Overview
Definition
- Abnormal connection between the abdominal and chest cavities through a diaphragmatic defect
- Arises due to the pleuroperitoneal folds failing to fuse during embryonic development
Epidemiology
- Incidence: 1 in 10,000 live births
- No association with gender or ethnicity
- Most commonly sporadic with rare familial incidence
- Associated anomalies occur in about 30% of congenital diaphragmatic hernia (CDH) cases and include:
- Lesions of the central nervous system (CNS) and cardiovascular systems
- Omphalocele
- Esophageal atresia
- Associated chromosomal syndromes include:
- Trisomies 13, 18, and 21
- Turner syndrome
- The majority of CDH are Bochdalek hernias (up to 90%).
- Morgagni hernias account for only 2%–6% of cases.
Embryology
Multiple embryological mechanisms have been proposed:
- Failure of diaphragmatic structure fusion
- The diaphragm is composed of 4 embryological structures:
- 2 pleuroperitoneal membranes
- Septum transversum
- Muscular ingrowth from the body wall
- Failure of these structures to fuse during the 4th to 10th weeks of gestation leaves residual openings that can become hernias.
- The diaphragm is composed of 4 embryological structures:
- Premature involution and malrotation of the midgut
- 6th week of gestation: The midgut grows rapidly, extending outside the embryo.
- 9th week of gestation: Midgut twists and re-enters the embryo’s abdomen.
- Premature re-entry or incorrect rotation of the bowel → higher pressure in the abdominal cavity than the chest cavity → failure of the correct formation of the diaphragm
- Pulmonary hypoplasia
- Failure of the lungs to develop appropriately → decreased pressure in the chest cavity
- Causes a pressure differential that pushes on the diaphragm
- The diaphragm does not fuse appropriately.
Embryological development of the diaphragm morphogenesis depicted at 5 weeks (A) and 4 months (B) of gestation.
Image: “Diaphragm morphogenesis” by Division of Pediatric Surgery, Morgan Stanley Children’s Hospital of New York-Presbyterian and Department of Surgery, College of Physicians and Surgeons, Columbia University, 3959 Broadway, 216B, New York, NY 10032, USA. License: CC BY 2.0
The diaphragm is described as arising from the septum transversum, pleuroperitoneal folds (PPFs), esophageal mesentery, and thoracic body wall.
Diagram showing intestinal rotation and herniation during normal embryonic development. From panel A to B, the midgut loop rotates 90° in a counterclockwise direction, so that its position changes from midsagittal (A) to transverse (B1).
Image: “Intestine normal development” by Soffers, J.H., Hikspoors, J.P., Mekonen, H.K. et al. License: CC BY 4.0
The small intestine forms loops (B2) and slides back into the abdomen (B3) during resolution of the hernia. Meanwhile, the cecum moves from the left to the right side, which represents the additional 180° counterclockwise rotation of the intestine (C, central view).
Classification
- Bochdalek hernia:
- Constitutes 90% of congenital diaphragmatic hernias
- Defect in the posterolateral portion of the diaphragm
- More commonly left-sided with some occurring bilaterally
- Morgagni hernia:
- Retrosternal resulting from failure of sternal and crural portions to meet
- More commonly right-sided
- The majority of Morgagni hernias are asymptomatic and discovered incidentally on imaging.
- Hiatal hernia: through the esophageal hiatus
- Paraesophageal hernia: area adjacent to esophageal hiatus
Classification of CDH based on the location of diaphragmatic hernias.
Image by Lecturio.
The most common type is the posterior lateral hernia (approximately 90%), also known as Bochdalek hernia. Most of these hernias occur on the left side (85%).
Other types of hernias are the anterior defect or Morgagni hernia (2%–6%), followed by the rare central hernia (2%).
A: Normal anatomy
Image: “Hiatus hernia” by Mysid. License: Public Domain, edited by Lecturio.
B: Pre-stage
C: Sliding hiatus hernia
D: Paraesophageal hiatus hernia
Pathophysiology
Pathological effects of CDH are due to lung hypoplasia:
- Lack of space and increased pressure inhibit lung maturation.
- Decreased bronchial and arterial pulmonary branching
- Reduced surface area for gas exchange
- Arterial smooth muscle hyperplasia leading to pulmonary hypertension
Clinical Presentation and Diagnosis
Prenatal diagnosis
- Patients may be diagnosed on routine screening prenatal ultrasound at 16–24 weeks’ gestation.
- Prenatal diagnosis allows for:
- Family counseling
- Possible fetal interventions
- Postnatal planning including referral to a specialized center
- Prenatal ultrasound findings include:
- Lung-to-head ratio index (a number below one signifies severe CDH)
- Gastric bubble or liver in the thorax
- Polyhydramnios
- Chest mass with or without mediastinal shift
Ultrasonography: Congenital diaphragmatic hernia. The heart (arrow) is pushed to the right within the thorax and the stomach (STM) is seen in the thorax.
Image: “Congenital diaphragmatic hernia” by US National Library of Medicine. License: CC BY 2.0Early postnatal presentation
- Respiratory distress is the most common presenting sign.
- Tachypnea, grunting, cyanosis
- Can develop immediately or up to 2 days after birth
- Characteristic exam findings include:
- General: craniofacial syndromic findings often noted before signs of CDH
- Chest:
- Increased diameter (barrel chest) and asymmetry
- Decreased breath sounds ± bowel sounds ± displaced maximal cardiac impulse
- Abdomen: scaphoid deformity
- Imaging:
- To be performed to confirm CDH immediately postnatally
- Chest X-ray shows tip of the nasogastric tube in the chest.
- Chest computed tomography (CT) scan may be used for further delineation of the defect.
