Pulmonary Hypoplasia

Overview

Definition

Pulmonary hypoplasia Hypoplasia Hypoplastic Left Heart Syndrome (HLHS) is the insufficient or defective development of one or both lungs Lungs Lungs are the main organs of the respiratory system. Lungs are paired viscera located in the thoracic cavity and are composed of spongy tissue. The primary function of the lungs is to oxygenate blood and eliminate CO2. Lungs: Anatomy, resulting in underdeveloped or undeveloped pulmonary parenchyma with decreased alveoli Alveoli Small polyhedral outpouchings along the walls of the alveolar sacs, alveolar ducts and terminal bronchioles through the walls of which gas exchange between alveolar air and pulmonary capillary blood takes place. Acute Respiratory Distress Syndrome (ARDS) and airway Airway ABCDE Assessment branches.

• Classified as:
  • Type I ( agenesis Agenesis Teratogenic Birth Defects): complete absence of lung parenchyma, bronchus, and vessels
  • Type II ( aplasia Aplasia Cranial Nerve Palsies): the complete absence of pulmonary parenchyma with rudimentary bronchus
  • Type III ( hypoplasia Hypoplasia Hypoplastic Left Heart Syndrome (HLHS)): some degree of pulmonary parenchymal development with decreased number of airways and alveoli Alveoli Small polyhedral outpouchings along the walls of the alveolar sacs, alveolar ducts and terminal bronchioles through the walls of which gas exchange between alveolar air and pulmonary capillary blood takes place. Acute Respiratory Distress Syndrome (ARDS)
• Severity depends on the underlying cause and its timing in relation to fetal lung development.
• Can be unilateral or bilateral

Epidemiology

• Rare condition overall, with high rate of neonatal mortality Mortality All deaths reported in a given population. Measures of Health Status and chronic morbidity Morbidity The proportion of patients with a particular disease during a given year per given unit of population. Measures of Health Status for survivors
• Exact incidence Incidence The number of new cases of a given disease during a given period in a specified population. It also is used for the rate at which new events occur in a defined population. It is differentiated from prevalence, which refers to all cases in the population at a given time. Measures of Disease Frequency is unknown but estimated to be 1.4 per 1000 births.
• Mortality Mortality All deaths reported in a given population. Measures of Health Status and degree of morbidity Morbidity The proportion of patients with a particular disease during a given year per given unit of population. Measures of Health Status related to gestational age Gestational age The age of the conceptus, beginning from the time of fertilization. In clinical obstetrics, the gestational age is often estimated as the time from the last day of the last menstruation which is about 2 weeks before ovulation and fertilization. Pregnancy: Diagnosis, Physiology, and Care when impacted:
  • Often lethal
  • Mortality Mortality All deaths reported in a given population. Measures of Health Status rate of 47% in the 1st 60 days of life in affected babies born alive
  • Mild to severe respiratory symptoms for children who survive the immediate neonatal period
  • Can be a cause of more mild and chronic respiratory symptoms, sometimes discovered later, even into adulthood

Etiology

• Impairment of lung development, especially before 22 weeks of gestational age Gestational age The age of the conceptus, beginning from the time of fertilization. In clinical obstetrics, the gestational age is often estimated as the time from the last day of the last menstruation which is about 2 weeks before ovulation and fertilization. Pregnancy: Diagnosis, Physiology, and Care
• Causes involve multiple factors: 
  • Genetic
  • Environmental
  • Maternal
  • Nutritional
• Primary hypoplasia Hypoplasia Hypoplastic Left Heart Syndrome (HLHS):
  • Rare and fatal (e.g., congenital Congenital Chorioretinitis acinar dysplasia)
  • Not well understood but are thought to be genetic mutation Mutation Genetic mutations are errors in DNA that can cause protein misfolding and dysfunction. There are various types of mutations, including chromosomal, point, frameshift, and expansion mutations. Types of Mutations in growth and transcription factors Transcription Factors Endogenous substances, usually proteins, which are effective in the initiation, stimulation, or termination of the genetic transcription process. Stages of Transcription, which are key to lung development
• Secondary hypoplasia Hypoplasia Hypoplastic Left Heart Syndrome (HLHS):
  • Majority of cases
  • Due to other fetal developmental abnormalities
  • Conditions that lead to reduced space of the thoracic cavity during fetal development:
    • Congenital diaphragmatic hernia Congenital Diaphragmatic Hernia Pediatric Chest Abnormalities (CDH)
    • Fetal hydrops Hydrops Cholecystitis ( pleural effusion Pleural Effusion Pleural effusion refers to the accumulation of fluid between the layers of the parietal and visceral pleura. Common causes of this condition include infection, malignancy, autoimmune disorders, or volume overload. Clinical manifestations include chest pain, cough, and dyspnea. Pleural Effusion)
    • Mediastinal mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast
    • Congenital Congenital Chorioretinitis cystic Cystic Fibrocystic Change adenomatoid malformations or CCAM (now referred to as congenital Congenital Chorioretinitis pulmonary airway Airway ABCDE Assessment malformation (CPAM))
    • Abdominal tumors
    • Skeletal abnormalities (thoracic dystrophy or Jeune syndrome, skeletal dysplasia, chest wall Chest wall The chest wall consists of skin, fat, muscles, bones, and cartilage. The bony structure of the chest wall is composed of the ribs, sternum, and thoracic vertebrae. The chest wall serves as armor for the vital intrathoracic organs and provides the stability necessary for the movement of the shoulders and arms. Chest Wall: Anatomy tumors)
  • Conditions associated with oligohydramnios Oligohydramnios Oligohydramnios refers to amniotic fluid volume less than expected for the current gestational age. Oligohydramnios is diagnosed by ultrasound and defined as an amniotic fluid index (AFI) of ‰¤ 5 cm or a single deep pocket (SDP) of < 2 cm in the 2nd or 3rd trimester. Oligohydramnios before 28th week of gestation:
    • Renal agenesis Agenesis Teratogenic Birth Defects
    • Urinary outflow tract obstructive lesions
    • Prolonged, preterm membrane rupture
    • Bilateral cystic Cystic Fibrocystic Change kidneys Kidneys The kidneys are a pair of bean-shaped organs located retroperitoneally against the posterior wall of the abdomen on either side of the spine. As part of the urinary tract, the kidneys are responsible for blood filtration and excretion of water-soluble waste in the urine. Kidneys: Anatomy
  • Disorders of impaired breathing:
    • Phrenic nerve Phrenic nerve The motor nerve of the diaphragm. The phrenic nerve fibers originate in the cervical spinal column (mostly C4) and travel through the cervical plexus to the diaphragm. Diaphragm: Anatomy abnormality
    • Neuromuscular or CNS disorders
  • Chromosomal abnormalities:
    • Trisomy 21 Trisomy 21 Down syndrome, or trisomy 21, is the most common chromosomal aberration and the most frequent genetic cause of developmental delay. Both boys and girls are affected and have characteristic craniofacial and musculoskeletal features, as well as multiple medical anomalies involving the cardiac, gastrointestinal, ocular, and auditory systems. Down syndrome (Trisomy 21) ( Down syndrome Down syndrome Down syndrome, or trisomy 21, is the most common chromosomal aberration and the most frequent genetic cause of developmental delay. Both boys and girls are affected and have characteristic craniofacial and musculoskeletal features, as well as multiple medical anomalies involving the cardiac, gastrointestinal, ocular, and auditory systems. Down syndrome (Trisomy 21))
    • Trisomy Trisomy The possession of a third chromosome of any one type in an otherwise diploid cell. Types of Mutations 13 ( Patau syndrome Patau syndrome Trisomy 13, or Patau syndrome, is a genetic syndrome caused by the presence of 3 copies of chromosome 13. As the 3rd most common trisomy, Patau syndrome has an incidence of 1 in 10,000 live births. Most cases of Patau syndrome are diagnosed prenatally by maternal screening and ultrasound. More than half of the pregnancies result in spontaneous abortions. Patau Syndrome (Trisomy 13))
    • Trisomy Trisomy The possession of a third chromosome of any one type in an otherwise diploid cell. Types of Mutations 18 (Edwards’ syndrome)
  • Congenital Congenital Chorioretinitis heart disease with pulmonary blood flow Blood flow Blood flow refers to the movement of a certain volume of blood through the vasculature over a given unit of time (e.g., mL per minute). Vascular Resistance, Flow, and Mean Arterial Pressure impairment:
    • Tetralogy of Fallot Tetralogy of Fallot Tetralogy of Fallot is the most common cyanotic congenital heart disease. The disease is the confluence of 4 pathologic cardiac features: overriding aorta, ventricular septal defect, right ventricular outflow obstruction, and right ventricular hypertrophy. Tetralogy of Fallot
    • Pulmonary artery Pulmonary artery The short wide vessel arising from the conus arteriosus of the right ventricle and conveying unaerated blood to the lungs. Lungs: Anatomy hypoplasia Hypoplasia Hypoplastic Left Heart Syndrome (HLHS)
    • Hypoplastic right heart

