Diaphragmatic hernia

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Diaphragmatic hernia Main page
Patient Information
Overview
Historical Perspective
Classification
Pathophysiology
Differentiating Diaphragmatic hernia from other Diseases
Epidemiology
Risk factors
Screening
Natural History, Complications and Prognosis
Diagnosis
History and Symptoms
Physical Examination
Laboratory Findings
Radiological tests
Treatment
Medical treatment
Surgical treatment

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1];Associate Editor(s)-in-Chief: Ahmed Younes M.B.B.CH [2] Mohammed Abdelwahed M.D[3]

Synonyms and keywords: Congenital diaphragm hernia, Diaphragm hernia, Hernia through the diaphragm.

Overview

Diaphragmatic hernia is a congenital anomaly that occurs due to failure of the diaphragm to close leading to herniation of the abdominal content into the thoracic cavity leading to pulmonary hypoplasia. It most commonly presents in the neonates as respiratory distress. It is classified according to the site of herniation into anterior, posterolateral, and hiatal diaphragmatic hernia. It can cause complications in both the GIT and the cardiopulmonary circulation. It can be diagnosed antenatally in the week 24 and after birth, it is apparent on chest x-ray. The mainstay of treatment is surgical correction which must be done when the infant is completely stabilized.

Historical Perspective

• In 1679, the first case of congenital diaphragmatic hernia was reported by Riverius.
• In 1888, the first procedure to repair congenital diaphragmatic hernia in an adult was done and in 1889, the first procedure on an infant was done.
• In 1905, the first successful operation was done but the success rate remained below 60% until 1925.
• In 1940, A set of diagnostic criteria for diaphragmatic hernia were suggested.
• In 1950, the transthoracic approach was suggested instead of the transabdominal approach.

Classification

Congenital diaphragmatic hernia can be classified into three types according to the site of herniation.

Posterolateral (Bochdalek) diaphragmatic hernia

• It is the most common subtype.
• Most commonly occurs on the left side and rarely occurs bilaterally.

Anterior (Morgagni) diaphragmatic hernia

• In anterior diaphragmatic hernia, the intestine bulges into the thorax through the anterior midline.
• Most of the cases of anterior diaphragmatic hernia occur on the right side.

Hiatal hernia

• The intestine finds its way to the thorax through the esophageal hiatus.
• More common in the adults than in neonates.

Pathophysiology and embryogenesis

• Hernia starts during the lung development, from the third week to the 16^th week of gestation. Interference with lung development leads to pulmonary hypoplasia and hypoplasia of cardiac structures.
• It is due to failure of normal closure of the pleuroperitoneal folds during the 4^th to 10^th weeks.
• The vast majority of congenital diaphragmatic hernias occurs sporadically. However, familial cases involving autosomal recessive, autosomal dominant, and X-linked inheritance patterns have been reported.
• Many different genetic defects (eg, aneuploidies, deletions, duplications, translocations) have been identified among sporadic cases.

• The herniated viscera decrease the area needed by the lung to develop appropriately.
• According to the degree of herniation, the degree of pulmonary hypoplasia is determined.
• The herniated viscera impairs the development of the bronchial tree.
• As a consequence, the alveoli development is also slowed.
• The development of the pulmonary artery tree is halted too resulting in excessive masculinization of the arteries.
• The increased pulmonary pressure leads to increased pressure on the right ventricle leading to the development of a right to left shunt.
• As most of the cases of diaphragmatic hernias are unilateral, the pulmonary hypoplasia is also usually unilateral, but it can be bilateral if the mediastinum is pushed by a massive unilateral hernia.
• The abnormal alveolar development can lead to hypoxemia leading to pulmonary vasoconstriction which aggravates the condition.

