الفهرس 
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Abstract
our understanding of the embryology of OA/TOF has lagged considerably behiend the dramatic improvement in the survial of affected neosnates this lag reflects continuing lack of clarity of the mechanisms of normal tracheoesophagealembryogenesis in this review we discuss the current understanding of both normal tracheoesophageal development and the distrubances in the molecular , cellular, and morphogenetic mechanisms that underlie the embryogenesisof.Esophageal atresia (OA) represents a congenital developmental anomaly
characterized by anatomical discontinuity of the esophagus such that the lumen is
not patent. (Spitz L ٢٠٠٧).In approximately ٨٥-٨٨٪ of cases OA will be associated
with an abnormal communication between the trachea and esophagus, in ٦-٧٪ there
will be no fistula and in the remainder a fistula but no true OA) (Spitz L ٢٠٠٧;
Goyal A; et al ٢٠٠٦).In those patients with OA and an associated
tracheoesophageal fistula (TOF), the most common arrangement would be a blindending
upper esophageal pouch with a distal fistula: isolated proximal or the
presence of both proximal and distal fistulas occurs much less commonly) (Spitz L
٢٠٠٧; Goyal A; et al ٢٠٠٦).An understanding of these anatomical variants
remains important to facilitate optimal medical and surgical management (Bax KN;
et al ٢٠٠٨The frequency of OA appears fairly consistent in most populations, occurring
between ١ in ٢,٥٠٠ to ٤,٥٠٠ live births (Spitz L ٢٠٠٧).The great majority of cases
occur as a sporadic phenomenon, although the incidence is higher in twins.
Ioannides (AS; Copp AJ ٢٠٠٩).
Perhaps of greater clinical importance remains the high frequency of associated
anomalies, at over ٥٠٪,which may greatly impact on both treatment and outcome.
Ioannides(AS; Copp AJ ٢٠٠٩).
In addition to their frequency, anomalies remain unequally distributed between
patients:
thus those with ‘pure’ or ‘isolated’ OA without fistula have anomalies in up to ٦٥٪
of cases, with a much lower frequency in those with a fistula but no atresia, perhaps
contributing to diagnostic delay(Spitz L ٢٠٠٧). Cardiac defects consistently
account for the greatest number of anomalies and may be a feature of theVACTERL (Vertebral, Atresia – duodenal and anorectal, Cardiac,Tracheoesophageal,
Renal, Limb) and charGE (Coloboma, Heart,Atresiachoanal,
Retarded growthGenitalhyposplasia, Ear deformities) syndromes in addition to OA
associated with Trisomy ١٨ and ٢( Spitz L ٢٠٠٧).In a seminal paper, David Waterston in ١٩٦٢ stratified “risk” criteria based on
birth weight, pneumonia, and associated anomalies( Waterston DJ et al
١٩٦٢.Lewis Spitz and colleagues١٩٩٠). later proposed a new and simpler system
based on associated congenital heart defects and low birthweight status for the
modern era. Survival in babies >١٥٠٠ g and without a major cardiac lesion now
approaches ٩٧٪ (group I), but falls dramatically to only ٢٢٪ (group III) if low birth
weight (<١٥٠٠ g) and a severe heart anomaly coexist(Lewis Spitz et al ١٩٩٠).
Other studies from large centres confirm these findings(Driver CP; et al ٢٠٠١).
Cardiac and chromosomal defects account for most (if not all) early deaths.
Ongoing respiratory complications account for late mortality(Choudhury SR; et
al ١٩٩٩).Whilst atresia remains the most common congenital anomaly of the esophagus,
much has changed in the management of this condition since the first reported
primary repair in ١٩٤١ by Haight.(Haight C ١٩٤٤).Following this description,
successful repairs were performed in ١٩٤٨ at both Great Ormond Street Hospital
for Children in London and at the Royal Children’s Hospital in Melbourne(Myers
NA.١٩٩٢; Spitz L.١٩٩٦).Whereas these early procedures were associated with
mortality rates of ٣٠-٥٠٪, improvements in surgical, anaesthetic and neonatal care
over the last ٥٠ years have resulted in the present situation where survival
following surgery may generally be expected, even for infants with long-gap
defects, prematurity and some associated anomalie(Myers NA.١٩٩٢; Spitz
L.١٩٩٦; Houben CH,Curry JI. ٢٠٠٨).With these improvements, the focus of thecritical lens has moved from mortality to morbidity and quality of life issues (Little
DC; et al ٢٠٠٣