Pathophysiology

Fetal lung development

• 4th week of gestation:
  • Laryngotracheal groove forms from the wall of the primitive pharynx Pharynx The pharynx is a component of the digestive system that lies posterior to the nasal cavity, oral cavity, and larynx. The pharynx can be divided into the oropharynx, nasopharynx, and laryngopharynx. Pharyngeal muscles play an integral role in vital processes such as breathing, swallowing, and speaking. Pharynx: Anatomy → the groove elongates, with distal end bifurcating into tracheal buds and then bronchial buds
  • Process of elongation Elongation Polymerase Chain Reaction (PCR) and branching of buds continues as conducting airways up to 16 weeks of gestation.
• From 16 weeks to birth, the gaseous exchange system (acini) develops:
  • 16–26 weeks: canalicular stage Canalicular Stage During this stage, the respiratory units (also referred to as canaliculi) develop at the end of the terminal bronchioles. Development of the Respiratory System
  • 26–40 weeks: terminal sac stage
• Normal development of the fetal lung depends on: 
  • Normal thoracic cavity space
  • Mechanical forces that require adequate amniotic fluid Amniotic fluid A clear, yellowish liquid that envelopes the fetus inside the sac of amnion. In the first trimester, it is likely a transudate of maternal or fetal plasma. In the second trimester, amniotic fluid derives primarily from fetal lung and kidney. Cells or substances in this fluid can be removed for prenatal diagnostic tests (amniocentesis). Placenta, Umbilical Cord, and Amniotic Cavity:
    • Spontaneous contraction of developing airways
    • Fetal breathing movements

Abnormal fetal lung development

Multiple aspects of the impairment of fetal lung growth can lead to hypoplasia Hypoplasia Hypoplastic Left Heart Syndrome (HLHS).

