fetal surgery (lobectomy or mass resection) – rarely needed and reserved for refractory or life-threatening cases in a fetus prior to 27 weeks gestational age
- EXIT-to-resection – rarely needed, but allows resection while maintaining placental support if severe airway or hemodynamic compromise is anticipated at delivery
- C-Section-to-resection – Controlled Cesarean delivery of the child, followed by neonatal resuscitation and immediate resection of the lesion. Typically performed after 27 weeks gestational age in a child with significant compromise from the lesion
- Planned postnatal surgical resection - performed when the child is stable afterbirth within the first week of life
(pic: our fetal surgery team preparing for a C-section -to-resection)
How is a CLM treated postnatally?
Most often, a fetus with a CLM will remain stable throughout pregnancy and can deliver at term. Delivery and postnatal treatment will then depend on the maximum CVR obtained during prenatal care. Our experience at Primary Children's Hospital in Salt Lake City, Utah is extensive
Immediate Postnatal Management
- Routine delivery – vaginal delivery is generally safe if no signs of hydrops or airway obstruction prenatally
- Observation in the newborn period – many infants are asymptomatic at birth, especially with small or stable lesions
- Supportive care only if needed – oxygen, respiratory support, or NICU monitoring if mild distress develops
Diagnostic Evaluation
- Postnatal imaging – CT scan usually around 3 months of age to define lesion size, location, and anatomy
Definitive Management
- Elective thoracoscopic lobectomy/segmentectomy – typically performed at 3 - 6 months of age, even in asymptomatic infants, to:
- Prevent infection (recurrent pneumonia risk)
- Eliminate risk of malignant transformation (rare but possible, e.g., pleuropulmonary blastoma)
- Promote compensatory lung growth
(pic: Dr. Fenton with a patient who was treated with a CPAM)
Our Postnatal Utah Experience: Personalized Care Based on CV
