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Atresia is a condition in which an orifice or passage in the body is (usually abnormally) closed or absent.[1]

Types

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Anotia

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Main article: Anotia

Anotia is characterized by the complete absence of the ear and is extremely rare. This condition may affect one or both ears, though one missing ear is more common. Anotia is also linked to conductive hearing loss, a condition in which sound waves do not travel well through the ear and sound is not efficiently conducted from the outer ear canal to the eardrum. Anotia has no known cause. An associated syndrome, such as Treacher Collins or Goldenhar syndrome, may affect up to 40% of patients. Anotia is typically diagnosed through a physical examination at birth. Prenatal ultrasounds may help with early detection. Total ear reconstruction is the standard treatment for Anotia.[2]

Biliary atresia

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Main article: Biliary atresia

Biliary atresia (BA) is a rare disease marked by an unknown-origin biliary obstruction that manifests in the neonatal period. The classic clinical triad of Biliary atresia is acholic stools, and dark urine, jaundice, and hepatomegaly. The clinical manifestations are used to make the diagnosis, which is supported by liver ultrasonography, cholangiography, and a liver biopsy.[3] The initial treatment is surgical, with the obliterated extrahepatic bile duct resected and a hepatoportoenterostomy created.[4]

Bronchial atresia

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Main article: Bronchial atresia

Bronchial atresia is a rare congenital disease characterized by segmental or lobar emphysema and, in some cases, mucoid impaction. The exact cause of bronchial atresia is unknown; the lobar bronchi, subsegmental bronchi, and distal bronchioles develop in the fifth, sixth, and sixteenth weeks of fetal development, respectively. Bronchial atresia is frequently discovered incidentally because it is asymptomatic. Recurrent pulmonary infections are among the most frequent clinical manifestations in symptomatic patients. Because such benign disease frequently affects young patients, minimally invasive surgery, such as thoracoscopic surgery, is advised.[5]

Choanal atresia

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Main article: Choanal atresia

Choanal atresia (CA) is a rare but well-known condition marked by the anatomical closure of the posterior choanae in the nasal cavity. CA presents clinically in a variety of ways, ranging from acute airway obstruction to chronic recurrent sinusitis, depending on whether it is unilateral, bilateral, or paired with other coexisting airway abnormalities, as is common in individuals who have CHARGE syndrome and craniofacial anomalies. The initial clinical evaluation consists of inserting a six or eight Fr suction catheter through the nostrils, performing a methylene blue dye test, a cotton wisp test, and a laryngeal mirror test. In patients with proper nasal preparation, a CT of the sinuses with 2-5 mm cuts provides a definitive evaluation.[6]

Esophageal atresia

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Main article: Esophageal atresia

Esophageal atresia (EA) is a rare congenital malformation characterized by a lack of continuity between the lower and upper esophageal pouches, often associated with tracheoesophageal fistula.[7] Esophageal atresia with or without tracheoesophageal fistula (TEF) is the most common birth defect of the esophagus. The diagnosis of EA usually occurs within the first 24 hours of life, but it can be made antenatally or later.[8] Although environmental effects and genetic factors have been documented, the causes of EA remain largely unknown.[9] Treatment is surgical and includes reconstruction of the continuity of the esophagus or replacement by other organs.[10]

Follicular atresia

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Main article: Follicular atresia

Follicular atresia refers to the process in which a follicle fails to develop, thus preventing it from ovulating and releasing an egg.[11] It is a normal, naturally occurring progression that occurs as mammalian ovaries age. Approximately 1% of mammalian follicles in ovaries undergo ovulation and the remaining 99% of follicles go through follicular atresia as they cycle through the growth phases. In summary, follicular atresia is a process that leads to the follicular loss and loss of oocytes, and any disturbance or loss of functionality of this process can lead to many other conditions.[12]

Imperforate anus

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Main article: Imperforate anus

Imperforate anus is a somewhat common anomaly, with a newborn incidence ranging from 1: 1500 to 1:5000. There have been isolated cases of imperforate anus, but this condition is more commonly found as one among numerous anomalies. Imperforate anus is usually not diagnosed until after birth. There is no need for immediate reconstructive anorectal surgery. However, prompt evaluation is critical, and urgent decompressive surgery may be required.[13]

Intestinal atresia

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Main article: Intestinal atresia

With an incidence of 1 in 5,000 newborns, intestinal atresias are one of the most common causes of neonatal intestinal obstruction. The majority of cases are small intestinal atresia, while colonic atresias are uncommon.[14] There have been two main etiologies proposed for intestinal atresia: the first is a lack of re-vacuolization of the solid cord stage of intestinal development, and the second is a late intrauterine mesenteric vascular accident. Prenatal ultrasonography is the most reliable way to diagnose intestinal artesia. Pre-operative management includes primary resuscitation, correction of dehydration, and correction of electrolyte abnormalities. Kimura's diamond-shaped duodeno-duodenostomy is the most common surgical treatment.[15]

Microtia

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Main article: Microtia

Microtia is a congenital deformity where the auricle (external ear) is underdeveloped. A completely undeveloped pinna is referred to as anotia. Because microtia and anotia have the same origin, it can be referred to as microtia-anotia.[16] Microtia can be unilateral (one side only) or bilateral (affecting both sides). Microtia occurs in 1 out of about 8,000–10,000 births. In unilateral microtia, the right ear is most commonly affected. It may occur as a complication of taking Accutane (isotretinoin) during pregnancy.[17]

Potter sequence

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Main article: Potter sequence

Potter's sequence is a fatal sporadic and autosomal recessive disorder with an incidence of 1 in 4000 births. Babies born with this defect are either stillborn or die very soon after birth. It primarily affects male babies and is associated with severe oligohydramnios, polycystic kidney, bilateral renal agenesis, and obstructive uropathy during the middle gestational weeks. The main defect in Potter's sequence is renal failure. Premature birth, breech presentation, atypical facial appearance, and limb malformations are other distinguishing characteristics. In most infants, severe respiratory insufficiency results in death.[18]

Renal agenesis

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Main article: Renal agenesis

Renal agenesis occurs when the ureteric bud doesn't fuse with the metanephric blastema during embryogenesis, leading to the nephron and, in some cases, the ureter being absent. Unilateral renal agenesis occurs in 1 in 1000 live births, in contrast bilateral renal agenesis occurs in 1 in 3000 to 4000 pregnancies. Unilateral renal agenesis has a very good prognosis, whereas bilateral renal agenesis has a high rate of perinatal mortality and morbidity due to the lack of amniotic fluid, resulting in lethal pulmonary hypoplasia. The diagnosis of renal agenesis is usually made during a midgestation anatomy ultrasound examination. A genetic syndrome or other anomalies are linked to approximately 30% of cases of renal agenesis.[19]

