According to statistics, after upper respiratory tract infections, about 30% of adult patients develop varying degrees of ear symptoms, most of which are secretory otitis media.

This condition is not as acutely painful as acute otitis media; it often only causes a feeling of ear fullness, mild hearing decline, autophony, or a sensation of fluid in the ear. Because the symptoms are relatively mild, many people choose to tolerate them and only seek medical attention when hearing has significantly worsened.

The Eustachian tube is a narrow canal connecting the nasopharynx and the middle ear cavity, carrying three important functions.

It regulates middle ear air pressure to balance with the external environment; drains middle ear secretions to keep the cavity clean; and prevents pathogens from the nasopharynx from retrograding into the middle ear. In a healthy state, the Eustachian tube briefly opens when we swallow or yawn to accomplish these tasks.

When a cold strikes, the mucosa of the nasal cavity and pharynx becomes congested and swollen; at the same time, inflammatory mediators also affect the mucosa of the Eustachian tube itself, causing dysfunction and preventing normal opening.

Once Eustachian tube function is impaired, the middle ear cavity becomes a closed chamber. As the oxygen in the middle ear is gradually absorbed by the mucosa, negative pressure forms in the cavity. At this point, the patient will feel a clogged, pressure-filled sensation as if the ear is being sucked.

When negative pressure persists, the middle ear mucosa will compensatorily secrete fluid in an attempt to equalize the pressure difference. These secretions are initially thin, but over time they become progressively more viscous, changing from clear fluid to glue-like consistency, and even paste.

Accumulated fluid in the middle ear cavity directly interferes with the normal vibration of the ossicular chain, causing conductive impairment. This is why patients experience a sensation of hearing loss.

If the effusion persists for more than 3 months, it is defined as chronic serous otitis media (chronic secretory otitis media). At this stage, the viscous effusion gradually organizes, forming fibrous adhesions that bind and fix the ossicles.

More seriously, long-term effusion and negative pressure can lead to tympanic membrane retraction, atrophy, and even permanent perforation. The structures within the middle ear cavity may undergo irreversible changes, and in such cases, even surgical removal of the effusion may not fully restore hearing.

If ear fullness persists for a week after a cold or other upper respiratory infection; symptoms worsen day by day; or it interferes with normal daily life and work — meeting any of these criteria should prompt consideration of medical consultation.

Parents should be especially alert: children are a high-risk group for otitis media with effusion because their Eustachian tubes are shorter and more horizontal. If a child becomes less responsive after a cold, the TV volume is turned up very high, or a teacher reports inattention in class, the ears should be examined promptly.