I say, and with God's success: Istinja (the act of cleansing after relieving oneself) becomes an innovation (bid'ah) if something comes out from other than the two passages (the front and back), or if wind comes out from the back; in this case, one does not perform istinja, and if one does, it would be considered an innovation. This is because istinja is recommended for every impurity that comes out from the two passages and has a visible form: such as feces, urine, semen, prostatic fluid, pre-ejaculatory fluid, and blood; because istinja is for purification by reducing the impurity. If the impurity that comes out from the two passages has a visible form, there is a need for purification by reduction, and there is no istinja for wind; because it does not have a visible form. Refer to: Al-Tawdeeh Sharh Muqaddimah Abi Al-Layth 94/b, Bada'i Al-Sana'i 1/18, and Al-Ikhtiyar 1/48, and God knows best.