TRACHEOESOPHAGEAL FISTULA (TEF)
Esophageal atresia (EA) with or without tracheoesophageal fistula (TEF) is a life-threatening surgical emergency in newborns, seen in ~1:3000-5000 live births and carries high mortality, unless operated within 24 hours of birth.
Embryogenesis: Esophagus and trachea develop from a common primitive foregut, separated by a tracheoesophageal septum. EA usually results from posterior deviation of this septum, while its incomplete development results in concurrent TEF. EA without TEF may also result from incomplete canalization of the primitive esophagus.
Other congenital anomalies are present in ~50% cases, including VACTERL association, i.e. Vertebral, Anorectal, Cardiac, Tracheoesophageal fistula, Renal/Radial and Timb defects.
Pathogenesis: Due to blocked esophageal passage and fistulous communication, these babies develop regurgitation and aspiration of feeds or gastric secretions soon after birth, with chemical pneumonitis and subsequent secondary bacterial pneumonia.
Anatomical types: Various anatomical variations of these defects are as follows (Fig. 14.6):
• Type I (85%): Most common type, in which a fistula connects lower end of esophagus with trachea while upper end of esophagus is blind.
• Type II (8%): Both, the upper as well as lower end of esophagus are blind with no fistula.
• Type III (4%) is an H-type fistula, with no EA but a connecting tract between trachea and esophagus, usually at the level of carina. Frequently missed at birth, these cases present in infancy with recurrent aspiration.
• Type IV (lt;2%): A fistulous connection between upper esophageal pouch and trachea, with blind lower end of esophagus.
• Type V (lt;1%): Two separate fistulous tracts between blind upper and lower ends of esophagus, with EA.
Clinically, all cases except H-type, present within a few hours of birth with:
• Persistent, copious, fine, white, frothy bubbles of mucus in mouth,
• Recurrent episodes of coughing, cyanosis and choking at the time of feeding with progressive respiratory distress due to aspiration pneumonia,
Fig.
14.6: Anatomical types of TEF.• Progressive abdominal distension in type I, due to air passage from trachea to lower end of esophagus or scaphoid abdomen in type II/IV due to blind lower end.
• Failure or difficulty to pass a nasogastric tube at birth for gastric aspiration or feeding at birth.
Most of these babies are preterms and have history of maternal polyhydramnios due to impaired swallowing of amniotic fluid by fetus.
Children with H-type fistula are usually missed in neonatal period and present later with recurrent aspiration pneumonia.
Diagnosis: Early diagnosis of EA/TEF requires high index of suspicion, though routine check for esophageal patency after birth is not necessary in all newborns. Diagnosis may be confirmed by:
• Plain chest and abdominal skiagram after passing a nasogastric tube with radioopaque line to see—(a) the curled-up tube suggestive of blocked esophageal passage (Fig. 14.7), (b) presence or absence of gas shadow in stomach, depending on whether lower end of esophagus is connected with trachea, and (c) presence or absence of aspiration pneumonia.
• H-type fistula is difficult to detect, although milk scan and bronchoscopy to see tracheal end of fistula or video- esophagogram may be useful.
• Abdominal USG and other relevant investigations are necessary to exclude associated anomalies.
Prenatal diagnosis is possible only in ~40% cases, which must be suspected in presence of maternal polyhydramnios and small or absent stomach bubble on USG. Fetal MRI is more reliable.
Treatment: EA/TEF should be operated as early as possible, at least within 24 hours of birth, before the development of aspiration pneumonia.
Pre-operative stabilization of these cases includes:
• Nursing in prone position to reduce the risk of aspiration,
• Continuous suction of the upper esophageal pouch,
• Maintenance of temperature and parenteral nutrition,
• Prophylactic antibiotics and
• Humidified oxygen or ventilatory support, if necessary.
Surgical options depends on the length of atretic esophageal segment and general condition of the patient, as follows:
• Stable patients with small atretic defects are usually taken for immediate corrective surgery with trans-thoracic ligation of fistula with end-to-end esophageal anastamosis. Oral feeding may be resumed after 8-12 days of primary anastamosis.
• Sick children or those with long defects are operated in two-stages-initial gastrostomy for decompression and later primary repair, which may require esophageal reconstruction surgery, using a gastric or colonic tube.
Fig. 14.7: Tracheoesophageal fistula
(Note: Arrows showing coiled-up nasogastric tube)
Outcome depends on the timing of surgery and presence of associated malformations. With first-day surgery before aspiration, survival rate is ~80%, though late complications, e.g. GERD or esophageal stenosis are common.
14.6.2