ausEE Inc.

Oesophageal atresia-tracheoesophageal fistula (OA-TOF) is a rare congenital anomaly of the digestive tract with an incidence of 1 in 2500 live births. In Oesophageal atresia (OA) a section of the oesophagus (gullet or food pipe) has not formed properly and therefore the oesophagus is not one continuous tube but has two unconnected parts; an upper pouch and a lower segment. This means the saliva and food cannot pass from the mouth into the stomach as it becomes stuck in the upper blind-ending pouch. Most babies will present at birth with an inability to swallow their secretions. Most babies with OA will also be born with an abnormal connection or 'fistula' between the food pipe (oesophagus) and the windpipe (trachea) which causes air to pass from the windpipe to the stomach and stomach juices to reflux rom the stomach to the lungs both which cause breathing difficulties and dusky episodes soon after birth. Despite improvement in surgical techniques resulting in almost a 100% survival rate, there is a significant long-term gastrointestinal morbidity associated with this condition. All patients have a degree of oesophageal dysmotility that predisposes them to gastroesophageal reflux disease, and often require anti reflux surgery (fundoplication). There is also a high incidence of swallowing difficulties (dysphagia) secondary to oesophageal dysmotility, food getting stuck (impaction), strictures, feeding difficulties, and failure to thrive. Eosinophilic esophagitis (EoE) is an allergic inflammatory condition of the oesophagus that requires more than 15 eosinophils per high power field (HPF) on oesophageal biopsy for it's diagnosis. The symptoms of EoE in children can be similar to those experienced by OA-TOF children and can include swallowing difficulties, food getting stuck, feeding difficulties and vomiting. The association and coexistence of EA and EoE has not been widely reported in the English literature. Recent studies report a higher prevalence of Eosinophilic Esophagitis in OA-TOF patients compared to the general population. The largest reported number was in the study conducted in our own group of OA-TOF patients in Sydney Children's Hospital (SCH) multidisciplinary clinic for OA-TOF patients which reported a 17% incidence. This is significantly greater than the reported incidence of EoE in the general pediatric population, of 1 in 10 000 children.

The etiology of the higher incidence of EoE in the OA-TOF cohort is multifactorial. It has been postulated that underlying genetic abnormalities may not only lead to congital malformations of both the lung and esophagus but also might predispose to EoE. Reflux may also play a role in the pathophysiology of EoE as acid peptic mucosal injury may impair the mucosal barrier function of the oesophagus allowing food allergens to enter the subepithelial layer and induce eosinophilic inflammation in the oesophagus. Oesophageal motility disturbances are common after OA-TOF repair, which could result in prolonged exposure to potential allergens in the already-damaged mucosa thereby increasing the risk of local sensitization to potential food allergens. Prolonged exposure to anti reflux acid suppressive medication from birth in OA-TOF children may also potentially increase the risk for allergic sensitization to food allergens.

Identifying EoE in OA-TOF patients is integral to management, as EoE can present with similar symptoms as reflux, and long-term complications of untreated EoE include dysphagia, food impaction and strictures. In our study, compared to OA-TOF patients without EoE, OA-TOF patients with EoE had a significantly higher incidence of symptoms of vomiting, dysphagia, strictures and gastrostomy for feeding difficulties.

Diagnosis of EoE in OA-TOF patients is similar to that in the general population and requires the presence of >15 eosinophils/High Powered Field in oesophageal biopsies. Multiple esophageal biopsies need to be taken in keeping with standard guidelines for diagnosis of EoE, as EoE is a patchy disease process, and also because, on endoscopy, the typical endoscopic findings of EoE - namely furrows and white exudates - may not be seen in all OA-TOF patients.

There is no evidence that the treatment and management of EoE in EA patients should be different from other children. Therefore current recommendations for treatment of EoE (six food elimination diet, elemental feeds, swallowed topical steroids- Fluticazone or Budesonide slurry) in the general population should be followed in OA-TOF patients. A follow up study from our group at SCH looking at efficacy of treatment of EoE in the OA-TOF population found an improvement, not only in histology, with a significant reduction in the intraepithelial eosinophil count, but also in symptoms of dysphagia (swallowing difficulties), reflux, prevalence of strictures, and need for dilations.