• Oligohydramnios Oligohydramnios Oligohydramnios refers to amniotic fluid volume less than expected for the current gestational age. Oligohydramnios is diagnosed by ultrasound and defined as an amniotic fluid index (AFI) of ‰¤ 5 cm or a single deep pocket (SDP) of < 2 cm in the 2nd or 3rd trimester. Oligohydramnios:
  • Lack of amniotic fluid Amniotic fluid A clear, yellowish liquid that envelopes the fetus inside the sac of amnion. In the first trimester, it is likely a transudate of maternal or fetal plasma. In the second trimester, amniotic fluid derives primarily from fetal lung and kidney. Cells or substances in this fluid can be removed for prenatal diagnostic tests (amniocentesis). Placenta, Umbilical Cord, and Amniotic Cavity → lack of lung distensibility and arterial branching → decreased surface area for gas exchange Gas exchange Human cells are primarily reliant on aerobic metabolism. The respiratory system is involved in pulmonary ventilation and external respiration, while the circulatory system is responsible for transport and internal respiration. Pulmonary ventilation (breathing) represents movement of air into and out of the lungs. External respiration, or gas exchange, is represented by the O2 and CO2 exchange between the lungs and the blood. Gas Exchange
  • Can be secondary to:
    • Premature Premature Childbirth before 37 weeks of pregnancy (259 days from the first day of the mother’s last menstrual period, or 245 days after fertilization). Necrotizing Enterocolitis rupture of membranes at early gestational age Gestational age The age of the conceptus, beginning from the time of fertilization. In clinical obstetrics, the gestational age is often estimated as the time from the last day of the last menstruation which is about 2 weeks before ovulation and fertilization. Pregnancy: Diagnosis, Physiology, and Care
    • Renal dysgenesis or agenesis Agenesis Teratogenic Birth Defects (at 16 weeks of gestational age Gestational age The age of the conceptus, beginning from the time of fertilization. In clinical obstetrics, the gestational age is often estimated as the time from the last day of the last menstruation which is about 2 weeks before ovulation and fertilization. Pregnancy: Diagnosis, Physiology, and Care, fetal urine becomes the main source of amniotic fluid Amniotic fluid A clear, yellowish liquid that envelopes the fetus inside the sac of amnion. In the first trimester, it is likely a transudate of maternal or fetal plasma. In the second trimester, amniotic fluid derives primarily from fetal lung and kidney. Cells or substances in this fluid can be removed for prenatal diagnostic tests (amniocentesis). Placenta, Umbilical Cord, and Amniotic Cavity)
  • Potter sequence potter sequence Potter sequence, which is due to severe oligohydramnios and the compressive effect of enlarged kidneys: positional limb deformities, craniofacial abnormalities, pulmonary hypoplasia, growth impairment, and feeding difficulties. Autosomal Recessive Polycystic Kidney Disease (ARPKD), or Potter syndrome Potter syndrome Potter sequence, which is due to severe oligohydramnios and the compressive effect of enlarged kidneys: positional limb deformities, craniofacial abnormalities, pulmonary hypoplasia, growth impairment, and feeding difficulties. Autosomal Recessive Polycystic Kidney Disease (ARPKD) (historic term), encompasses features resulting from oligohydramnios Oligohydramnios Oligohydramnios refers to amniotic fluid volume less than expected for the current gestational age. Oligohydramnios is diagnosed by ultrasound and defined as an amniotic fluid index (AFI) of ‰¤ 5 cm or a single deep pocket (SDP) of < 2 cm in the 2nd or 3rd trimester. Oligohydramnios and causing mechanical compression Compression Blunt Chest Trauma: 
    • Pulmonary hypoplasia Hypoplasia Hypoplastic Left Heart Syndrome (HLHS)
    • Limb deformities
    • Potter facies (flattened nose Nose The nose is the human body’s primary organ of smell and functions as part of the upper respiratory system. The nose may be best known for inhaling oxygen and exhaling carbon dioxide, but it also contributes to other important functions, such as tasting. The anatomy of the nose can be divided into the external nose and the nasal cavity. Nose Anatomy (External & Internal), recessed chin Chin The anatomical frontal portion of the mandible, also known as the mentum, that contains the line of fusion of the two separate halves of the mandible (symphysis menti). This line of fusion divides inferiorly to enclose a triangular area called the mental protuberance. On each side, inferior to the second premolar tooth, is the mental foramen for the passage of blood vessels and a nerve. Melasma, epicanthal folds, low-set ears Low-set ears DiGeorge Syndrome)
• Reduced thoracic space:
  • Intrathoracic lesions:
    • CPAM
    • Pleural effusion Pleural Effusion Pleural effusion refers to the accumulation of fluid between the layers of the parietal and visceral pleura. Common causes of this condition include infection, malignancy, autoimmune disorders, or volume overload. Clinical manifestations include chest pain, cough, and dyspnea. Pleural Effusion
  • Extrathoracic lesions:
    • CDH
    • Ascites Ascites Ascites is the pathologic accumulation of fluid within the peritoneal cavity that occurs due to an osmotic and/or hydrostatic pressure imbalance secondary to portal hypertension (cirrhosis, heart failure) or non-portal hypertension (hypoalbuminemia, malignancy, infection). Ascites
    • Eventration of diaphragm Diaphragm The diaphragm is a large, dome-shaped muscle that separates the thoracic cavity from the abdominal cavity. The diaphragm consists of muscle fibers and a large central tendon, which is divided into right and left parts. As the primary muscle of inspiration, the diaphragm contributes 75% of the total inspiratory muscle force. Diaphragm: Anatomy 
• Impairment in fetal breathing, which is important for lung maturation:
  • Neuromuscular:
    • Spinal muscular atrophy Atrophy Decrease in the size of a cell, tissue, organ, or multiple organs, associated with a variety of pathological conditions such as abnormal cellular changes, ischemia, malnutrition, or hormonal changes. Cellular Adaptation
    • Congenital Congenital Chorioretinitis myotonic dystrophy
  • Restrictive:
    • Congenital Congenital Chorioretinitis thoracic dystrophy
    • Short rib polydactyly Polydactyly A congenital anomaly of the hand or foot, marked by the presence of supernumerary digits. Physical Examination of the Newborn syndrome
  • Brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification stem impairment of normal breathing patterns

Clinical Presentation

Antenatal

• Decreased fetal movement during pregnancy Pregnancy The status during which female mammals carry their developing young (embryos or fetuses) in utero before birth, beginning from fertilization to birth. Pregnancy: Diagnosis, Physiology, and Care
• Oligohydramnios Oligohydramnios Oligohydramnios refers to amniotic fluid volume less than expected for the current gestational age. Oligohydramnios is diagnosed by ultrasound and defined as an amniotic fluid index (AFI) of ‰¤ 5 cm or a single deep pocket (SDP) of < 2 cm in the 2nd or 3rd trimester. Oligohydramnios
• Ultrasound detection of anatomic malformations or masses
• Ultrasound detection of other congenital Congenital Chorioretinitis abnormalities
• Prenatal diagnosis of associated chromosomal abnormalities 