Tricuspid atresia

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Main article: Tricuspid atresia

Tricuspid atresia is a form of congenital heart disease whereby there is a complete absence of the tricuspid valve.[20] Therefore, there is an absence of right atrioventricular connection.[20] This leads to a hypoplastic (undersized) or absent right ventricle. This defect is contracted during prenatal development, when the heart does not finish developing. It causes the systemic circulation to be filled with relatively deoxygenated blood. The causes of tricuspid atresia are unknown.[21]

Vaginal atresia

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Main article: Vaginal atresia

Vaginal atresia is a birth defect that causes uterovaginal outflow tract obstruction. It happens when the urogenital sinus fails to form the caudal portion of the vagina. Fibrous tissue replaces the caudal portion of the vagina. Vaginal atresia is thought to affect one in every 5000-10,000 live female births. The anomaly is frequently undetected until adolescence, when primary amenorrhea or abdominal pain caused by an obstructed uterovaginal tract leads to a diagnostic evaluation.[22]

References

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Atresia

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from Grokipedia
Atresia is a congenital condition characterized by the absence or pathological closure of a normal body opening, passage, or tubular structure during fetal development. This malformation prevents the flow of fluids, air, or other substances through the affected area, often leading to life-threatening complications in newborns if untreated. The term derives from words meaning "without ," and it applies to a range of birth defects impacting various organ systems, most commonly the gastrointestinal, cardiovascular, and respiratory tracts. Common types of atresia include those affecting the digestive system, such as , where the esophagus ends in a blind pouch and fails to connect to the stomach, causing feeding difficulties and aspiration risks; , a blockage in the first part of the small intestine that presents with vomiting and abdominal distension; and , involving the destruction or absence of bile ducts outside the liver, leading to and liver damage. Cardiovascular examples encompass , in which the is absent or underdeveloped, impeding blood flow to the lungs, and tricuspid atresia, where the does not form, resulting in inadequate oxygenation of blood. Other notable forms are , a blockage of the nasal passages that can cause respiratory distress in infants, and aural atresia, the underdevelopment or absence of the external , often associated with . These conditions collectively account for a small but significant portion of congenital anomalies, with incidences varying by type—for instance, esophageal atresia occurs in about 1 in 2,500 to 4,000 live births. The etiology of atresia is typically multifactorial, involving disruptions in embryonic development due to a combination of genetic predispositions, environmental influences, and sometimes vascular insults that compromise nutrient supply to developing tissues. While specific causes remain elusive for many cases, certain associations exist, such as chromosomal abnormalities (e.g., trisomy 21 with ) or maternal factors like . Diagnosis often occurs prenatally via or postnatally through imaging and clinical signs like or failure to pass a . Treatment invariably requires surgical correction shortly after birth to reconnect or bypass the obstructed structure, with outcomes depending on the type, associated anomalies, and timely intervention—modern techniques have improved survival rates to over 90% for many isolated cases. Beyond congenital forms, the term atresia also describes physiological processes, such as in the ovaries, where ovarian follicles degenerate and fail to mature, a normal aspect of female that regulates egg production throughout life. However, this usage is distinct from the pathological congenital malformations that dominate on the topic.

Definition and Background

Definition

Atresia is defined as the congenital or acquired absence, closure, or obstruction of a natural , passage, or vessel, preventing normal flow or function. This condition is distinguished into pathological atresia, which represents an abnormal developmental failure in organ formation, and physiological atresia, a normal degenerative process such as the resorption of ovarian follicles during reproductive life. Commonly affected structures encompass tubes, ducts, valves, and canals across various organ systems, including the gastrointestinal and biliary tracts. Primarily congenital in nature, major forms of atresia collectively affect approximately 1 in 5,000 live births.

Etymology

The term "atresia" originates from the Ancient Greek words a- (ἀ-, meaning "without" or "not") and trêsis (τρῆσις, meaning "perforation" or "opening"), literally denoting "without opening" or "imperforate." This etymological root reflects the concept of occlusion or absence of a natural passage, derived through Modern Latin atresia from the Greek adjective atrêtos ("not perforated"). The term first appeared in in the early , with the earliest documented use in 1807 in an English medical by R. Morris and J. Kendrick. Initially, it described pathological processes involving the degeneration and closure of anatomical structures, particularly the absence or disappearance of ovarian follicles through a non-developmental or non-rupturing mechanism. This application aligned with emerging observations in reproductive , where "atresia" captured the failure of follicular maturation. Over the course of the 19th and 20th centuries, the evolved from its primary focus on descriptive in reproductive tissues to a broader, standardized usage in and . It became integral to classifying congenital anomalies affecting tubular or canal-like structures, emphasizing developmental failures in organ formation rather than solely degenerative processes. This shift paralleled advances in understanding embryonic development and congenital malformations.

Pathophysiology and Etiology

Developmental Mechanisms

Atresia in congenital malformations of hollow organs, such as those in the gastrointestinal and respiratory systems, primarily arises during the phase of embryonic development, which occurs between weeks 4 and 8 of when primitive tubular structures form from endodermal precursors. This period involves critical processes like epithelial proliferation, mesenchymal interactions, and lumen formation, where disruptions can lead to incomplete organ development. The principal biological mechanisms underlying atresia include failed canalization, in which the initial solid cord-like stage of organ primordia fails to recanalize into a hollow tube; excessive () resulting in tissue resorption; and vascular disruptions that cause ischemic and subsequent obliteration of the lumen. For instance, in the developing intestine, the gut temporarily occludes as a solid mass around week 6, and incomplete vacuolization or apoptotic remodeling can produce atresia, while in utero vascular accidents may lead to segmental and gap formation during weeks 7-8. These mechanisms are not mutually exclusive and often interplay, with vascular events potentially triggering secondary . Atresias are morphologically classified into four main types as a general framework applicable to systems like the : Type I, characterized by a mucosal web or intraluminal diaphragm with intact muscular layers and ; Type II, featuring a fibrous cord connecting the blind-ending proximal and distal segments with preserved ; Type III, involving a complete gap between segments often accompanied by discontinuity; and Type IV, consisting of multiple atresias resembling "apple peel" or scattered gaps. This , originally proposed by Louw and Barnard and later refined, reflects varying degrees of mesenchymal involvement and helps correlate embryological insults with anatomical outcomes. Key genetic and molecular regulators, including and signaling pathways like Sonic Hedgehog (Shh), are essential for proper anteroposterior patterning and epithelial-mesenchymal signaling during tube formation; failures in these pathways disrupt ventral specification and lumen patency. Shh, expressed by endodermal cells, induces mesenchymal proliferation and inhibits excessive to maintain gut tube integrity, while (e.g., HoxA, HoxB) guide regional identity—misregulation can lead to septation defects or failure of recanalization. In , for example, ectopic positioning may impair Shh signaling, resulting in defective tracheoesophageal septation. Atresia is distinguished from , which involves partial luminal narrowing without complete obstruction, and from , the complete failure of organ primordium formation leading to total absence of the structure. These distinctions highlight atresia's specific in disrupted lumen maintenance rather than incomplete development or outright non-formation.

