Diagnosis of fetal laryngotracheal atresia combined with tracheoesophageal fistula via prenatal ultrasound: a case description

Introduction

Congenital high airway obstruction is a rare but serious condition. In most cases of this disease, laryngeal or proximal tracheal atresia or stenosis occurs, or airway obstruction forms due to laryngeal membranes or laryngeal cysts (1,2). This disease can cause severe respiratory distress in newborns, and if not diagnosed early, serious complications can arise. Prenatal detection is typically achieved through detailed ultrasound examination, and characteristic manifestations such as tracheal abnormalities, bilateral lung enlargement, and enhanced lung echoes can be observed (3,4). Early identification is crucial for guiding clinical decision-making, especially in determining whether surgical intervention is needed after childbirth.

This report presents a case of laryngotracheal atresia diagnosed via prenatal ultrasound and confirmed postpartum. This case highlights the complexity of diagnosing laryngotracheal atresia when combined with tracheoesophageal fistula, a condition that alters typical prenatal ultrasound signs.

Case presentation

A 23-year-old woman (gravida 1 and para 0) was admitted for routine prenatal care with no significant past medical or family history. Early pregnancy ultrasound was unremarkable, and the patient’s screening for Down syndrome indicated a low risk. At 24 weeks of gestation, a detailed ultrasound examination was performed. The findings included bilateral lung enlargement, with the left and right lung’s anteroposterior dimensions measuring 27 and 31 mm, respectively. The echogenicity of the lungs was diffusely increased, and the cardiothoracic ratio was 27%. A hyperechoic nodule, approximately 6.7 mm × 5.2 mm in size, was observed in the upper segment of the trachea. Below this nodule, the tracheal diameter was widened, with the maximum width measuring about 5 mm (Figure 1A). Dynamic observation revealed that at the tracheal bifurcation, the trachea was connected to the lower esophagus (Figure 1B). No diaphragmatic flattening or inversion was observed in either the coronal or sagittal sections. Additionally, no fluid accumulation was present in the thoracic or abdominal cavities, and the amniotic fluid index was 13.5 cm. The final diagnosis was thus prenatal tracheal obstruction combined with a tracheoesophageal fistula.

Figure 1.

Prenatal ultrasound and postnatal bronchoscopy images of the case. (A) Two-dimensional ultrasound showed sagittal fetal upper airway obstruction (arrow) and upper airway dilation. (B) Two-dimensional ultrasound showed that the bifurcation of trachea on the sagittal plane was connected to the lower esophagus (arrow). (C) Chest radiography indicated decreased translucency in both lungs. (D) Bronchoscopy showed complete atresia of the subglottis and tracheal opening. E, esophagus; T, trachea.

After consulting with the medical team, the patient chose to continue the pregnancy. At 35 weeks of gestation, the patient experienced premature rupture of membranes and underwent cesarean delivery of a female neonate weighing 2,310 g. The 1-minute Apgar score of the newborn was 6 (5). During the rescue process, tracheal intubation failed. After 10 minutes of oxygen inhalation support with a mask, the score rose to 7. At this time, a gastric tube was inserted into the child to prevent excessive gas from entering the stomach and to indirectly reduce the increase in abdominal pressure. A chest X-ray showed decreased lung translucency, indicating the presence of neonatal pulmonary edema (Figure 1C). Laryngoscopy and esophagoscopy performed in the neonatal intensive care unit revealed complete obstruction under the glottis and at the tracheal opening, with a blind end at the tracheal end (Figure 1D). The esophagus was unobstructed, and an abnormal circular opening was visible in the middle segment. Bedside echocardiography showed an enlarged right heart, severe pulmonary hypertension, a thinner inner diameter of the aortic isthmus, patent ductus arteriosus, and patent foramen ovale. Further cranial ultrasound revealed ventricular enlargement with possible intraventricular hemorrhage, consistent with a grade III intraventricular hemorrhage. The parents were informed of the child’s prognosis and consented to the discontinuation of life-sustaining measures.

All procedures in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patient (mother) for publication of this article and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Discussion