Postnatal

• Often lethal
• Babies who survive the immediate neonatal period may have:
  • Mild to severe respiratory distress
  • Bell-shaped thoracic cavity in bilateral pulmonary hypoplasia Hypoplasia Hypoplastic Left Heart Syndrome (HLHS)
  • Asymmetrical ventilation Ventilation The total volume of gas inspired or expired per unit of time, usually measured in liters per minute. Ventilation: Mechanics of Breathing and decreased ventilation Ventilation The total volume of gas inspired or expired per unit of time, usually measured in liters per minute. Ventilation: Mechanics of Breathing on the affected side, if unilateral
  • Imaging showing:
    • Space-occupying lesion such as CPAM
    • Interthoracic abdominal contents on the affected side
  • Bronchopulmonary dysplasia
  • Alveolar hemorrhage
  • Pneumothorax Pneumothorax A pneumothorax is a life-threatening condition in which air collects in the pleural space, causing partial or full collapse of the lung. A pneumothorax can be traumatic or spontaneous. Patients present with a sudden onset of sharp chest pain, dyspnea, and diminished breath sounds on exam. Pneumothorax
  • Renal mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast or enlarged bladder Bladder A musculomembranous sac along the urinary tract. Urine flows from the kidneys into the bladder via the ureters, and is held there until urination. Pyelonephritis and Perinephric Abscess
  • Classic Potter syndrome Potter syndrome Potter sequence, which is due to severe oligohydramnios and the compressive effect of enlarged kidneys: positional limb deformities, craniofacial abnormalities, pulmonary hypoplasia, growth impairment, and feeding difficulties. Autosomal Recessive Polycystic Kidney Disease (ARPKD) features:
    • Potter facies
    • Pulmonary hypoplasia Hypoplasia Hypoplastic Left Heart Syndrome (HLHS)
    • Limb deformities
• If mild at birth, later development of:
  • Recurrent pulmonary infections Recurrent pulmonary infections Selective IgA Deficiency
  • Exercise intolerance

Complications

• Immediate neonatal period:
  • Acute respiratory failure Respiratory failure Respiratory failure is a syndrome that develops when the respiratory system is unable to maintain oxygenation and/or ventilation. Respiratory failure may be acute or chronic and is classified as hypoxemic, hypercapnic, or a combination of the two. Respiratory Failure
  • Pneumothorax Pneumothorax A pneumothorax is a life-threatening condition in which air collects in the pleural space, causing partial or full collapse of the lung. A pneumothorax can be traumatic or spontaneous. Patients present with a sudden onset of sharp chest pain, dyspnea, and diminished breath sounds on exam. Pneumothorax
  • Tracheomalacia Tracheomalacia A congenital or acquired condition of underdeveloped or degeneration of cartilage in the trachea. This results in a floppy tracheal wall making patency difficult to maintain. It is characterized by wheezing and difficult breathing. Laryngomalacia and Tracheomalacia
  • Pulmonary hypertension Pulmonary Hypertension Pulmonary hypertension (PH) or pulmonary arterial hypertension (PAH) is characterized by elevated pulmonary arterial pressure, which can lead to chronic progressive right heart failure. Pulmonary hypertension is grouped into 5 categories based on etiology, which include primary PAH, and PH due to cardiac disease, lung or hypoxic disease, chronic thromboembolic disease, and multifactorial or unclear etiologies. Pulmonary Hypertension
• Long term:
  • Chronic lung disease
  • Respiratory infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease
  • Limited exercise capacity
  • Poor growth
  • Scoliosis Scoliosis Scoliosis is a structural alteration of the vertebral column characterized by a lateral spinal curvature of greater than 10 degrees in the coronal plane. Scoliosis can be classified as idiopathic (in most cases) or secondary to underlying conditions. Scoliosis

Mnemonic for Potter sequence potter sequence Potter sequence, which is due to severe oligohydramnios and the compressive effect of enlarged kidneys: positional limb deformities, craniofacial abnormalities, pulmonary hypoplasia, growth impairment, and feeding difficulties. Autosomal Recessive Polycystic Kidney Disease (ARPKD)

• P: pulmonary hypoplasia Hypoplasia Hypoplastic Left Heart Syndrome (HLHS) (leads to respiratory insufficiency)
• O: oligohydramnios Oligohydramnios Oligohydramnios refers to amniotic fluid volume less than expected for the current gestational age. Oligohydramnios is diagnosed by ultrasound and defined as an amniotic fluid index (AFI) of ‰¤ 5 cm or a single deep pocket (SDP) of < 2 cm in the 2nd or 3rd trimester. Oligohydramnios (can be the cause or an associated finding)
• T: twisted face (e.g., beaked nose Nose The nose is the human body’s primary organ of smell and functions as part of the upper respiratory system. The nose may be best known for inhaling oxygen and exhaling carbon dioxide, but it also contributes to other important functions, such as tasting. The anatomy of the nose can be divided into the external nose and the nasal cavity. Nose Anatomy (External & Internal), low-set ears Low-set ears DiGeorge Syndrome, prominent epicanthal folds)
• T: twisted skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions
• E: extremity defects (limb malformations)
• R: renal failure Renal failure Conditions in which the kidneys perform below the normal level in the ability to remove wastes, concentrate urine, and maintain electrolyte balance; blood pressure; and calcium metabolism. Renal insufficiency can be classified by the degree of kidney damage (as measured by the level of proteinuria) and reduction in glomerular filtration rate. Crush Syndrome (in utero)