Chest radiograph showing left diaphragmatic hernia and contralateral shift of the heart and mediastinum
Image: “Chest radiograph” by Alberta Children’s Hospital, Calgary, AB, Canada T3B 6A8. License: CC BY 4.0
Axial CT scan of the chest: Gas-filled large bowel loops are visible behind the heart, lying anteriorly to the spine and the aorta.
Image: “Axial CT scan of the chest” by Department of Anatomical, Histological, Forensic and Locomotor System Sciences, V, A, Borelli 50, Rome, 00161, Italy. License: CC BY 2.0
Computed tomography scan of the chest. Coronal reconstruction. Part of the stomach, adjacent to the heart (A), is clearly visible. Some bowel loops (B) are also visible on the left side of the chest: the left lung is displaced and compressed.
Image: “Computed tomography scan of the chest” by 2013 Bianchi et al., BioMed Central Ltd. License: CC BY 2.0
Delayed presentation
- May present after the neonatal period
- Vomiting with mild respiratory symptoms
- Sepsis and shock may occur due to incarceration of the bowel through the defect.
- May be a rare cause of sudden death in infants and toddlers
Congenital diaphragmatic hernia in a fetus at 35 weeks’ gestation, including intestines and spleen on, coronal (A) and sagittal images (B), and postnatal chest X-ray (C)
Image: “Congenital diaphragmatic hernia in the 35th GW fetus” by Department of Radiology, School of Medicine, Acibadem University, Istanbul, Turkey. License: CC BY 3.0Management
Prenatal management
- Close monitoring
- Monthly ultrasounds to assess fetal well-being and amniotic fluid levels
- Weekly biophysical profiles in the 3rd trimester
- Amniotic fluid reduction
- Reduced fetal ability to swallow amniotic fluid may lead to polyhydramnios.
- Amnioreduction may be indicated.
- Fetal surgeries
- Reserved for fetuses with a CDH with poor prognosis
- High rate of failure
- 2 options:
- Patch closure of the diaphragmatic defect in utero
- Fetal endoscopic tracheal occlusion (FETO)
Perinatal management
- Choice of timing and location of birth
- As close to term as possible (> 39 weeks preferred)
- In a medical center capable of extracorporeal membrane oxygenation (ECMO)
- Post-natal resuscitation:
- Aggressive respiratory support with endotracheal intubation
- Avoidance of prolonged mask ventilation due to increase in intestinal air with further respiratory compromise
- High-frequency oscillatory ventilation (HFOV), a low-pressure ventilation mode, may be indicated to prevent lung injury.
- ECMO may be used in children who fail to respond to conventional ventilation and/or HFOV.
- Surgery:
- Bochdalek hernia: surgical repair recommended 48 hours after stabilization
- Asymptomatic Morgagni hernia: laparoscopic repair recommended due to risk of future strangulation
- Paraesophageal hernia: Prompt repair is recommended.
A: Plain X-ray of the thorax of a newborn with CDH. There are bowel loops into the left hemithorax, the mediastinum is displaced to the contralateral side, and the space occupied by the lung is reduced.
Image: “Plain X-ray” by Universidad Autonoma de Madrid, Department of Pediatric Surgery, Hospital Universitario La Paz, Madrid, Spain. License: CC BY 2.0
B and C: At laparotomy, a left posterolateral diaphragmatic hernia was discovered.
In B, small bowel loops can be seen entering the thorax through the orifice.
In C, this is seen after reducing the contents of the hernia.
D: The patient died of severe persistent pulmonary hypertension days later. At autopsy, extreme left lung hypoplasia and less severe right lung hypoplasia were discovered.
A: Left-sided diaphragmatic hernia showing the hypoplastic left lung, inferior muscle edge of the diaphragm, and reduced viscera
Image: “Left sided diaphragmatic hernia” by US National Library of Medicine. License: CC BY 4.0
B: Prosthetic patch (Gore-Tex patch) used to close the defect
Paraesophageal hernia repair: complete sac excision and mobilization of an adequate segment of intra-abdominal esophagus
Image: “Complete sac excision” by Department of Surgery, Brigham and Women’s Hospital, Boston VA Health Care System, Boston, MA , USA. License: CC BY 4.0
Prognosis
- Indicators of poor prognosis include:
- Associated major anomalies
- Presentation in 1st 24 hours of life
- Severe lung hypoplasia
- Herniation to contralateral thorax
- Need for ECMO
- Long-term morbidity includes:
- Obstructive and/or restrictive pulmonary defects
- Gastroesophageal reflux disease
- Delayed growth in the 1st 2 years of life
- Neurocognitive deficits (especially in those receiving ECMO)
Differential Diagnosis
- Congenital pulmonary airway malformations (CPAM): rare congenital airway malformations, often cystic in nature. These intrapulmonary structures prevent normal lung tissue expansion predisposing it to infections and malignancy. Like CDH, they can present with tachypnea in a neonate.
- Eventration of the diaphragm: failure of the muscle tissue to cover the diaphragm during fetal development. This leaves only a thin fibrous layer which can then become elevated, protruding into the chest cavity. Eventration of the diaphragm can present like CDH but without true communication between the abdominal and chest cavity.
- Oligohydramnios: insufficient amniotic fluid due to low production (renal dysfunction) or chronic loss during pregnancy, leading to hypoplastic lungs. These patients present with tachypnea and cyanosis, as in CDH, but have no detectable masses in their chest cavity.
References
- Deprest J et al. (2014). Prenatal management of the fetus with isolated congenital diaphragmatic hernia in the era of the TOTAL trial. Semin Fetal Neonatal Med.
- McGivern MR et al. (2015). Epidemiology of congenital diaphragmatic hernia in Europe: a register-based study. Arch Dis Child Fetal Neonatal Ed. doi: 10.1136/archdischild-2014-30617