Causes and Risk Factors

Atresias, particularly those affecting the gastrointestinal and respiratory tracts, are frequently associated with genetic syndromes. commonly occurs as part of the , a nonrandom cluster of congenital anomalies involving vertebral defects, anal atresia, cardiac defects, , renal anomalies, and limb abnormalities. Mutations in the FOXF1 gene have been identified in some cases of with or related pulmonary malformations, highlighting the role of FOX transcription factors in foregut development. shows a strong link to Trisomy 21 (), occurring in 25-40% of affected infants. Environmental factors contribute to the risk of atresia formation, often interacting with genetic predispositions. Maternal pregestational increases the of esophageal atresia by approximately 70% (adjusted 1.7), likely due to disrupted embryonic signaling pathways during early . Periconceptional maternal smoking elevates the risk of esophageal atresia with or without , with ratios ranging from 1.5 to 2.0 depending on exposure intensity, as evidenced by population-based case-control studies. Maternal alcohol consumption has also been associated with increased risk of esophageal atresia in systematic reviews as of 2024. Exposure to certain teratogens, such as select pesticides or industrial chemicals during the first trimester, has been implicated in increased risks for gastrointestinal atresias, though specific associations vary by agent and require further confirmation. , often linked to , correlates with higher incidence of intestinal atresias, potentially exacerbating vascular disruptions in fetal development. Most cases of atresia follow multifactorial patterns, with the being sporadic rather than mendelian. Familial clustering is rare, observed in about 1-2% of cases, suggesting possible recessive or polygenic contributions in susceptible kindreds. For instance, reports of affected siblings, including dizygotic twins, indicate a genetic susceptibility component, though environmental triggers may be required for expression. Recent research as of 2025 suggests may represent a final common pathway resulting from diverse genetic disruptions in biliary development, often overlapping with multiple congenital syndromes. The remains unknown in 70-90% of atresia cases, depending on the type, with ongoing research exploring epigenetic mechanisms such as alterations that could modulate during embryogenesis. For , up to 90% of isolated cases lack identifiable genetic or environmental causes, while similarly defies singular explanations, prompting investigations into viral or immune-mediated epigenetic influences. These unresolved aspects underscore the need for integrated genomic and environmental studies to uncover precipitating factors.

Clinical Features and Diagnosis

General Presentation

Atresias, congenital malformations characterized by the absence or closure of normal tubular structures or body openings, often manifest in the neonatal period with symptoms that vary by the affected anatomical site. Prenatally, may occur due to impaired fetal swallowing of , particularly in cases involving upper obstructions. Postnatally, common presentations include or feeding difficulties, which arise from the inability to process ingested material, leading to regurgitation or intolerance. Abdominal distension frequently accompanies gastrointestinal atresias as a result of proximal bowel dilation from obstruction, while may appear in atresias affecting respiratory or cardiac structures due to impaired oxygenation or circulation. Systemic effects further highlight the location-dependent nature of these conditions; for instance, gastrointestinal atresias can result in to pass within the first 24-48 hours of life owing to distal obstruction, whereas esophageal or tracheal atresias may provoke respiratory distress from aspiration or airway compromise, and cardiac atresias can lead to through inadequate blood flow. Most atresias are detected at birth through these acute signs, though certain types, such as , may present slightly later, typically in the first few weeks of life with progressive stemming from obstruction. Variations exist between gastrointestinal and cardiac atresias, with the former often emphasizing obstructive symptoms and the latter focusing on circulatory impairments. If left undiagnosed, atresias can rapidly progress to severe complications, including from persistent and fluid losses, secondary to or bacterial translocation across compromised barriers, and multi-organ failure within days due to metabolic derangements or circulatory collapse. Early recognition is critical, as these sequelae can be life-threatening in the vulnerable neonatal period.

Diagnostic Methods

Diagnosis of atresia typically involves a combination of prenatal and postnatal imaging, laboratory evaluations, and a multidisciplinary to confirm the condition and assess associated anomalies. Prenatal detection often relies on fetal , which can identify indirect signs such as and an absent or small bubble, particularly in cases, with the combination of these findings improving diagnostic accuracy. Fetal (MRI) provides enhanced visualization of anatomical details, such as esophageal dilatation or absence of a bubble, aiding in the confirmation of suspected atresias like with . Postnatally, radiographic techniques are fundamental for verification. For instance, in , an attempt to pass a nasogastric tube often fails, coiling within the proximal blind pouch, which is visualized on chest ; subsequent contrast esophagography delineates the blind-ending pouch and any fistulous connections. allows direct inspection of the upper to identify obstructions or malformations in relevant atresias. is employed when cardiac-associated atresias are suspected, evaluating structural heart defects that frequently coexist with gastrointestinal anomalies. Laboratory tests offer supportive diagnostic clues, though they are not definitive alone. In biliary atresia, elevated total bilirubin levels, typically 6-12 mg/dL, with the direct (conjugated) fraction comprising 50-60% of the total serum bilirubin, indicate cholestasis and prompt further investigation. Recent guidelines, such as those from the (as of 2025), recommend screening for conjugated hyperbilirubinemia with direct bilirubin measurement at the 2- to 4-week well-baby visit to facilitate early detection of . A multidisciplinary approach, incorporating neonatologists for initial stabilization, radiologists for imaging interpretation, and geneticists for evaluating syndromic associations, ensures comprehensive confirmation and guides subsequent care. Clinical presentations, such as feeding difficulties, may initiate these diagnostic pathways in neonates.

Management and Treatment

Therapeutic Approaches

The management of atresia requires a multidisciplinary approach involving neonatologists, pediatric surgeons, gastroenterologists, and other specialists to coordinate care and optimize outcomes across various forms of the condition. This team-based strategy ensures comprehensive evaluation and tailored interventions, particularly in neonates presenting with associated anomalies. Initial stabilization is critical upon diagnosis, focusing on preventing complications such as , aspiration, and . Intravenous fluids are administered to maintain hydration and balance, while nasogastric tube decompression helps relieve gastrointestinal obstruction and reduces the risk of aspiration. Broad-spectrum antibiotics are routinely given to mitigate risks, especially in cases involving potential or translocation of . Nothing by mouth status is enforced, with total initiated if prolonged stabilization is needed. Surgical correction remains the cornerstone for most congenital atresias, typically involving primary to restore continuity or reconstruction to bypass the defect. For complex cases with significant gaps, such as long-gap , staged procedures are employed, including initial pouch approximation followed by delayed to allow tissue growth and reduce tension. These approaches are adapted based on the specific type, with gastrointestinal atresias often necessitating urgent surgical intervention to address obstruction. Non-surgical management plays a key role in physiological forms of atresia, such as in ovarian function, where supportive care includes hormonal monitoring to assess reproductive health and intervene if premature ovarian insufficiency develops. In lethal or untreatable variants, is provided to alleviate suffering and support families, often integrating comfort measures alongside life-prolonging efforts when feasible. Stem cell research shows promise for tissue regeneration, with mesenchymal stem cells demonstrating potential in enhancing outcomes for biliary atresia when combined with surgical procedures like the Kasai operation.