Diagnosis

Antenatal

• Fetal ultrasonography to look for:
  • Oligohydramnios Oligohydramnios Oligohydramnios refers to amniotic fluid volume less than expected for the current gestational age. Oligohydramnios is diagnosed by ultrasound and defined as an amniotic fluid index (AFI) of ‰¤ 5 cm or a single deep pocket (SDP) of < 2 cm in the 2nd or 3rd trimester. Oligohydramnios
  • Decreased fetal movement
  • Growth restriction or anatomic abnormalities
  • Hydrops Hydrops Cholecystitis
  • Intrathoracic masses
  • Ratio of thoracic circumference to abdominal circumference: < 0.6
  • Lung weight:body weight (LW:BW) ratio: 
    • 0.015 if < 28 weeks
    • 0.012 if > 28 weeks
  • Radial alveolar count:
    • Defined as number of alveoli Alveoli Small polyhedral outpouchings along the walls of the alveolar sacs, alveolar ducts and terminal bronchioles through the walls of which gas exchange between alveolar air and pulmonary capillary blood takes place. Acute Respiratory Distress Syndrome (ARDS) that cross a line drawn from a respiratory bronchiole to the nearest connective tissue Connective tissue Connective tissues originate from embryonic mesenchyme and are present throughout the body except inside the brain and spinal cord. The main function of connective tissues is to provide structural support to organs. Connective tissues consist of cells and an extracellular matrix. Connective Tissue: Histology septum
    • < 75% of the standard value
• MRI:
  • Abnormal anatomy
  • Volumetric assessment 
• Chromosomal analysis showing abnormalities associated with pulmonary hypoplasia Hypoplasia Hypoplastic Left Heart Syndrome (HLHS): 
  • Trisomy 21 Trisomy 21 Down syndrome, or trisomy 21, is the most common chromosomal aberration and the most frequent genetic cause of developmental delay. Both boys and girls are affected and have characteristic craniofacial and musculoskeletal features, as well as multiple medical anomalies involving the cardiac, gastrointestinal, ocular, and auditory systems. Down syndrome (Trisomy 21) ( Down syndrome Down syndrome Down syndrome, or trisomy 21, is the most common chromosomal aberration and the most frequent genetic cause of developmental delay. Both boys and girls are affected and have characteristic craniofacial and musculoskeletal features, as well as multiple medical anomalies involving the cardiac, gastrointestinal, ocular, and auditory systems. Down syndrome (Trisomy 21))
  • Trisomy Trisomy The possession of a third chromosome of any one type in an otherwise diploid cell. Types of Mutations 13 ( Patau syndrome Patau syndrome Trisomy 13, or Patau syndrome, is a genetic syndrome caused by the presence of 3 copies of chromosome 13. As the 3rd most common trisomy, Patau syndrome has an incidence of 1 in 10,000 live births. Most cases of Patau syndrome are diagnosed prenatally by maternal screening and ultrasound. More than half of the pregnancies result in spontaneous abortions. Patau Syndrome (Trisomy 13))
  • Trisomy Trisomy The possession of a third chromosome of any one type in an otherwise diploid cell. Types of Mutations 18 (Edwards’ syndrome)

Postnatal

• Initial physical exam:
  • Check level of respiratory distress.
  • Scaphoid abdomen seen with CDH
  • Decreased or absent lung sounds on the affected side
  • Potter syndrome Potter syndrome Potter sequence, which is due to severe oligohydramnios and the compressive effect of enlarged kidneys: positional limb deformities, craniofacial abnormalities, pulmonary hypoplasia, growth impairment, and feeding difficulties. Autosomal Recessive Polycystic Kidney Disease (ARPKD) features (flattened facies, limb malformations)
  • Other physical findings typical for other underlying chromosomal abnormalities:
    • Trisomy 21 Trisomy 21 Down syndrome, or trisomy 21, is the most common chromosomal aberration and the most frequent genetic cause of developmental delay. Both boys and girls are affected and have characteristic craniofacial and musculoskeletal features, as well as multiple medical anomalies involving the cardiac, gastrointestinal, ocular, and auditory systems. Down syndrome (Trisomy 21): hypotonia Hypotonia Duchenne Muscular Dystrophy, murmur, epicanthal folds, simian crease
    • Trisomy Trisomy The possession of a third chromosome of any one type in an otherwise diploid cell. Types of Mutations 13: cleft lip Cleft lip The embryological development of craniofacial structures is an intricate sequential process involving tissue growth and directed cell apoptosis. Disruption of any step in this process may result in the formation of a cleft lip alone or in combination with a cleft palate. As the most common craniofacial malformation of the newborn, the diagnosis of a cleft is clinical and usually apparent at birth. Cleft Lip and Cleft Palate and/or palate Palate The palate is the structure that forms the roof of the mouth and floor of the nasal cavity. This structure is divided into soft and hard palates. Palate: Anatomy, hypotonia Hypotonia Duchenne Muscular Dystrophy, microphthalmia
    • Trisomy Trisomy The possession of a third chromosome of any one type in an otherwise diploid cell. Types of Mutations 18: microcephaly Microcephaly A congenital abnormality in which the cerebrum is underdeveloped, the fontanels close prematurely, and, as a result, the head is small. (desk reference for neuroscience, 2nd ed. ). Fetal Alcohol Spectrum Disorder, clenched fists, convex sole of foot Foot The foot is the terminal portion of the lower limb, whose primary function is to bear weight and facilitate locomotion. The foot comprises 26 bones, including the tarsal bones, metatarsal bones, and phalanges. The bones of the foot form longitudinal and transverse arches and are supported by various muscles, ligaments, and tendons. Foot: Anatomy (rocker bottom)
    • 22q deletion: craniosynostosis Craniosynostosis Craniosynostosis is the premature fusion of 1 or more cranial sutures during the 1st year of life. Craniosynostosis is classified as simple or complex, and can be caused by environmental factors or genetic syndromes. Craniosynostosis, polydactyly Polydactyly A congenital anomaly of the hand or foot, marked by the presence of supernumerary digits. Physical Examination of the Newborn
• Chest X-ray X-ray Penetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release radiant energy. X-ray wavelengths range from 1 pm to 10 nm. Hard x-rays are the higher energy, shorter wavelength x-rays. Soft x-rays or grenz rays are less energetic and longer in wavelength. The short wavelength end of the x-ray spectrum overlaps the gamma rays wavelength range. The distinction between gamma rays and x-rays is based on their radiation source. Pulmonary Function Tests:
  • Bilateral pulmonary hypoplasia Hypoplasia Hypoplastic Left Heart Syndrome (HLHS) is shown by bell-shaped chest and elevation of the diaphragm Diaphragm The diaphragm is a large, dome-shaped muscle that separates the thoracic cavity from the abdominal cavity. The diaphragm consists of muscle fibers and a large central tendon, which is divided into right and left parts. As the primary muscle of inspiration, the diaphragm contributes 75% of the total inspiratory muscle force. Diaphragm: Anatomy.
  • Unilateral pulmonary hypoplasia Hypoplasia Hypoplastic Left Heart Syndrome (HLHS) shows:
    • Opaque hemithorax
    • Rib crowding
    • Ipsilateral mediastinal shift
    • Hyperinflated contralateral lung in unilateral pulmonary hypoplasia Hypoplasia Hypoplastic Left Heart Syndrome (HLHS)
• CT: to confirm hypoplasia Hypoplasia Hypoplastic Left Heart Syndrome (HLHS) and rule out other causes of respiratory distress
• Electrocardiography Electrocardiography Recording of the moment-to-moment electromotive forces of the heart as projected onto various sites on the body’s surface, delineated as a scalar function of time. The recording is monitored by a tracing on slow moving chart paper or by observing it on a cardioscope, which is a cathode ray tube display. Electrocardiogram (ECG)
• Chromosomal analysis in some cases, and counseling for parents
• Pulmonary function tests for older children and adults

