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•182• Chapter 15 Management of Oesophageal Atresia in a Developing Country like Ghana W. Appeadu-Mensah Definition Oesophageal atresia is a congenital abnormality in which there is a discontinuity in the wall or lumen of the oesophagus with or without an associated trachea-oesophageal fistula. There are, however, two types in which there is no discontinuity in the oesophagus but rather a fistula or a stenosis. It has very good prognosis with early diagnosis and appropriate intervention. Incidence The incidence ranges between 1 in 3,500 and 1 in 4,500 live births world wide.1, ,2 In a retrospective analysis of cases seen at the Korle Bu Teaching Hospital in Ghana, 44 patients were seen over an 8 year period; 22 ( or 50 percent) were male, 15 ( or 39 percent) female while in 5 ( or11 percent) the sex was not recorded. (Unpublished data). Aetiology The aetiology of oesophageal atresia is not known but a number of possible risk factors have been studied.1,4,5,6,7 Possible teratogenic risk factors include, Methimazole, Contraceptive pills, Thalidomide, and Diabetes. 4,5,6 Genetic and chromosomal factors may play a role in a few cases but the majority are sporadic events with no clear-cut causative factor.7 While some association with some of these factors has been noted no single factor can convincingly be said to cause oesophageal atresia. •183• Management of Oesophageal Atresia in a Developing Country like Ghana Pathogenesis The Pathogenesis of oesophageal atresia is not known but is suspected to be due to a failure of cellular proliferation, differentiation and apoptosis.8 Damage usually occurs around the fourth week of gestation. During initial development, the foregut divides into the trachea anteriorly and the oesophagus posteriorly. It is at this stage that an insult leads to oesophageal atresia. A number of proposed theories were summarized by Kluth and Spiegel11 and these include: Theory of foregut occlusion: This theory suggests that there is a period of complete occlusion of the foregut followed later by recanalization. A form of failure of canalization is suggested to explain the pathogenesis of oesophageal atresia. In normal embryogenesis, a phase of complete occlusion of the foregut has never been observed. Theory of spontaneous deviation of the trachea-oesophageal septum: This theory proposes that during normal development, a tracheooesophageal septum forms which divides the foregut into an oesophagus and a trachea. An aberration in the formation of this septumisproposedtocauseoesophagealatresia.Anobviousseptum has never, however, been observed during normal embryogenesis Theory of mechanical pressure: This theory suggests that during the course of embryogenesis ,abnormally high pressures develop which result in impaired formation of the oesophagus and trachea. It is, however, difficult to imagine high pressures at this early stage of embryogenesis. Molecular Pathway It has been shown that an aberration in the genetic pathway involving the sonic hedgehog gene may be involved in the pathogenesis of oesophageal atresia.9,10 •184• Chapter 15 Classification A number of classifications have been proposed but the most useful have been those of Vogt (1929) 14 and Gross (1953) .15 The Gross classification is as follows: Type A Oesophageal Atresia without a fistula; Type B Oesophageal Atresia with a proximal Tracheooesophageal fistula; Type C Oesophageal Atresia with a distal Tracheooesophageal fistula. This is the commonest type encountered. Type D Oesphageal Atresia with double fistula; Type E Isolated Tracheo-oesophageal fistula; Type F Oesophageal stenosis. This classification helps in accurate diagnosis of the type and helps plan the definitive management needed. Associated Anomalies Oesophageal Atresia is associated with other anomalies in about 50 percent to 70 percent of cases.3 Not all, are life-threatening however. Association with cardiac malformations in particular is known to significantly affect prognosis.12 Known associations include VACTERL (Vertebral, Anorectal, Cardiac, Tracheo-esophageal atresia, Renal, Limb) anomalies, CHARGE (Coloboma of the eye, Heart defects, Atresia of the nasal choanae, Retardation of Growth/development, Genital and/or urinary) anomalies, Downs Syndrome and others. This may be due to an early teratogenic event that affects a number of possible organ systems.8 Pathophysiology This depends on the specific type of Oesophageal atresia and any associated congenital anomalies. In the commonest type with a distal fistula, the child is at risk of constant aspiration of saliva and food from the proximal pouch. In addition, there is a constant risk of aspiration of gastric contents. Depending on how much air passes through the •185• Management of Oesophageal Atresia in a Developing Country...