Risk factors

Risk factors of diaphragmatic hernia include:

• Male gender
• Premature birth
• Macrosomia
• Low birth weight
• Vitamin A deficiency
• Exposure to thalidomide
• Exposure to anticonvulsants and quinine

Differentiating Diaphragmatic hernia from other Diseases

Congenital diaphragmatic hernia may be differentiated from other thoracic lesions:

• Congenital cystic adenomatoid malformation
• Bronchopulmonary sequestration
• Bronchopulmonary foregut malformation
• Bronchogenic cysts
• Bronchial atresia
• Enteric cysts
• Teratomas

Congenital diaphragmatic hernia may be differentiated from other causes of pulmonary hypertension:

• Neonatal pneumonia
• Transient tachypnea of the newborn
• Respiratory distress syndrome
• Sepsis

Epidemiology

Incidence

• The incidence of congenital diaphragmatic hernia ranges from 50-150 per 100.000 live births.

Prevalence

• The prevalence of congenital diaphragmatic hernia ranges from 10 to 40 per live births.

Sex

• Congenital diaphragmatic hernia has no sex predilection.

Age

• 90% of the congenital diaphragmatic hernias present in the neonatal period.

Screening

• According to USPSTF, there is no screening recommended for diaphragmatic hernia. The recurrence risk for multiple congenital anomalies of unknown etiology is considered to be <5 percent. [41]
• Referral to a genetic counselor can be useful for thorough genetic evaluation and counseling.
• Microarray-based comparative genomic hybridization is a powerful tool for detection of submicroscopic chromosomal abnormalities.

Natural history, complications and prognosis

Natural history

• 90% of the cases of congenital diaphragmatic hernia presents in the neonatal period.
• If left untreated, congenital diaphragmatic hernia can be fatal due to pulmonary hypoplasia and severe pulmonary hypertension.

Complications

GI complications

• Abnormal developmental rotation of the midgut
• Midgut volvulus
• Gastric volvulus

Cardiopulmonary complications

• Pulmonary hypoplasia
• Pulmonary artery hypertension
• In severe cases, ventricular hypoplasia

Prognosis

• The prognosis is mainly dependent on the size of the defect and the degree of the herniation.
• The presence or absence of liver herniation on fetal MRI is the most reliable prediction of the postnatal survival.
• The estimation of fetal lung volume and lung area to head circumference is a useful indicator of the prognosis of the disease in the absence of liver herniation.
• The mortality ranges from 25-60% of the cases.

History and Symptoms

CDH most often presents in the neonatal period as:

• Cyanosis
• Rapid breathing (tachypnea)
• Shortness of breath (dyspnea)
• Increased work of breathing (labored breathing)
• Lethargy
• Intolerance to feeding due to inadequate oxygenation.
• Adrenal insufficiency: it is a common association with congenital diaphragmatic hernia.

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Physical Examination

General appearance

• A neonate with CDH usually appears cyanotic and in acute distress.

Vital signs

• Heart rate: tachycardia
• Respiratory rate: tachypnea
• Blood pressure: The infant may have hypotension due to compression of the ventricles

Lungs

• The chest may have a barrel shape.
• Absent breath sounds at the side of the hernia
• Peristaltic sounds in the chest

Heart

• The heart sounds may be displaced to the other side of the chest.
• The heart sounds may reveal the murmurs of associated cardiac anomalies.

Abdomen

• The abdomen is scaphoid due to herniation of the abdominal content into the thoracic cavity.

Laboratory Findings

Antenatal tests

• Amniocentesis: karyotyping should be obtained to rule out associated chromosomal abnormalities.
• Maternal alpha-fetoprotein is decreased in CDH

Postnatal tests

• Arterial blood gas: ABG may show hypoxemia, metabolic acidosis, and hypercapnia.
• The infant should be investigated for the presence of associated chromosomal abnormalities.