Management

Antenatal

• Steroids Steroids A group of polycyclic compounds closely related biochemically to terpenes. They include cholesterol, numerous hormones, precursors of certain vitamins, bile acids, alcohols (sterols), and certain natural drugs and poisons. Steroids have a common nucleus, a fused, reduced 17-carbon atom ring system, cyclopentanoperhydrophenanthrene. Most steroids also have two methyl groups and an aliphatic side-chain attached to the nucleus. Benign Liver Tumors to help with fetal lung maturation in fetuses 24–34 weeks of gestational age Gestational age The age of the conceptus, beginning from the time of fertilization. In clinical obstetrics, the gestational age is often estimated as the time from the last day of the last menstruation which is about 2 weeks before ovulation and fertilization. Pregnancy: Diagnosis, Physiology, and Care
• Tocolytics and antibiotics in the case of premature Premature Childbirth before 37 weeks of pregnancy (259 days from the first day of the mother’s last menstrual period, or 245 days after fertilization). Necrotizing Enterocolitis rupture of membranes
• Amnio-infusion and amniopatch can be attempted.
• Fetal endoscopic tracheal occlusion Fetal Endoscopic Tracheal Occlusion Congenital Diaphragmatic Hernias may improve outcomes for CDH (under investigation):
  • Occlusion blocks the airway Airway ABCDE Assessment, allowing fluid buildup and lung growth.
  • Pulmonary artery Pulmonary artery The short wide vessel arising from the conus arteriosus of the right ventricle and conveying unaerated blood to the lungs. Lungs: Anatomy hypertension Hypertension Hypertension, or high blood pressure, is a common disease that manifests as elevated systemic arterial pressures. Hypertension is most often asymptomatic and is found incidentally as part of a routine physical examination or during triage for an unrelated medical encounter. Hypertension and pulmonary hypoplasia Hypoplasia Hypoplastic Left Heart Syndrome (HLHS) can be minimized.
  • Occlusion (tracheal balloon) is removed before birth and timed to allow for type 2 Type 2 Spinal Muscular Atrophy pneumocyte development and adequate surfactant Surfactant Substances and drugs that lower the surface tension of the mucoid layer lining the pulmonary alveoli. Acute Respiratory Distress Syndrome (ARDS) production.

Postnatal

• Immediate respiratory support as needed; may include:
  • Supplemental oxygen Supplemental Oxygen Respiratory Failure
  • Surfactant Surfactant Substances and drugs that lower the surface tension of the mucoid layer lining the pulmonary alveoli. Acute Respiratory Distress Syndrome (ARDS) administration
  • Endotracheal intubation Intubation Peritonsillar Abscess and mechanical ventilation Ventilation The total volume of gas inspired or expired per unit of time, usually measured in liters per minute. Ventilation: Mechanics of Breathing
  • ECMO
• Inhaled NO for pulmonary hypertension Pulmonary Hypertension Pulmonary hypertension (PH) or pulmonary arterial hypertension (PAH) is characterized by elevated pulmonary arterial pressure, which can lead to chronic progressive right heart failure. Pulmonary hypertension is grouped into 5 categories based on etiology, which include primary PAH, and PH due to cardiac disease, lung or hypoxic disease, chronic thromboembolic disease, and multifactorial or unclear etiologies. Pulmonary Hypertension
• Surgical correction in cases of CDH and other congenital Congenital Chorioretinitis defects
• Address other complications (e.g., cardiac, gastrointestinal)

Prognosis Prognosis A prediction of the probable outcome of a disease based on a individual’s condition and the usual course of the disease as seen in similar situations. Non-Hodgkin Lymphomas

• Primary pulmonary hypoplasia Hypoplasia Hypoplastic Left Heart Syndrome (HLHS) is rare and usually lethal.
• Overall prognosis Prognosis A prediction of the probable outcome of a disease based on a individual’s condition and the usual course of the disease as seen in similar situations. Non-Hodgkin Lymphomas depends on: 
  • Underlying cause
  • Associated conditions
  • Degree of hypoplasia Hypoplasia Hypoplastic Left Heart Syndrome (HLHS)
• Poor prognostic factors:
  • CDH has a 50% mortality Mortality All deaths reported in a given population. Measures of Health Status rate, with worse prognosis Prognosis A prediction of the probable outcome of a disease based on a individual’s condition and the usual course of the disease as seen in similar situations. Non-Hodgkin Lymphomas in:
    • Right-sided lesion
    • Associated pulmonary hypertension Pulmonary Hypertension Pulmonary hypertension (PH) or pulmonary arterial hypertension (PAH) is characterized by elevated pulmonary arterial pressure, which can lead to chronic progressive right heart failure. Pulmonary hypertension is grouped into 5 categories based on etiology, which include primary PAH, and PH due to cardiac disease, lung or hypoxic disease, chronic thromboembolic disease, and multifactorial or unclear etiologies. Pulmonary Hypertension
  • Presence of genetic abnormalities
  • Severe oligohydramnios Oligohydramnios Oligohydramnios refers to amniotic fluid volume less than expected for the current gestational age. Oligohydramnios is diagnosed by ultrasound and defined as an amniotic fluid index (AFI) of ‰¤ 5 cm or a single deep pocket (SDP) of < 2 cm in the 2nd or 3rd trimester. Oligohydramnios for > 2 weeks
  • Rupture of membranes, especially at < 25 weeks of gestation
• Other factors to consider:
  • Infants with unilateral pulmonary hypoplasia Hypoplasia Hypoplastic Left Heart Syndrome (HLHS) can do well if there are no associated lesions or genetic anomalies.
  • Some infants delivered many weeks after premature Premature Childbirth before 37 weeks of pregnancy (259 days from the first day of the mother’s last menstrual period, or 245 days after fertilization). Necrotizing Enterocolitis rupture of membranes can have good outcomes, with improved lung function over time.
  • Pulmonary hypertension Pulmonary Hypertension Pulmonary hypertension (PH) or pulmonary arterial hypertension (PAH) is characterized by elevated pulmonary arterial pressure, which can lead to chronic progressive right heart failure. Pulmonary hypertension is grouped into 5 categories based on etiology, which include primary PAH, and PH due to cardiac disease, lung or hypoxic disease, chronic thromboembolic disease, and multifactorial or unclear etiologies. Pulmonary Hypertension may resolve with good support and management.
• Survivors may have:
  • Chronic lung disease
  • Limited exercise tolerance Tolerance Pharmacokinetics and Pharmacodynamics
  • Increased risk of pulmonary infection