Prognosis and Complications

The prognosis for individuals with congenital atresia varies significantly depending on the affected organ system, the presence of associated anomalies, and the timeliness of intervention. For isolated gastrointestinal atresias, such as esophageal or intestinal types, postoperative survival rates exceed 90%, with five-year survival reaching 95% in some cohorts. For biliary atresia, native liver survival after Kasai portoenterostomy is approximately 50-60%, though overall survival exceeds 90% with liver transplantation; for isolated cardiac atresias, long-term survival rates following repair or palliation are generally over 80%. Overall outcomes have improved with advances in neonatal care, though in-hospital mortality can surpass 10% in low-birth-weight infants. Common complications following management of atresia include strictures at repair sites, gastroesophageal reflux, and feeding difficulties, which affect a substantial portion of survivors. Growth delays are frequent, often linked to nutritional challenges and surgical stress, while neurodevelopmental issues arise in up to 6% of cases with gastrointestinal atresias, exacerbated by prematurity or hypoxia. These factors can lead to long-term morbidities such as or recurrent respiratory infections. Quality of life considerations encompass sensory and reproductive impacts specific to certain atresias. For auditory forms like or , bone-conduction hearing aids significantly enhance hearing and speech development, improving outcomes in over 80% of users. In reproductive atresias, such as accelerated contributing to premature ovarian insufficiency, fertility preservation strategies are essential, as oocyte depletion can reduce reproductive potential by mid-adulthood. Long-term follow-up is crucial, particularly for atresias associated with syndromes like VACTERL, where up to 50% of cases involve additional anomalies requiring ongoing monitoring for renal, cardiac, or vertebral issues. Early and multidisciplinary care are key determinants of these outcomes.

Types of Atresia

Anotia

Anotia represents the most severe form of congenital external malformation, characterized by the complete absence of the pinna (external ) and the external auditory . This condition often accompanies anomalies of the middle and structures, leading to significant auditory and structural deficits. Unlike milder forms such as , anotia involves a total failure of auricular development, resulting in a small nodule or bump at the site where the should form, and it is frequently associated with broader craniofacial asymmetries. The incidence of anotia is estimated at approximately 1 in 20,000 to 30,000 live births, though rates vary by population and are often reported in conjunction with , affecting about 1 in 3,800 to 10,000 births combined. It is more commonly unilateral, occurring in roughly 70-90% of cases, with the right ear affected more frequently, and bilateral anotia is exceedingly rare. Profound is a hallmark feature due to the atresia of the external canal and potential malformations, which can severely impact speech development and if untreated; facial asymmetry and other craniofacial anomalies are also prevalent. Anotia is linked to genetic and environmental factors during early embryonic development, sharing mechanisms with other congenital atresias involving disrupted formation. Anotia is associated with syndromes such as (oculo-auriculo-vertebral spectrum) in up to 40% of cases, where it may occur alongside vertebral, ocular, and cardiac defects, though many instances are isolated. Diagnosis typically involves prenatal ultrasound or postnatal clinical examination, confirmed by imaging like CT or MRI to assess middle and involvement. Management focuses on hearing rehabilitation and cosmetic reconstruction. Bone-anchored hearing aids (BAHA) are the primary intervention for , implanted surgically after age 5 when skull thickness is adequate, providing bone-conduction amplification that bypasses the atretic canal. Auricular reconstruction, often using autologous rib cartilage grafts, is generally deferred until age 6 or older to allow for sufficient growth and psychological readiness, with staged procedures to create a functional and aesthetic ear framework.

Biliary Atresia

Biliary atresia is a progressive fibroinflammatory disease characterized by the destruction and obliteration of the extrahepatic bile ducts, leading to and eventual liver damage if untreated. It typically presents in neonates with prolonged appearing between 2 and 8 weeks of age, accompanied by acholic (clay-colored) stools, dark urine, and due to bile accumulation. This condition obstructs flow from the liver to the intestine, resulting in conjugated hyperbilirubinemia and potential progression to . The incidence of biliary atresia is approximately 1 in 10,000 to 15,000 live births worldwide, with higher rates observed in Asian populations, such as 1 in 5,000 to 8,000 births in and . It exhibits a slight female predominance, affecting girls more frequently than boys. As a variant of gastrointestinal atresia with a primary hepatic focus, it stands out due to its cholangiopathic nature rather than direct . Diagnosis relies on a combination of clinical evaluation, laboratory tests, and imaging, with confirmation often requiring invasive procedures. Hepatobiliary using technetium-99m-labeled derivatives is a key noninvasive test; failure of the isotope to appear in the intestines indicates biliary obstruction, though it has a 10% false-positive rate for atresia. Intraoperative cholangiography during provides definitive diagnosis by demonstrating the absence of a biliary tree. Additional supportive findings include elevated serum gamma-glutamyl transferase (GGTP) levels and showing bile ductular proliferation and portal . Early diagnosis is critical, ideally before 8 weeks of age, to optimize treatment outcomes. The primary treatment is the Kasai portoenterostomy procedure, a surgical intervention that connects the hepatic hilum directly to a Roux-en-Y loop of to restore bile drainage. Performed before 60 days of age, it achieves successful bile flow in about 60% of cases, with higher success rates (up to 80%) when done before 45 days. Postoperative management includes to promote bile flow, fat-soluble vitamin supplementation, and nutritional support to mitigate and . If the Kasai procedure fails or advances, orthotopic becomes necessary, serving as the definitive therapy with excellent long-term survival rates exceeding 85% at 5 years post-transplant.

