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KEY POINTS
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Key Points

  • Occurs in 1 in 3000 livebirths.

  • Fifty percent of cases have associated anomalies, most commonly cardiac, but also genitourinary, anorectoal, and musculoskeletal.

  • Sonographic diagnosis is inferred by absence of the fetal stomach with polyhydramnios.

  • Differential diagnosis includes congenital diaphragmatic hernia, situs inversus, and musculoskeletal or neurologic abnormalities.

  • Chromosome abnormalities are present in 6% to 10% of cases. Fetal karyotype is indicated. Fetal echocardiogram should be performed.

  • Delivery is not mandated at a tertiary care center.

  • Long-term outcome may be complicated by esophagitis, recurrent strictures, and the development of Barrett’s mucosa.

  • Mutations in the genes N-MYC, CHD7, and SOX2, which cause Feingold syndrome, CHARGE syndrome, and anophthalmia, esophageal atresia, and genital (AEG) syndrome, respectively, are important genetic causes of esophageal atresia.

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CONDITION
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Tracheoesophageal anomalies probably arise as a result of events that occur around the 4th week of gestation. The trachea and esophagus first develop as a ventral diverticulum off of the foregut at 22 to 23 days of gestation (Skandalakis et al., 1994). This diverticulum elongates and there is an influx of endodermal cells that form ridges of tissue, which divide the foregut into esophageal and tracheal lumens beginning at the carina and progressing cephalad. By the 26th day of gestation the esophagus and trachea have become completely separated up to the level of the larynx. Interruption in the in growth of ectodermal ridges is thought to result in tracheoesophageal fistula. However, the cause of esophageal atresia when associated with tracheoesophageal fistula is less well understood. One theory suggests that rapid caudal elongation of the trachea, in the presence of a distal tracheoesophageal fistula, produces fixation of the distal esophagus to trachea (Smith, 1957; Moore and Pessaud, 1993). The dorsal wall of the esophagus is drawn forward and downward to be incorporated with the trachea, and esophageal atresia results. Consequently, the esophageal atresia associated with tracheoesophageal fistula occurs as a direct result of the presence of the fistula. In contrast, isolated, or pure, esophageal atresia is thought to arise as a result of a vascular deficiency.

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More recently, mutations in the hedgehog (Hh) signaling pathway have been implicated in the development of tracheoesophageal fistula (Lees et al., 2005). Studies in transgenic mouse models examining the effects of homozygous sonic hedgehog (Shh) knockout mutations demonstrate esophageal atresia and tracheoesophageal fistula (Litingtung et al., 1998; Ramalho-Santos et al., 2000). The foregut abnormalities become evident as early as embryonic day 9.5 in the mouse when the tracheal diverticulum is developing. The role of hedgehog signaling in esophageal atresia and tracheoesophageal fistula is further supported by Gli 2–/– and Gli 3+/– double knock out mice. These mutations are downstream from sonic hedgehog and also result in esophageal atresia and tracheoesophageal fistula (Lees et al., 2005). Studies performed on biopsies of proximal and distal esophagus in infants ...

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