Clinical Relevance

• Congenital diaphragmatic hernia Congenital Diaphragmatic Hernia Pediatric Chest Abnormalities: a congenital Congenital Chorioretinitis defect in the fetal diaphragm Diaphragm The diaphragm is a large, dome-shaped muscle that separates the thoracic cavity from the abdominal cavity. The diaphragm consists of muscle fibers and a large central tendon, which is divided into right and left parts. As the primary muscle of inspiration, the diaphragm contributes 75% of the total inspiratory muscle force. Diaphragm: Anatomy that allows herniation Herniation Omphalocele of abdominal contents into the thorax, leading to pulmonary hypoplasia Hypoplasia Hypoplastic Left Heart Syndrome (HLHS) on the affected side: The types of hernia Hernia Protrusion of tissue, structure, or part of an organ through the bone, muscular tissue, or the membrane by which it is normally contained. Hernia may involve tissues such as the abdominal wall or the respiratory diaphragm. Hernias may be internal, external, congenital, or acquired. Abdominal Hernias are posterolateral Bochdalek (left-sided Bochdalek in 85% of cases), anterior Morgagni, paraesophageal, and hiatal. Mild cases can be repaired in the first days of life with a good long-term prognosis Prognosis A prediction of the probable outcome of a disease based on a individual’s condition and the usual course of the disease as seen in similar situations. Non-Hodgkin Lymphomas. More severe cases require high levels of support, with long-term respiratory, neurodevelopmental, and growth issues and can be lethal.
• Congenital Congenital Chorioretinitis pulmonary airway Airway ABCDE Assessment malformation (CPAM): previously known as congenital Congenital Chorioretinitis cystic Cystic Fibrocystic Change adenomatoid malformation (CCAM): Rare hamartomatous cystic Cystic Fibrocystic Change and adenomatous lesions in the lung can occur in either side of the lung (unilobar or multilobar). If large enough, these lesions can lead to pulmonary hypoplasia Hypoplasia Hypoplastic Left Heart Syndrome (HLHS) and hydrops Hydrops Cholecystitis. Affected children can be asymptomatic at birth or can present with infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease. Other risks include spontaneous pneumothorax Pneumothorax A pneumothorax is a life-threatening condition in which air collects in the pleural space, causing partial or full collapse of the lung. A pneumothorax can be traumatic or spontaneous. Patients present with a sudden onset of sharp chest pain, dyspnea, and diminished breath sounds on exam. Pneumothorax and, rarely, malignancy Malignancy Hemothorax. Management may involve resection before 1 year of age or close observation, depending on the size and other risk factors.
• Oligohydramnios Oligohydramnios Oligohydramnios refers to amniotic fluid volume less than expected for the current gestational age. Oligohydramnios is diagnosed by ultrasound and defined as an amniotic fluid index (AFI) of ‰¤ 5 cm or a single deep pocket (SDP) of < 2 cm in the 2nd or 3rd trimester. Oligohydramnios: amniotic fluid Amniotic fluid A clear, yellowish liquid that envelopes the fetus inside the sac of amnion. In the first trimester, it is likely a transudate of maternal or fetal plasma. In the second trimester, amniotic fluid derives primarily from fetal lung and kidney. Cells or substances in this fluid can be removed for prenatal diagnostic tests (amniocentesis). Placenta, Umbilical Cord, and Amniotic Cavity volume reduced for gestational age Gestational age The age of the conceptus, beginning from the time of fertilization. In clinical obstetrics, the gestational age is often estimated as the time from the last day of the last menstruation which is about 2 weeks before ovulation and fertilization. Pregnancy: Diagnosis, Physiology, and Care: Diagnosis is by ultrasonography: amniotic fluid Amniotic fluid A clear, yellowish liquid that envelopes the fetus inside the sac of amnion. In the first trimester, it is likely a transudate of maternal or fetal plasma. In the second trimester, amniotic fluid derives primarily from fetal lung and kidney. Cells or substances in this fluid can be removed for prenatal diagnostic tests (amniocentesis). Placenta, Umbilical Cord, and Amniotic Cavity index of ≤ 5 cm. The different etiologies include maternal (e.g., medications, preeclampsia Preeclampsia A complication of pregnancy, characterized by a complex of symptoms including maternal hypertension and proteinuria with or without pathological edema. Symptoms may range between mild and severe. Pre-eclampsia usually occurs after the 20th week of gestation, but may develop before this time in the presence of trophoblastic disease. Hypertensive Pregnancy Disorders), placental (e.g., abruption), fetal (e.g., chromosomal abnormalities), and/or idiopathic Idiopathic Dermatomyositis. First-trimester oligohydramnios Oligohydramnios Oligohydramnios refers to amniotic fluid volume less than expected for the current gestational age. Oligohydramnios is diagnosed by ultrasound and defined as an amniotic fluid index (AFI) of ‰¤ 5 cm or a single deep pocket (SDP) of < 2 cm in the 2nd or 3rd trimester. Oligohydramnios carries a poor prognosis Prognosis A prediction of the probable outcome of a disease based on a individual’s condition and the usual course of the disease as seen in similar situations. Non-Hodgkin Lymphomas. For subsequent trimesters, a fetal structural survey is performed, determining fetal abnormalities, along with serial ultrasound monitoring. Short-term improvement can be achieved with amnio-infusion.