Bronchial Atresia

Bronchial atresia is a rare congenital malformation defined as the focal obliteration of a proximal segmental or lobar , resulting in a blind-ending airway disconnected from the proximal tracheobronchial tree. This anomaly typically arises during early lung bud development between weeks 5 and 17 of , with proposed etiologies including vascular insult or failure of the bronchial bud to connect properly to the . The affected segment receives collateral ventilation primarily through intra-alveolar , bronchoalveolar canals of Lambert, and interbronchiolar channels of Martin, which permit unidirectional airflow but impair normal . The condition has an estimated prevalence of 1.2 cases per 100,000 individuals, showing a male predominance, and is often discovered incidentally during imaging for unrelated issues or in approximately 0.5-1% of resections performed for other pathologies. It most frequently affects the apicoposterior segment of the left upper lobe, though involvement of the right upper lobe or other segments occurs in about 30-40% of cases. Specific radiographic features include a central tubular or ovoid opacity representing the —a mucus-filled dilatation of the atretic , often exhibiting the classic "finger-in-glove" sign—and distal with oligemia due to in the affected segment. While typically in two-thirds of patients, symptomatic cases may present with , wheezing, or recurrent , particularly if secondary develops within the ; neonates or infants with more extensive involvement might exhibit mild respiratory distress. Management of bronchial atresia is conservative for individuals, with regular clinical follow-up and to monitor for complications such as infection or expansion. Surgical resection, usually via (VATS) lobectomy or segmentectomy, is indicated for recurrent infections, significant symptoms, or when raises concern for to exclude . Prognosis is excellent post-resection, with low recurrence rates and minimal long-term morbidity in appropriately selected patients.

Choanal Atresia

Choanal atresia is a congenital anomaly characterized by the complete occlusion of one or both posterior nasal passages (choanae) by a bony or membranous partition, resulting from the failure of the embryonic nasal cavities to canalize properly. This obstruction can be unilateral, affecting approximately 60% of cases, or bilateral in the remaining 40%. The condition has an estimated incidence of 1 in 5,000 to 8,000 live births, making it the most common congenital malformation of the nasal cavity, and it occurs twice as frequently in females as in males. It is often associated with genetic syndromes, with up to 50% of cases linked to conditions such as CHARGE syndrome, which involves mutations in the CHD7 gene. In newborns, who are obligate nasal breathers, bilateral manifests as immediate and severe respiratory distress, often presenting with cyclical that improves during crying as the switches to oral breathing. Unilateral cases typically present later in infancy or childhood with chronic unilateral nasal discharge, congestion, or feeding difficulties, though they rarely cause acute emergencies. is confirmed through clinical evaluation, including failure of passage of a through the nares, and imaging such as computed tomography to assess the nature of the obstruction. Treatment for choanal atresia is primarily surgical, with the transnasal endoscopic approach serving as the standard method for resecting the obstructing tissue while preserving surrounding structures like the and turbinates. For bilateral cases, immediate airway stabilization—such as oral airway placement or —is required before definitive repair, which is ideally performed in the neonatal period. Postoperative stenting is commonly employed for 4 to 6 weeks to maintain patency, though its use remains somewhat controversial due to risks of . Recurrence rates, leading to restenosis, range from 20% to 30%, with higher risks in bilateral cases and those repaired before 1 year of age; revision may be necessary in these instances.

Esophageal Atresia

Esophageal atresia (EA) is a congenital anomaly characterized by a discontinuity in the due to failure of recanalization during embryonic development, resulting in a blind-ending proximal pouch and an absent or incomplete distal segment. This defect often occurs in conjunction with a (TEF), an abnormal connection between the and trachea, which complicates and increases aspiration risk. The Gross classification delineates four primary types based on fistula presence: Type A (isolated EA without TEF, ~8%), Type B (EA with proximal TEF, ~1-2%), Type C (EA with distal TEF, the most common at ~85%), and Type D (EA with both proximal and distal TEF, ~1-3%). Type C predominates due to its embryologic origins in incomplete septation. The condition affects approximately 1 in 3,000 to 4,500 live births worldwide, with a higher incidence in certain populations such as those with maternal or exposure to environmental teratogens. About 50% of cases are associated with VACTERL syndrome, a constellation of vertebral, anal, cardiac, tracheoesophageal, renal, and limb anomalies, underscoring the need for multisystem evaluation. represents a form of upper gastrointestinal atresia with significant respiratory crossover, as fistulas can lead to . Diagnosis is typically suspected at birth due to excessive salivation, with feeds, and inability to pass a nasogastric (NG) tube beyond 10-12 cm, confirmed by showing the coiled tube in the proximal pouch. A contrast esophagogram using water-soluble further delineates the pouch and any , while and renal screen for associated anomalies. Treatment involves prompt surgical intervention, with primary preferred for short-gap defects (<3 cm) via thoracotomy or thoracoscopy to reconnect the esophageal ends and ligate any fistula. For long-gap EA (>3 cm), staged repairs such as the Foker technique (gradual traction) or esophageal substitution with /gastric tube are employed. Survival exceeds 95% in isolated cases with modern care, though outcomes decline to 50-80% in those with major comorbidities per the Spitz . Long-term management addresses gastroesophageal reflux and strictures.

Follicular Atresia

Follicular atresia is the degenerative process involving the loss of ovarian follicles across developmental stages, from primordial to antral, which eliminates approximately 99% of the follicles formed during a female's reproductive lifespan. This physiological mechanism ensures the selection of competent follicles for while maintaining ovarian by removing non-viable or excess structures. It primarily affects granulosa cells within the follicle, leading to their and subsequent follicular resorption. The process occurs continuously throughout reproductive life, beginning and persisting until , with the rate of follicular loss accelerating exponentially in the years preceding due to heightened recruitment and depletion of the . (AMH) levels, produced by granulosa cells of growing follicles, play a key role in modulating this rate by inhibiting excessive primordial follicle recruitment, thereby influencing the pace of atresia; declining AMH correlates with faster reserve exhaustion. Post-, atresia ceases as the follicle pool is depleted, marking the end of ovarian function. At the cellular level, is driven by of granulosa cells, prominently mediated by the Fas/ (FasL) pathway, where FasL binding to Fas receptors on granulosa cells triggers activation and . This pathway is upregulated in atretic follicles, contrasting with survival signals in dominant follicles. Normally, produces no clinical symptoms, as it is a regulated physiological event; however, pathological acceleration, as seen in conditions like (PCOS) due to , can disrupt and manifest as reproductive irregularities. The implications of center on its role in determining , which reflects the quantity and quality of remaining follicles and predicts reproductive potential. As a normal process, it requires no intervention, but accelerated atresia leading to premature ovarian insufficiency may necessitate supportive therapies to address associated symptoms.

