What is the recommended fetal therapy for a pregnant woman diagnosed with a fetus having congenital cystic adenomatoid malformation (CCAM)?

Fetal Therapy for Congenital Cystic Adenomatoid Malformation (CCAM)

For CCAM with hydrops fetalis, macrocystic lesions should be treated with thoracoamniotic shunt placement or needle drainage, while large microcystic lesions causing hydrops should be treated with maternal betamethasone (12.5 mg IM every 24 hours for 2 doses) or dexamethasone (6.25 mg IM every 12 hours for 4 doses). 1

Risk Stratification and Treatment Algorithm

Macrocystic CCAM (cysts >5mm) with Hydrops

• Perform thoracoamniotic shunt placement or needle drainage of the large cyst(s) causing mediastinal shift and cardiovascular compromise 1
• This intervention can improve survival to >50% in hydropic cases 2
• If gestational age is near term (≥34 weeks), consider needle drainage immediately before delivery rather than shunt placement 1
• Macrocystic lesions have a more favorable prognosis than microcystic lesions, even when complicated by hydrops 3

Microcystic CCAM (cysts <5mm, solid appearance) with Hydrops

• Administer maternal corticosteroids: betamethasone 12.5 mg intramuscularly every 24 hours for 2 doses, or dexamethasone 6.25 mg intramuscularly every 12 hours for 4 doses 1
• Microcystic lesions are associated with poor prognosis and higher risk of fetal/neonatal death 3
• Open fetal lobectomy is technically possible before 32 weeks but should only be considered at specialized centers with this capability, as it carries significant maternal and fetal risks 3, 4

CCAM without Hydrops

• Serial ultrasound surveillance every 2-4 weeks to monitor for development of hydrops, polyhydramnios, or mediastinal shift 5, 6
• Approximately 38% of lesions appear to resolve and 29% decrease in size on serial imaging, though postnatal CT often reveals persistent abnormalities 6
• No prenatal intervention is indicated; plan for delivery at a tertiary center with immediate neonatal resuscitation and surgical capabilities 1, 3
• Overall prognosis is good with survival rates >90% in non-hydropic cases 5, 7

Critical Management Principles

Referral and Delivery Planning

• All CCAM cases with hydrops must be referred to a tertiary center with expertise in fetal therapy 1, 2
• Even non-hydropic cases should deliver at centers with pediatric surgery and neonatal intensive care capabilities 1, 3
• Maternal transport before delivery is preferable to neonatal transport after delivery 3

Monitoring for Complications

• Monitor for polyhydramnios and mirror syndrome (maternal preeclampsia-like syndrome), which indicate worsening fetal cardiovascular compromise 1
• Serial maternal blood pressure monitoring is recommended due to risk of mirror syndrome 1
• Development of mirror syndrome is generally an indication for delivery if gestational age permits 1

Timing of Delivery

• Hydrops developing before 32 weeks may be amenable to fetal intervention 1
• For stable non-hydropic cases, allow spontaneous labor at term 1
• If hydrops develops after 32-34 weeks, consider delivery rather than fetal intervention, depending on lung maturity 1

Common Pitfalls to Avoid

• Do not assume lesion resolution based on prenatal ultrasound alone: 60% of cases with apparent antenatal resolution still have abnormal chest X-rays, and 100% have abnormal postnatal CT scans 6
• Do not delay intervention in hydropic cases: hydrops indicates severe cardiovascular compromise with high mortality risk (>50% without intervention) 1, 3
• Do not confuse macrocystic and microcystic types: they require different interventions and have different prognoses 1, 3
• Do not perform fetal surgery for non-hydropic cases: the risks outweigh benefits when hydrops is absent 3, 7