Many patients are told that they have “water in their ears” after visiting a doctor for secretory otitis media, so they speculate that water has gotten into their ears by taking a bath or swimming accidentally. For normal people, the outer ear canal is a blind tube, which means that it is a dead end, and the end is closed by the eardrum, so even if you take a bath, wash your hair or swim, water can only remain in the outer ear canal. Secretory otitis media causes fluid in the middle ear, which means that the fluid exists in the middle ear on the inner side of the eardrum, not in the outer ear canal, so it is not caused by the inflow of fluid from outside. When the eustachian tube is blocked, air cannot enter the middle ear cavity, and the air retained in the middle ear is gradually absorbed by the mucosa, lowering the air pressure, causing the tympanic membrane to sink in, capillaries to dilate, and serous exudate to accumulate in the middle ear cavity, resulting in exudative otitis media. Therefore, the middle ear effusion in secretory otitis media is extracted from the surrounding tissues by the negative pressure of the middle ear. Of course, according to some recent findings, there may be exudation caused by infections with low-toxicity pathogens among them. In short, fluid in the middle ear is not caused by washing the hair, bathing or swimming with water in the ear before it dries.