Fetal laryngotracheal atresia, also known as congenital high airway obstruction, is a rare congenital malformation. In most cases of this disease, it is characterized by laryngeal or proximal tracheal atresia or stenosis or by airway obstruction caused by the laryngeal membranes or laryngeal cysts (1,2). It is extremely rare for the lesion site to be located in the distal part of the trachea. The prognosis of patients with this disease is poor, and its exact prevalence rate remains unclear. However, the pathogenesis of laryngotracheal atresia may be related to abnormal fusion of the sixth pharyngeal arch or failure of recanalization of the larynx at 10 weeks of gestation. The prenatal ultrasound manifestations are as follows: the interruption of anechoic continuity between the fetal larynx and trachea is a direct sign for diagnosing obstruction. The characteristic manifestations include increased volume of both lungs and enhanced echo, dilation of the trachea and main bronchi, flattened or inverted diaphragm, reduced cardiothoracic ratio, and a large amount of peritoneal effusion (3,4). Airway obstruction leads to the obstruction of pulmonary fluid drainage, the intratracheal pressure gradually increases, and the volume of both lungs enlarges. In turn, the enlarged lungs compress the heart and vena cava, causing the heart to be compressed and reduced and the vena cava return to be blocked, thereby resulting in cardiac insufficiency, ascites, placental enlargement, and nonimmune edema. Enlarged lungs can also compress the diaphragm. Depending on the severity, diaphragm abnormalities can manifest as flat or reversed. In the later stage of pregnancy, a compressed esophagus can cause dysphagia in the fetus, and some fetuses may experience polyhydramnios. More than 50% of cases of laryngeal or tracheal obstruction are accompanied by other congenital malformations, including abnormalities of the kidneys, central nervous system, and esophagus (6). The most common genetic disorder associated with congenital high airway obstruction is Fraser syndrome, whose main manifestations include laryngeal and tracheal abnormalities, cryptophthalmos, syndactyly, urinary tract abnormalities, genital ambiguity, and anorectal defects, among others. Other malformations that have been reported to be related to congenital high airway obstruction include cri-du-chat syndrome and short costal polydactyly syndrome.

The case we encountered can be considered complete laryngotracheal atresia combined with tracheoesophageal fistula. Although the prenatal ultrasound showed solid nodules in the lumen of the upper trachea, due to the tracheoesophageal fistula causing the fluid secreted by the lungs to flow through the esophagus, the pressure in both lungs and the trachea was reduced, and the degree of bilateral lung dilation and tracheobronchial dilation was alleviated. Therefore, no typical ultrasound manifestations of high airway obstruction were present in this case; rather, this condition manifested as a relatively mild degree of cardiac compression, with no flattening or inverting of the diaphragm, no fetal ascites, and a normal amniotic fluid volume, leading to difficulties in the accurate prenatal diagnosis of high airway obstruction.

Although the ultrasound images of fetal thoracic changes caused by congenital laryngotracheal atresia are typical, they nonetheless need to be differentiated from other fetal thoracic diseases, including (I) congenital pulmonary airway malformation (CPAM), (II) intralobar sequestration, and (III) congenital bronchial atresia, as described below.

CPAM is a type of malformation of the lung tissue. This condition often presents as unilateral lung lesions. Ultrasound examination may reveal realistic hyperechoic or mixed cystic and solid masses in the thoracic cavity (7). The lesion site is supplied with blood by the pulmonary artery. There may be varying degrees of compression and displacement of surrounding tissues, but the trachea and bronchi do not dilate.

Intralobar sequestration is a pulmonary lesion with vascular malformation, mostly unilateral. The typical feature is a well-defined mass in the thoracic cavity with uniform echo characteristics, and it is supplied with arterial blood by the thoracic aorta. Its growth is not the same as that of the lung tissue, and it does not cause tracheal or bronchial dilation. The prognosis of patients with intralobar sequestration is relatively good.

Congenital bronchial atresia is characterized by local atresia of the bronchi, most commonly occurring in the right upper lobe and rarely in the lower lobe. The primary manifestations on ultrasound are significant enlargement of the affected lung lobe, enhanced echo, blood supply by the pulmonary circulation, and displacement of the heart and mediastinum to the opposite side.

Although laryngotracheal atresia is a rare and fatal congenital disorder, accurate prenatal ultrasound diagnosis is crucial for the prognostic assessment of newborns. The prenatal ultrasound diagnosis of typical cases of laryngotracheal atresia is not difficult. However, when combined with tracheoesophageal fistula, its clinical manifestations and ultrasound signs may be relatively insidious and diagnostically challenging. Therefore, when prenatal ultrasound reveals enhanced lung echoes, regardless of whether other malformations are present, conducting a comprehensive examination of the trachea and bronchi from multiple perspectives is recommended. If high airway obstruction is suspected, a multidisciplinary collaborative diagnosis and a treatment model should be initiated to provide the best treatment plan for the patient.

Conclusions

This report describes a case of laryngotracheal atresia combined with tracheoesophageal fistula diagnosed by prenatal ultrasound. This case indicates that the accurate diagnosis of laryngotracheal atresia by prenatal ultrasound is crucial for the prognosis of newborns. When laryngotracheal atresia is combined with tracheoesophageal fistula, detailed observations from multiple levels and perspectives are required to improve the diagnostic accuracy. Meanwhile, multidisciplinary collaboration should be strengthened to aid in devising optimal treatment plans for patients.

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Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patient (mother) for publication of this article and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.