Four years later this is still not corrected. Etymologically, words coming from the Greek root "oi" are correctly spelled in English with Oe at the start, such as Oestrogen, Oecumenism, Oedipus and Oesophagus. Unfortunately, some American geezer decided to "simplify" American spelling but it's time you guys recognised the correct way to spell, really.
Also, please accept oesophagus - this is how it is spelt in English-speaking countries outside of the US