Radiological tests

Antenatal ultrasound

• CDH can be diagnosed in the 24th week.
• In addition to the hernia, ultrasound can show polyhydramnios and absence of the gastric air bubble
• Left sided CDH is far more common than right sided CDH, while bilateral CDH is rare.
• The presence of liver herniation is associated with worse prognosis and survival.
• The estimation of lung area to head circumference ratio can give an idea about the prognosis (especially if there is no liver herniation). The lower the ratio, the worse the prognosis.

Coronal ultrasound showing herniation of the abdominal content into the thorax and displacement of the herat to the right - Case courtesy of Dr Laughlin Dawes , Radiopaedia.org, rID: 36006

Chest x-ray

• Bowel loops in the thoracic cavity (can be further demonstrated through placement of a feeding tube)
• Shifting of the mediastinum to the contralateral side

Anteroposterior x-ray showing herniation of the intestine into the thorax and shifting of the mediastinum to the right - Case courtesy of Dr Mohd Imran, Radiopaedia.org, rID: 7392

Echocardiography

• Echocardiography must be done to exclude associated cardiac anomalies and to exclude the presence of an associated ventricular strain from the pressure.

Medical treatment

Criteria for mechanical ventilation:

• Pressure-limited ventilation at rates of 30 to 70 breaths per minute
• Positive end-expiratory pressure (PEEP) should be maintained at physiologic levels (3 to 5 cm H₂O) whenever possible.
• High-frequency ventilation (HFV) is reserved for neonates who continue to have hypoxia and hypercarbia (PaCO₂ >65 mmHg) refractory to CMV.

Antenatal glucocorticoids

Antenatal glucocorticoids improve the survival by increasing the secretion of surfactant and thus stimulating lung maturation and preventing severe pulmonary hypoplasia.

Preoperative stabilization

• Preoperative stabilization of the patient is important as performing the operation in an unstable infant is associated with higher morbidity and mortality rates.

Preoperative stabilization measures include:

• Mechanical ventilation: The aim is to ensure proper oxygenation without causing any barotrauma to the lung. Peak inspiratory pressure should be always less than 30 cm H2O
• Nasogastric tube insertion: The aim is to decompress the bowel and to give more space for the lung
• Blood pressure support: using vasopressors or isotonic fluid: The aim is to keep the mean blood pressure above 50 mmHg.
• High-frequency oscillatory ventilation: It is useful in improving the oxygenation without increasing the pressure in the airways or the alveoli.
• Inhaled nitric oxide: The hypoxemia resulting from lung compression can cause hypoxemia that may result in pulmonary vasoconstriction and hypertension.
• Vasodilator agents such as sildenafil and bosentan are used for severe and persistent pulmonary hypertension in the management of CDH

Extracorporeal membrane oxygenation (ECMO): It is used as the last resort in patients resistant to all the conventional methods of ventilation.

Indications for ECMO:

• Inability to maintain preductal PaO₂ saturations >85 percent or postductal PaO₂ >30 mmHg
• PIP >28 cm H₂O or mean airway pressure (MAP) >15 cm H₂O
• Hypotension that is resistant to fluid and inotropic support
• Inadequate oxygen delivery with persistent metabolic acidosis

Inclusion criteria for ECMO, including in our center, also include all of the following:

• Birth weight (BW) >2 kg
• Gestational age (GA) >34 weeks
• Absence of intracranial hemorrhage greater than grade I
• Absence of chromosomal anomalies

Surgical treatment

• The procedure must not be done unless the infant is stable.
• Most of the operations are done through a subcostal incision.
• The repair can be done in one of two ways depending on its size:
  • Primary closure: it involves repairing the defect using non-absorbable sutures. It is used if the defect is relatively small.
  • Patch closure: using a prosthetic or fascial patch to close the defect. It is useful especially with large defects but increases the risk of infection.
• Endoscopic procedures through the thorax or the abdomen have been reported to have lower mortality rates but have higher recurrence rates.
• If CDH repair is associated with an abdominal wall defect, silo closure may be tried temporarily until the CDH is stabilized.

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