Imperforate Anus

Imperforate anus, also known as anal atresia, is a congenital anorectal malformation (ARM) characterized by the absence of a normal anal opening at birth, resulting from abnormal development of the during embryogenesis. This condition encompasses a spectrum of defects ranging from simple cutaneous or membranous coverings of the to more complex malformations involving fistulas between the and adjacent structures. It is part of the broader category of anorectal malformations, where the fails to connect properly to the , leading to potential obstruction of fecal passage. Classification of imperforate anus is primarily based on the position of the distal rectal pouch relative to the muscle and the presence of fistulas, using systems such as the or Krickenbeck classifications. Low-type malformations, or perineal fistulas, occur when the rectum ends below the levator sling and are often associated with a superficial to the , allowing easier surgical access and better functional outcomes. High-type malformations, or supralevator types, involve the rectum ending above the levator muscle, commonly with a rectourethral in males (e.g., to the bulbar or ) or a rectovestibular in females; in females, a more complex cloacal variant may occur where the , , and converge into a single perineal opening. without is rarer, typically presenting as a blind-ending . These distinctions guide preoperative imaging and surgical planning to assess muscle integrity. The incidence of is approximately 1 in 5,000 live births in the United States, with a slight male predominance (about 60% of cases). It is associated with —a constellation of vertebral, anal, cardiac, tracheoesophageal, renal, and limb anomalies—in up to 50% of cases, necessitating comprehensive screening for these comorbidities at . As part of the lower gastrointestinal atresia spectrum, it primarily affects the distal and , distinguishing it from more proximal intestinal obstructions. Treatment typically begins with a diverting in the neonatal period to manage bowel decompression and allow for further evaluation, particularly for high or complex lesions, followed by definitive repair. The posterior sagittal anorectoplasty (PSARP), introduced by and De Vries in 1982, is the gold-standard surgical approach, involving separation of the rectum from any , precise placement within the sphincter complex under direct vision, and anal canal reconstruction to optimize continence. This procedure is usually performed between 2 and 6 months of age, with closure thereafter. Postoperative care includes bowel management programs to address constipation or soiling. Prognosis varies by malformation type and associated anomalies, with low lesions achieving voluntary bowel movements in over 90% of cases, while high lesions or those with poor sacral ratios carry higher risks. affects 10-33% of patients long-term, often due to sphincter dysfunction, sacral anomalies, or tethered cord, though multidisciplinary interventions like and can improve outcomes in 70-80% of affected individuals. Regular follow-up is essential to monitor for complications such as urinary tract issues or recurrent fistulas.

Intestinal Atresia

Intestinal atresia refers to a congenital malformation characterized by a complete or partial obstruction of the intestinal lumen, most commonly affecting the small bowel (, , or ) or, less frequently, the colon. This blockage arises from failure of normal intestinal recanalization during embryonic development or, in the case of jejunoileal atresia, from an vascular insult leading to mesenteric ischemia. The condition is classified into four types based on the Grosfeld system: type I involves a mucosal web or diaphragm with intact bowel wall and ; type II features two blind-ending bowel segments connected by a fibrous cord; type IIIa includes a gap in the with discontinuous bowel; type IIIb is a variant known as apple-peel atresia with a short, coiled distal segment; and type IV consists of multiple atresias resembling a "string of sausages." The incidence of small bowel atresia is approximately 1 in 3,000 to 5,000 live births, with jejunoileal forms being the most common (1 in 3,000 to 5,000) and occurring in 1 in 5,000 to 10,000 births. Colonic atresia is rarer, affecting about 1 in 40,000 live births and accounting for 1.8% to 15% of all intestinal atresias. is associated with (trisomy 21) in 30% to 40% of cases, while other forms show no strong but may involve prematurity in up to 33% of jejunoileal instances. atresias, encompassing jejunal and proximal ileal obstructions, represent a significant subset of these cases and often present as neonatal emergencies. Diagnosis typically begins with prenatal , which may reveal or dilated bowel loops in 29% to 50% of cases, though postnatal confirmation is standard. Plain abdominal X-rays are crucial: shows the classic "double bubble" sign (dilated and proximal ) with absent distal gas, while jejunoileal atresia displays multiple dilated loops proximally. For colonic atresia, a contrast enema is diagnostic, delineating the obstruction level and microcolon distally. Additional imaging, such as upper gastrointestinal contrast studies, helps exclude associated malrotations. Treatment is primarily surgical, following initial stabilization with nasogastric decompression, intravenous fluids, and correction of electrolyte imbalances. For , duodenoduodenostomy (end-to-end ) is the procedure of choice, performed via open or laparoscopic approaches. Jejunoileal atresias require resection of the atretic segment and primary end-to-end , with temporary reserved for complex cases like multiple atresias. Colonic atresia management often involves primary resection and or staged procedures with . Extensive atresias, such as type IV or apple-peel variants, can lead to short gut syndrome, necessitating and potential intestinal rehabilitation. Survival rates exceed 90% with timely intervention in uncomplicated cases.

Microtia

Microtia is a congenital malformation characterized by the underdevelopment or malformation of the external , specifically the pinna (auricle), resulting in a small or abnormally shaped . It is classified into three grades based on severity: grade I involves a smaller-than-normal auricle with all identifiable landmarks present; grade II features a smaller auricle with some subunits underdeveloped or absent, often affecting the superior half more severely; and grade III presents as a rudimentary remnant, sometimes described as a "peanut ," with the lobule rotated anterosuperiorly, which is the most common form. This condition frequently co-occurs with stenosis or atresia of the external auditory , contributing to its classification as a form of aural atresia variant. The incidence of microtia is approximately 1.5 to 2 per 10,000 live births globally, with bilateral cases occurring in 7 to 21% of affected individuals, while unilateral cases predominate and more often affect the right ear. Prevalence is higher in certain populations, such as Native Americans (4 to 12 per 10,000 births), Hispanics (1.9 to 3.4 per 10,000), and Asians (2.2 to 3.2 per 10,000). often presents with due to malformations of the external and structures, and it is commonly associated with , a condition involving underdevelopment of one side of the face, including the , , and . Management of microtia focuses on addressing both aesthetic and functional deficits. If the external auditory canal is present or partially formed, surgical repair of aural atresia may be pursued, guided by the Jahrsdoerfer grading system, which assesses candidacy based on factors like development, with surgery typically delayed until age 6 for optimal outcomes. For ear reconstruction, options include prosthetic devices, which can be adhesive- or implant-based and customized to match the contralateral ear, though they require ongoing maintenance and may incur high costs. Autologous reconstruction using grafts is a preferred long-term approach for many patients, often staged and initiated around age 10 to ensure sufficient donor tissue and patient cooperation during the process.