• Trisomy 21 Trisomy 21 Down syndrome, or trisomy 21, is the most common chromosomal aberration and the most frequent genetic cause of developmental delay. Both boys and girls are affected and have characteristic craniofacial and musculoskeletal features, as well as multiple medical anomalies involving the cardiac, gastrointestinal, ocular, and auditory systems. Down syndrome (Trisomy 21), or Down syndrome Down syndrome Down syndrome, or trisomy 21, is the most common chromosomal aberration and the most frequent genetic cause of developmental delay. Both boys and girls are affected and have characteristic craniofacial and musculoskeletal features, as well as multiple medical anomalies involving the cardiac, gastrointestinal, ocular, and auditory systems. Down syndrome (Trisomy 21): a genetic syndrome caused by the presence of an extra chromosome Chromosome In a prokaryotic cell or in the nucleus of a eukaryotic cell, a structure consisting of or containing DNA which carries the genetic information essential to the cell. Basic Terms of Genetics 21; associated with advanced maternal age: This syndrome may be suspected on fetal ultrasonography and on prenatal screening Screening Preoperative Care (typically low alpha-fetoprotein Alpha-fetoprotein The first alpha-globulins to appear in mammalian sera during fetal development and the dominant serum proteins in early embryonic life. Hepatocellular Carcinoma (HCC) and Liver Metastases, estriol Estriol A hydroxylated metabolite of estradiol or estrogen that has a hydroxyl group at C3, 16-alpha, and 17-beta position. Estriol is a major urinary estrogen. During pregnancy, a large amount of estriol is produced by the placenta. Isomers with inversion of the hydroxyl group or groups are called epiestriol. Noncontraceptive Estrogen and Progestins) and confirmed with genetic testing Genetic Testing Detection of a mutation; genotype; karyotype; or specific alleles associated with genetic traits, heritable diseases, or predisposition to a disease, or that may lead to the disease in descendants. It includes prenatal genetic testing. Myotonic Dystrophies. Classic features include hypotonia Hypotonia Duchenne Muscular Dystrophy, short neck Neck The part of a human or animal body connecting the head to the rest of the body. Peritonsillar Abscess, epicanthal folds, cardiac defects, and simian crease. There is an increased incidence Incidence The number of new cases of a given disease during a given period in a specified population. It also is used for the rate at which new events occur in a defined population. It is differentiated from prevalence, which refers to all cases in the population at a given time. Measures of Disease Frequency of pulmonary hypoplasia Hypoplasia Hypoplastic Left Heart Syndrome (HLHS).
• Trisomy Trisomy The possession of a third chromosome of any one type in an otherwise diploid cell. Types of Mutations 18 (Edwards’ syndrome): the 2nd most common trisomy Trisomy The possession of a third chromosome of any one type in an otherwise diploid cell. Types of Mutations. This genetic syndrome is caused by the presence of 3 copies of chromosome Chromosome In a prokaryotic cell or in the nucleus of a eukaryotic cell, a structure consisting of or containing DNA which carries the genetic information essential to the cell. Basic Terms of Genetics 18, with predominance in girls. Characteristic features include intrauterine growth restriction, cardiac defects, clenched fists with overlapping fingers, and rocker bottom feet. Other findings can include diaphragmatic eventration and lung hypoplasia Hypoplasia Hypoplastic Left Heart Syndrome (HLHS). Diagnosis is made by karyotype Karyotype The full set of chromosomes presented as a systematized array of metaphase chromosomes from a photomicrograph of a single cell nucleus arranged in pairs in descending order of size and according to the position of the centromere. Congenital Malformations of the Female Reproductive System analysis. No treatment is available, and many patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship do not survive beyond 1 year of life.
• Trisomy Trisomy The possession of a third chromosome of any one type in an otherwise diploid cell. Types of Mutations 13 ( Patau syndrome Patau syndrome Trisomy 13, or Patau syndrome, is a genetic syndrome caused by the presence of 3 copies of chromosome 13. As the 3rd most common trisomy, Patau syndrome has an incidence of 1 in 10,000 live births. Most cases of Patau syndrome are diagnosed prenatally by maternal screening and ultrasound. More than half of the pregnancies result in spontaneous abortions. Patau Syndrome (Trisomy 13)): the 3rd most common trisomy Trisomy The possession of a third chromosome of any one type in an otherwise diploid cell. Types of Mutations: This genetic syndrome is caused by the presence of 3 copies of the 13th chromosome Chromosome In a prokaryotic cell or in the nucleus of a eukaryotic cell, a structure consisting of or containing DNA which carries the genetic information essential to the cell. Basic Terms of Genetics. Clinical features include brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification and spinal cord Spinal cord The spinal cord is the major conduction pathway connecting the brain to the body; it is part of the CNS. In cross section, the spinal cord is divided into an H-shaped area of gray matter (consisting of synapsing neuronal cell bodies) and a surrounding area of white matter (consisting of ascending and descending tracts of myelinated axons). Spinal Cord: Anatomy malformations, cardiac defects, eye defects, cleft lip Cleft lip The embryological development of craniofacial structures is an intricate sequential process involving tissue growth and directed cell apoptosis. Disruption of any step in this process may result in the formation of a cleft lip alone or in combination with a cleft palate. As the most common craniofacial malformation of the newborn, the diagnosis of a cleft is clinical and usually apparent at birth. Cleft Lip and Cleft Palate/ palate Palate The palate is the structure that forms the roof of the mouth and floor of the nasal cavity. This structure is divided into soft and hard palates. Palate: Anatomy, and hypotonia Hypotonia Duchenne Muscular Dystrophy. This syndrome is also associated with pulmonary hypoplasia Hypoplasia Hypoplastic Left Heart Syndrome (HLHS). Diagnosis is made by karyotype Karyotype The full set of chromosomes presented as a systematized array of metaphase chromosomes from a photomicrograph of a single cell nucleus arranged in pairs in descending order of size and according to the position of the centromere. Congenital Malformations of the Female Reproductive System analysis. No treatment is available, and most patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship do not survive beyond 1 year of life.