How can a person afflicted with enuresis differentiate between semen and urine to know when a ritual bath (ghusl) is obligatory, and does he fall under the principle of "certainty is not removed by doubt" if the matter becomes indistinguishable to him?

Semen has distinct characteristics: it is discharged with pleasure, followed by a sensation of relaxation; its odor is like that of dough or palm spathe; and its color is thick and white. Therefore, if you confirm the emission of semen, whether awake or asleep, ghusl (definition) (ritual bathing) becomes obligatory for you. Ghusl is not required merely by looking [at something unlawful], thinking [about it], an erection, or doubting the emission of semen. It is obligatory to lower your gaze from forbidden things, occupy your thoughts with what is religiously beneficial, avoid lust-inducing thoughts, and rid yourself of doubts and whispers by disregarding them.