Chapter 31: Congenital Diaphragmatic Hernia

I. Intensive care

1. Definition

   Presence of abdominal contents in thoracic cavity during fetal life results in acute neonatal respiratory distress.

   1. Often the sickest infants in the NICU

   2. Associated with long-term respiratory, gastrointestinal, and neuro-cognitive difficulties

2. Incidence

   Estimated to occur in one per 3000 live births (true incidence unknown)

   1. “Hidden mortality”—early deaths among severely affected fetuses and infants

3. Pathophysiology

   Abnormal or incomplete formation of diaphragm between weeks 8 and 10 of gestation allows herniation of abdominal contents into chest cavity, impairing proper lung growth and development (Figure 31-1).

   1. Occurs at critical stage of lung embryogenesis, during pulmonary artery and bronchial branching

   2. Subsequent pulmonary parenchymal and vascular hypoplasia with fewer airways, vessels, and alveolar structures

   3. Lung hypoplasia most significant on ipsilateral side, contralateral lung also affected

      Epidemiology: Three CDH subtypes based on location of diaphragmatic defect

      1. Bochdalek: posterolateral diaphragmatic defect (most common)

      2. Morgagni: anterior diaphragmatic defect

      3. Pars sternalis: central diaphragmatic defect

         Additional facts about CDH

   1. 85% occur on left side, 13% occur on right, 2% bilateral absence of diaphragm (universally fatal)

   2. Right-sided defects associated with higher mortality due to presence of liver in chest

   3. Can be isolated finding (50% to 60%) or occur as part of syndrome

      • ∼1/3 associated with cardiac, renal, gastrointestinal, or central nervous system anomalies

   4. Overall survival ranges between 50% and 80% for isolated CDH

      • Lower survival rates if other anomalies present

4. Risk factors

   None proven, many postulated

   1. Genetic factors

   2. Maternal nutritional deficiency during pregnancy

   3. Disturbances in retinoid-signaling pathway during organogenesis

5. Clinical presentation

   1. Signs and symptoms

      1. Most present with respiratory distress and cyanosis soon after birth.

         • Intestines dilate with swallowed air and compromise cardiorespiratory function.

      2. Physical examination: Scaphoid abdomen, barrel-shaped chest, increased work of breathing.

      3. Auscultation: Decreased aeration over ipsilateral chest, displacement of heart tones, bowel sounds appreciated in chest.

      4. Imaging: Radiography shows gas-filled loops of bowel in chest, displacement of heart, and mediastinum to right (left-sided) (Figure 31-2).

   2. Condition variability

      Severity of respiratory distress corresponds to degree of pulmonary hypoplasia (related to timing and degree of compression of fetal lungs).

      1. Mild: May not present until later in newborn course or early infancy

      2. Severe or unrecognized: Swallowed air following delivery results in intestinal distention, leads to worsening mediastinal shift, compromised venous return, hypoperfusion, and systemic hypotension

6. Diagnosis

   1. Prenatal: Most cases identified antenatally between 16 and 24 weeks' gestation.

      1. Characteristic findings on ultrasound

         • Fluid-filled stomach detected in chest cavity

         • Polyhydramnios

         • Small abdominal circumference

         • Mediastinal or cardiac shift away from side of hernia

   2. Postnatal: Chest radiography shows multiple gas-filled loops of bowel in thorax (Figure 31-2).

7. Management

   Antenatal

   1. Medical

      1. Detailed anatomic ultrasonography to detect other anomalies

      2. Amniocentesis for chromosomal studies

      3. Determination of liver position and lung-to-head ratio to assess degree of pulmonary hypoplasia and predict outcome

      4. Parental counseling

      5. Expectant management, close monitoring for development of complications

      6. Induction of labor ∼38 weeks' gestation at tertiary care center

   2. Surgical

      1. Many trials of fetal surgery to correct diaphragmatic defect and promote fetal lung growth

      2. Disappointing results due to increased rates ...