Ultrasound Report Explained - Mrs. Priyanka Ninama (33 Weeks 1 Day)

Basic Details

Fetal Measurements (Biometry)

Other Findings

• Posterior: the placenta is on the back wall of the uterus - a normal location.
• Grade III: indicates a mature placenta. Grade III at 33 weeks is slightly early (usually expected at 36+ weeks), but in combination with the other findings (especially polyhydramnios), the obstetrician needs to be informed.

• AFI (Amniotic Fluid Index) of 22.11 cm is elevated (normal range: 8-18 cm; above 20-25 cm is considered polyhydramnios).
• Polyhydramnios can occur when the fetus is not swallowing amniotic fluid normally - which is strongly linked to the next finding (CDH), as a baby whose stomach/bowel is displaced into the chest may have difficulty swallowing.

The Most Important Finding: Suspected Congenital Diaphragmatic Hernia (CDH)

"Fetus stomach, bowel loops or herniated content seen in thoracic region - Diaphragmatic hernia"

• Incidence: approximately 1 in 3,000 to 5,000 live births
• Left-sided herniation is most common (about 90% of cases)
• It is frequently first detected on a routine obstetric ultrasound, exactly as in this case

1. Pulmonary hypoplasia (underdeveloped lungs) - the herniated gut compresses and retards maturation of both lungs, especially the same-side lung
2. Pulmonary hypertension (high blood pressure in the lungs) after birth
3. Ventricular dysfunction - stress on the heart

What Happens Next - Immediate Steps Required

1. Referral to a Fetal Medicine Unit / Tertiary Centre - This is the most important step. CDH requires management by a multidisciplinary team including maternal-fetal medicine specialists, neonatologists, and pediatric surgeons.
2. Detailed Anomaly Scan - A targeted scan by a fetal medicine specialist to confirm the diagnosis, assess which organs are herniated (stomach, bowel, liver), and measure the lung-to-head ratio (LHR) or observed/expected LHR - this predicts lung development and prognosis.
3. Fetal MRI - May be recommended to better assess the extent of herniation and estimate fetal lung volumes. A 2026 systematic review (PMID: 41319474) confirms prenatal ultrasound and MRI are the key tools for predicting survival in severe CDH.
4. Chromosomal/Genetic Testing - CDH can be associated with chromosomal abnormalities (e.g., Trisomy 18, 21); genetic counselling may be advised.
5. Echocardiography (fetal echo) - To assess cardiac anatomy (CDH is associated with congenital heart defects) and early signs of pulmonary hypertension.
6. Delivery Planning - Delivery should be planned at a tertiary centre with a Level III NICU and pediatric surgical capability. The baby will likely need immediate intubation and respiratory support at birth.
7. Postnatal surgical repair - The defect is repaired surgically, but not immediately at birth. The current approach is to stabilize the newborn first (sometimes using ECMO if needed), and only perform surgery once the baby is hemodynamically stable. As noted in Mulholland & Greenfield's Surgery: "CDH is a physiologic emergency and not a surgical emergency."

Summary for the Family

• Baby's growth is normal for 33 weeks.
• The scan has found a serious condition where the baby's stomach and bowel appear to be inside the chest cavity instead of the abdomen. This is called Congenital Diaphragmatic Hernia.
• This is not something that can be fixed before birth in most settings.
• The baby will need specialized care immediately after delivery, including a breathing tube, possible surgery, and intensive care.
• The family should be referred urgently to a tertiary hospital with a Neonatal Intensive Care Unit (NICU) and pediatric surgical team so that delivery can be planned and the baby receives the best possible care from the moment of birth.
• The other aspects of the scan (growth, heartbeat, cervix) are reassuring, but this finding needs prompt specialist attention.

Management of Congenital Diaphragmatic Hernia (CDH)

PHASE 1 - Antenatal Management (Now, at 33 Weeks)

1. Urgent Referral to a Tertiary/Fetal Medicine Centre

2. Confirm and Characterize the Diagnosis

• O/E LHR < 25% = severe CDH, ~15% survival without intervention
• O/E LHR 25-35% = moderate CDH
• O/E LHR > 45% = mild CDH, survival approaches 80-90%

3. Prenatal Intervention - FETO (Fetoscopic Endoluminal Tracheal Occlusion)

4. Multidisciplinary Counselling

5. Delivery Planning

• Delivery should occur at the tertiary centre (do NOT deliver at a peripheral hospital)
• Timing: CDH itself is not an indication for preterm delivery; aim for term unless obstetric indications arise
• Mode: Vaginal delivery is generally acceptable; caesarean section only for obstetric indications
• A neonatal resuscitation team (neonatologist, pediatric surgeon, NICU) must be present at delivery

PHASE 2 - Neonatal Stabilization (Immediately After Birth)

Immediate Resuscitation

• Immediate intubation at delivery - do NOT attempt bag-mask ventilation (risks gastric distension and further lung compression)
• Insert a nasogastric tube for gastric decompression
• Avoid nitrous oxide (causes bowel gas expansion)
• Limit peak inspiratory pressure < 25 cmH₂O to prevent barotrauma
• Target preductal SpO₂ 85-95%; accept mild hypoxemia rather than over-ventilate

Ventilatory Strategy - "Gentle Ventilation" (Gentilation)

• Permissive hypercapnia: allow PaCO₂ up to 60-65 mmHg (post-ductal)
• Pressure-limited ventilation with low tidal volumes
• High-Frequency Oscillatory Ventilation (HFOV) if conventional ventilation fails - provides better gas exchange with less barotrauma
• Avoid aggressive ventilation that worsens pulmonary hypertension

Treatment of Pulmonary Hypertension

ECMO (Extracorporeal Membrane Oxygenation)

• Venoarterial (VA) ECMO preferred for combined cardiac and respiratory failure
• Allows the lungs to "rest" while maintaining systemic perfusion
• Bridging therapy until the baby is stable enough for surgery
• As noted in Miller's Anesthesia: "Unstable neonates with CDH may require ECMO and inhaled nitric oxide" before surgery can be planned

PHASE 3 - Surgical Repair

Timing

• Not an emergency - delay surgery until hemodynamic stability is achieved
• In stable infants: defer repair 48-72 hours after birth to allow pulmonary vascular lability to settle (Sabiston)
• In ECMO-dependent infants: timing is debated; some favour repair during ECMO, others after decannulation (bleeding risk is higher on ECMO)

Surgical Approach

1. Reduce herniated viscera back into the abdomen
2. Excise hernia sac (if present)
3. Identify and mobilize diaphragm leaflets
4. Close the diaphragmatic defect

• Primary repair with interrupted non-absorbable sutures - preferred when possible
• Patch repair (Gore-Tex / Surgisis) for large defects where primary closure would be under tension - patch repairs have higher recurrence rates but are necessary for large defects

PHASE 4 - Long-Term Follow-Up

Summary Flowchart for This Case

33-week scan → CDH suspected
        ↓
URGENT referral to tertiary centre
        ↓
Detailed US + MRI + Fetal echo + Genetics
        ↓
FETO: NOT possible at 33 wks (window 27-29 wks)
        ↓
Plan delivery at tertiary centre (with NICU + peds surgery)
        ↓
At birth: Immediate intubation + NG tube
        ↓
Gentle ventilation + treat pulmonary hypertension
        ↓
If fails → ECMO
        ↓
Stabilise 48-72 hrs → Surgical repair
        ↓
Long-term NICU + multidisciplinary follow-up