Chapter 118: Fetal Intervention and Surgery

In utero therapy · Obstructive uropathy · CDH · CPAM · CHAOS · SCT · Myelomeningocele · TTTS · Fetal centers
✅ Evidence-based fetal therapy · MOMS trial · FETO · EXIT procedures

✨ Fetal Intervention: Key Principles & Diagnoses

🧬 Obstructive uropathy
Posterior urethral valves (PUV). Vesicoamniotic shunt, fetal cystoscopy. Goal: restore amniotic fluid → prevent pulmonary hypoplasia.
🫁 Congenital diaphragmatic hernia (CDH)
FETO (balloon tracheal occlusion) improves survival in severe cases. TOTAL trial: FETO survival 40% vs 15% expectant.
🫀 CPAM / Lung lesions
CVR >1.6 and hydrops → maternal betamethasone, thoracoamniotic shunt, or EXIT. Prognosis depends on hydrops.
🧠 Myelomeningocele (MMC)
MOMS trial: prenatal repair reduces VP shunt (40% vs 82%) and improves motor function. Open or fetoscopic approach.
🔄 Twin-Twin Transfusion (TTTS)
Laser ablation of placental anastomoses. Quintero staging. Improves survival and neurologic outcomes vs amnioreduction.
🩺 SCT & CHAOS
SCT: high-output failure → fetal debulking/early delivery. CHAOS: EXIT-to-airway to secure airway before cord clamping.
⚡ Prenatal prognostic markers: LHR (lung-to-head ratio), O/E TLV, CVR (CPAM volume ratio), MCA Doppler for anemia, Quintero stage for TTTS.

🔍 Approach to fetal anomalies: from suspicion to fetal center referral

1
Prenatal ultrasound finding – Polyhydramnios, echogenic chest mass, enlarged bladder, ascites, hydrops, neural tube defect. Detailed anatomy + fetal echocardiography.
2
Risk stratification – LHR <25% (severe CDH), CVR >1.6 + hydrops (CPAM), oligohydramnios + bilateral hydronephrosis (obstructive uropathy). Genetic testing (amnio, CVS) if syndromic.
3
Fetal intervention candidacy – Gestational age (usually 22-30 wks), presence of progressive organ damage, maternal safety, severe prognosis without therapy.
4
Delivery planning – EXIT procedure for CHAOS, giant neck masses, or large lung lesions. Delivery at level IV NICU with pediatric surgery/neonatology.
5
Postnatal confirmation – Chest X-ray for CDH, MRI brain for MMC, echocardiogram, surgical repair after stabilization (CDH, MMC).

📋 Stepwise management of surgically correctable fetal conditions

1
Obstructive uropathy – Confirm fetal urine electrolytes (Na <100, Cl <90, osm >210). Vesicoamniotic shunt or fetoscopic valve ablation. Goal: restore amniotic fluid.
2
Severe CDH (LHR <25%) – FETO balloon placement ~28 wk, removal ~34 wk. Postnatal gentle ventilation, ECMO if needed, surgical repair after stabilization.
3
Macrocystic CPAM with hydrops – Maternal betamethasone, thoracoamniotic shunt, or open fetal resection if gestational age <32 weeks. EXIT if near term.
4
Myelomeningocele (MMC) – Prenatal open repair <26 weeks (MOMS criteria) reduces need for VP shunt. Fetoscopic repair experimental.
5
TTTS stage II–IV – Fetoscopic laser photocoagulation of anastomoses (Solomon technique) before 26 weeks. Amnioreduction for palliation only if laser not feasible.
6
SCT with cardiac compromise – RFA or laser ablation of tumor vessels, fetal debulking if hydrops develops. Early C-section.
📌 Key outcome predictors: O/E TLV for CDH, CVR for CPAM, presence of hydrops, gestational age at intervention, center experience.

🧠 Rapid reflex prompts – Fetal surgery & counseling

📌 First-line for severe left CDH?
FETO (fetoscopic tracheal occlusion) if O/E LHR <25% after 27-29 weeks.
📌 Best evidence for prenatal MMC repair?
MOMS trial: decreased VP shunt (40% vs 82%), improved motor outcomes at 30 mo.
📌 Emergency EXIT indication?
CHAOS (laryngeal atresia) or giant cervical teratoma – secure airway on placental support.
📌 Quintero stage III TTTS?
Absent or reversed end-diastolic flow in umbilical artery or ductus venosus; laser therapy indicated.
📌 Prenatal marker of good renal function in obstructive uropathy?
Fetal urine sodium <100 mEq/L, chloride <90, osmolality >210 mOsm/L at ~24 weeks.
📌 Cause of hydrops in large CPAM?
Mediastinal shift → impaired venous return and cardiac compression → high-output failure.