Potter Sequence

Potter sequence, also known as Potter syndrome, is a lethal congenital condition characterized by a cascade of deformities resulting from severe , primarily caused by bilateral , leading to , limb contractures, and distinctive facial anomalies. The absence of functional kidneys prevents adequate urine production, which is essential for volume, resulting in fetal compression and impaired organ development . This sequence is often linked to genitourinary anomalies such as , where structural defects in the renal system lead to . The incidence of Potter sequence is approximately 1 in 4,000 births, with about 20% of cases attributable to bilateral . It is more prevalent in male infants and represents a rare but devastating outcome of early embryonic disruptions in kidney formation. Key clinical features include the characteristic "Potter facies," marked by a beaked or flattened , low-set , recessed chin, and prominent epicanthal folds, alongside limb deformities such as clubfeet and joint contractures. is the primary cause of incompatibility with extrauterine life, as affected infants typically succumb to within hours to days after birth due to insufficient lung development. Management is limited to palliative care, focusing on comfort measures and family support, as no curative interventions exist for the underlying renal agenesis. Prenatal diagnosis is achieved through ultrasound detection of oligohydramnios, absent fetal bladder, and lack of visible kidneys, often prompting genetic counseling and pregnancy termination discussions.

Pulmonary Atresia

Pulmonary atresia is a congenital heart defect characterized by the complete absence or closure of the pulmonary valve, which prevents blood flow from the right ventricle to the pulmonary artery and lungs. This condition occurs due to abnormal development of the fetal heart during the first eight weeks of pregnancy. There are two primary types: pulmonary atresia with intact ventricular septum (PA/IVS), where the ventricular septum is intact and the right ventricle is often hypoplastic or underdeveloped, and pulmonary atresia with ventricular septal defect (PA/VSD), which features a large VSD allowing some mixing of blood and is considered a severe variant of tetralogy of Fallot. The incidence of is approximately 1 in 6,708 live births , accounting for about 548 cases annually, and it represents roughly 1-3% of all congenital heart defects. In PA/IVS cases, the right ventricle's can vary from mild to severe, while PA/VSD often involves additional major aortopulmonary collateral arteries (MAPCAs) that supply blood to the lungs. Newborns typically present with shortly after birth due to inadequate oxygenation, as the condition relies on a for pulmonary blood flow. Diagnosis is primarily achieved through , which visualizes the absent pulmonary valve, assesses right ventricular , and evaluates blood flow patterns, often confirmed prenatally via fetal echocardiogram or postnatally within hours of birth. Additional tests, such as to detect low oxygen levels, chest X-rays, electrocardiograms, or , may be used to further delineate anatomy, particularly in PA/VSD cases where MAPCAs need mapping. Treatment begins immediately with infusion to maintain patency of the and ensure pulmonary blood flow until surgical intervention. Initial palliative surgery often involves a Blalock-Taussig shunt to direct blood from the to the pulmonary arteries, followed by staged repairs; in PA/IVS, this may include right ventricular decompression, while PA/VSD typically requires unifocalization of MAPCAs, VSD closure, and right ventricle-to-pulmonary artery conduit placement. For cases with severe right ventricular , the is performed in stages to redirect systemic venous return directly to the pulmonary arteries, bypassing the right ventricle. With timely intervention, long-term survival rates reach 80-90%, though patients require lifelong monitoring for arrhythmias, valve issues, or further interventions.

Renal Agenesis

Renal agenesis is a congenital anomaly characterized by the complete absence of one or both kidneys due to arrested development during early embryogenesis, typically between the 4th and 8th weeks of gestation. In unilateral renal agenesis (UA), a single kidney is present and often undergoes compensatory hypertrophy, increasing in size to assume the function of both, allowing most individuals to lead normal lives provided the remaining kidney is healthy. Bilateral renal agenesis (BA), however, results in no functional renal tissue, leading to anuria and dependence on immediate postnatal interventions like dialysis or transplantation for survival, though long-term prognosis remains poor without such support.00681-5/fulltext) The incidence of UA is approximately 1 in 1,000 live births, while BA is rarer, occurring in about 1 in 3,000 to 4,000 births. UA shows a notable association with Müllerian duct anomalies in females, including uterine agenesis, , or didelphys, due to shared embryologic origins of the metanephric and paramesonephric ducts, with up to 30-50% of affected women exhibiting such genital tract malformations. reflects the failure of renal bud induction from the , a form of genitourinary .00681-5/abstract) Key clinical features differ markedly between UA and BA. In BA, the lack of fetal urine production causes severe , which compresses the developing fetus and contributes to the , manifesting as characteristic facial dysmorphism, limb deformities, and . In UA, the solitary kidney's hyperfiltration can lead to in up to 20-30% of cases, along with and an elevated risk of over time. Management strategies are tailored to the type and timing of . For UA, often identified prenatally via or incidentally postnatally, lifelong monitoring includes serial assessments of , renal function via serum creatinine and estimated , and for , with interventions like antihypertensive therapy as needed to mitigate progression to end-stage renal disease. BA, typically diagnosed prenatally through absent renal echoes and , prompts multidisciplinary counseling on the near-100% lethality without extraordinary measures, including options for pregnancy termination where legally available, alongside discussions of neonatal or experimental therapies if pursued.

Tricuspid Atresia

Tricuspid atresia is a congenital heart defect characterized by the complete absence of the tricuspid valve, resulting in no direct communication between the right atrium and right ventricle, and typically leading to a hypoplastic right ventricle. This condition falls under the broader category of cardiac atresias as a form of right heart inflow obstruction. It is classified into types primarily based on the presence and size of a ventricular septal defect (VSD) and the status of pulmonary blood flow: Type I (normally related great arteries, 70-80% of cases) includes subtypes with pulmonary atresia (Ia), pulmonary stenosis (Ib), or no pulmonary stenosis (Ic); Type II (d-transposition of the great arteries, 12-25%) has similar pulmonary flow subtypes (IIa, IIb, IIc); and Type III (other great artery malpositions, 3-6%). Blood flow dynamics depend on these features, with systemic venous return shunting right-to-left across an atrial septal defect (ASD) into the left atrium for mixing with oxygenated blood, while pulmonary flow occurs via the VSD if present. The incidence of tricuspid atresia is approximately 1 in 10,000 live births, making it the third most common cyanotic congenital heart disease. It presents with cyanosis due to obligatory mixing of oxygenated and deoxygenated blood, and survival without intervention is poor, with high mortality in infancy. Diagnosis is primarily achieved through echocardiography, which reveals the absent tricuspid valve, hypoplastic right ventricle, and dependency on an ASD for atrial-level shunting; a restrictive ASD may necessitate urgent intervention to prevent severe cyanosis or acidosis. Additional findings include blood mixing patterns confirming the pathophysiology, often supplemented by electrocardiogram, chest X-ray, or cardiac catheterization if needed. Treatment involves staged surgical palliation to optimize circulation, beginning with balloon atrial septostomy (Rashkind procedure) if the ASD is restrictive to ensure adequate mixing. For pulmonary blood flow management, prostaglandin E1 maintains ductal patency in neonates, followed by procedures like a modified Blalock-Taussig shunt for restricted flow or pulmonary artery banding for excessive flow; the bidirectional Glenn shunt connects the to the pulmonary arteries around 4-6 months, and the (typically at 2-4 years) completes the palliation by routing flow to the pulmonary arteries, often with a fenestrated conduit. With these interventions, approximately 85% of patients survive to adulthood, though lifelong monitoring for complications such as arrhythmias, , or is required.

