To confirm a case of oesophageal atresia, a size 10 French gauge soft rubber catheter is passed into the oesophagus through the mouth. It cannot be passed more than 10-12cm from the gums in cases of atresia. Note the practical pitfall of a smaller catheter being apparently passed but in fact coiling up, unnoticed, in the pharynx.
Investigations to confirm the diagnosis include chest and abdominal radiographs. With a tracheo-oesophageal fistula, for example, air is noted in the stomach and small intestine. It is not advisable to use contrast media because of the risk of aspiration should there be a fistula.
Chest radiology may also reveal cardiac anomalies, and an echocardiogram is probably indicated, since the surgeon needs to know that the aorta is on the correct side.