Vaginal Atresia

Vaginal atresia is a rare congenital malformation characterized by the partial or complete absence of the vaginal canal, often resulting from abnormal development of the Müllerian ducts during embryogenesis, while the uterus and ovaries are typically normal or functional. This condition represents a form of Müllerian duct anomaly and is frequently associated with Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome, particularly in cases involving vaginal agenesis, though isolated vaginal atresia can occur independently with an intact reproductive tract proximal to the obstruction. The imperforate or absent vagina leads to an obstructive anomaly that prevents menstrual outflow, distinguishing it from non-obstructive forms of Müllerian agenesis. The incidence of vaginal atresia is estimated at approximately 1 in 4,000 to 5,000 female live births, making it one of the more common Müllerian anomalies encountered in clinical practice. Patients typically present during adolescence with primary amenorrhea, defined as the absence of menarche by age 15-16 despite normal pubertal development, including breast and pubic hair growth. A hallmark feature is cyclic pelvic or lower abdominal pain, resulting from the accumulation of menstrual blood (hematocolpos or hematometra) in the functional uterus, which can lead to pelvic masses if untreated. External genitalia appear normal, but pelvic examination reveals a blind-ending vaginal pouch or complete absence of the vaginal introitus. Associated anomalies, particularly involving the urinary tract, occur in 30-40% of cases, with renal malformations such as unilateral , ectopic kidneys, or horseshoe kidneys being the most common. These extragenital findings underscore the need for comprehensive evaluation, including renal , to guide management and prevent complications like recurrent infections or . Skeletal anomalies, such as vertebral defects, may also coexist but are less frequent. Treatment focuses on creating a functional vaginal canal to alleviate obstruction, enable , and allow menstrual drainage when a is present. Non-surgical approaches, such as progressive vaginal dilation using dilators, are first-line for milder cases or as adjunct , achieving success in up to 90% of motivated patients. Surgical options include techniques; the Vecchietti procedure, a laparoscopic method that applies traction to form a neovagina over 6-8 days, offers high success rates (around 95%) with minimal scarring. The McIndoe procedure, involving creation of a neovaginal space lined with a split-thickness skin graft and supported by a mold, is effective for complete atresia but requires postoperative dilation to prevent . In cases with functional ovaries but absent (as in some MRKH variants), may be considered for endometrial support if needed, though it is not routinely required given normal ovarian function. Multidisciplinary care involving gynecology, , and is essential for long-term outcomes, including counseling via options.

Aural Atresia

Aural atresia, also known as congenital aural atresia, is a developmental malformation of the external auditory canal characterized by congenital bony or fibrous blockage ranging from to complete absence, resulting in profound . This condition disrupts the normal auditory pathway by preventing sound transmission to the . It is often associated with , a malformation of the auricle, in more than 90% of cases. The incidence of aural atresia is approximately 1 in 10,000 to 20,000 live births. It predominantly affects one ear (unilateral), with a right-sided preference and a 2.5-fold higher occurrence in males compared to females. Diagnosis typically begins with testing in infancy to quantify the degree of , which affects about 90% of cases, though up to 15% may involve sensorineural components. (CT) of the is essential for detailed assessment, evaluating the extent of bony atresia, development, ossicular chain integrity, and positioning to guide treatment planning. further confirms the conductive nature of the hearing impairment once the child is old enough for behavioral testing. Treatment focuses on restoring hearing and typically involves surgical intervention or amplification. Canalplasty, or atresiaplasty, is recommended for unilateral cases with favorable , using an anterior approach to reconstruct the canal and address middle ear anomalies. Candidacy is determined by the Jahrsdoerfer grading system, a 10-point scale assessing factors like stapes presence, development, and position; a score of 7 or higher predicts a 90% chance of achieving near-normal hearing post-surgery. For bilateral cases, unfavorable (Jahrsdoerfer score below 7), or when surgery is declined, bone-anchored hearing aids (BAHA) provide effective amplification, improving hearing by 35-45 dB and supporting early auditory development. Surgical timing is generally around age 5 to minimize risks like injury.

Aortic Atresia

Aortic atresia is a congenital heart defect characterized by the complete absence or closure of the aortic valve orifice, resulting in obstruction of blood flow from the left ventricle to the aorta. This condition typically leads to underdevelopment of the left-sided heart structures, forming a critical component of hypoplastic left heart syndrome (HLHS), where it is observed in approximately 50-60% of cases. As a severe form of left heart outflow tract obstruction, aortic atresia prevents systemic circulation from the left ventricle, forcing reliance on the right ventricle and patent ductus arteriosus (PDA) for blood flow to the body. The incidence of aortic atresia is estimated at about 1 in 4,000 live births, accounting for a subset of left-sided obstructive congenital heart lesions that collectively represent 5-8% of all congenital heart defects. It predominantly affects males, with a ratio of approximately 2:1, and is often associated with other anomalies such as stenosis or atrial septal defects within the HLHS spectrum. Without intervention, closure of the PDA leads to rapid deterioration, contributing to 25% of neonatal cardiac deaths. Diagnosis of aortic atresia begins prenatally through fetal , which reveals absent forward flow across the and reversed flow in the due to the hypoplastic . Postnatally, confirmation relies on demonstrating the atretic valve, small left ventricle, and PDA-dependent systemic perfusion, often accompanied by clinical signs such as and within the first few days of life. Additional imaging like chest may show , while indicates . Treatment for aortic atresia centers on staged palliative surgery to establish single-ventricle physiology, beginning with the in the neonatal period, which reconstructs the using the and creates a systemic-to-pulmonary shunt. Subsequent stages include the at 4-6 months to redirect flow to the pulmonary arteries, followed by the at 2-4 years to complete passive pulmonary blood flow. Emerging hybrid approaches, combining surgical banding of pulmonary arteries with catheter-based stenting of the PDA and atrial , offer alternatives for high-risk infants, potentially delaying or modifying the full Norwood. Overall survival to hospital discharge after stage 1 is approximately 70-85%, with long-term survival post-Fontan reaching 70% at 5-10 years, though aortic atresia variants carry higher mortality risk compared to other HLHS subtypes. infusion is essential preoperatively to maintain PDA patency and prevent systemic hypoperfusion. As a form of cardiovascular atresia, aortic atresia exemplifies the challenges in left heart obstructive lesions but requires distinct management from right-sided variants.

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