Chronic Serous Otitis Media

Anatomy & Pathophysiology:

Otitis media with effusion (OME) is defined as the presence of a middle ear effusion without acute inflammation, distinguishing it from acute otitis media (AOM). The effusion may be mucoid or serous in nature; the disease entity is therefore sometimes referred to as chronic serous otitis media (CSOM). In the pediatric setting, OME is most commonly seen in patients with a history of recurrent AOM, where the inflammatory symptoms have resolved, but an effusion persists between or after infections. The pathogenesis of OME likely involves multiple factors; however, the predominant cause is thought to be Eustachian tube dysfunction. Negative pressure in the middle ear generated by poor drainage via the Eustachian tube leads to either a transudative or exudative process, in which an effusion is produced. Children are more prone to AOM and OME because their Eustachian tubes are shorter and more horizontal than those of adults. Additionally, the presence of adenoid hypertrophy in many pediatric patients further impairs Eustachian tube function by obstructing its opening into the nasopharynx. Children with congenital craniofacial anomalies that further impact the anatomy of the Eustachian tube (e.g., trisomy 21) are particularly prone to otitis media. Other factors that may contribute to OME include the presence of bacterial biofilms, allergy, and viral infection.


Because OME is frequently asymptomatic and may resolve without treatment, accurate epidemiologic data is difficult to obtain. Prior studies have found incidences as high as 60% among children ages 2-6 years. As with AOM, the incidence of OME is thought to decline significantly past the age of 7, once Eustachian tube function begins to mature toward the adult level. The exception is in patients with craniofacial abnormalities, who may continue to have OME into adulthood.

Natural History:

The likelihood of self-resolution without treatment depends on the duration that the effusion has been present. Some degree of effusion is usually present immediately after an episode of AOM. In general, spontaneous resolution within 1 month is seen in over 60% of cases. However, in patients who have had a middle ear effusion for greater than 3 months, the chance of spontaneous resolution at 1 year is only 25%.


Unlike AOM, OME has few associated signs and symptoms. Because of the lack of acute inflammation, patients do not typically experience pain or fever. The most common presenting symptom is hearing loss, which is often brought to attention due to lagging school performance or language development. Some children may also complain of a blocked feeling in the ear or experience problems with balance.

Differential Diagnosis of Otitis Media with Effusion:

  • Causes of Conductive Hearing Loss
    • Cerumen impaction
    • Foreign body
    • External canal exostoses or tumors
    • Tympanic membrane perforation
    • Tumors (cholesteatoma, hemangioma)
    • Ossicular chain abnormalities (e.g., malleus ankylosis, otosclerosis)
  • Causes of Middle Ear Effusion
    • Eustachian tube dysfunction (immaturity)
    • Craniofacial anomalies resulting in Eustachian tube dysfunction
    • Nasal obstruction caused by adenoid hypertrophy, nasopharyngeal tumor, inflammation, or infection.
    • Allergies


Physical Examination

Diagnosis of OME is made by pneumatic otoscopy, which demonstrates a minimally mobile or immobile tympanic membrane due to presence of effusion in the middle ear. The tympanic membrane is often opaque or may be retracted and an air-fluid level or bubbles in the middle ear space are sometimes present.

In rare cases of persistent unilateral OME, particularly in the absence of a history of AOM, a flexible fiberoptic nasopharyngeal exam should be performed to rule out other causes of Eustachian tube obstruction such as nasopharyngeal tumors.

Audiologic Studies

An age-appropriate technique for audiometry quantifies the degree of conductive hearing loss (CHL) when considering treatment options. OME generally causes CHL in the mild to moderate range.


Because the natural history of OME is spontaneous resolution in many cases, observation is an option. Intervention is generally considered for symptoms persisting longer than 3 months if audiometry reveals a significant hearing loss or if there is evidence of functional impact (such as speech delay or inability to hear at school). The mainstay of treatment for OME is myringotomy with placement of tympanostomy tubes. Specifics regarding this procedure are given in Tympanostomy and Tube Placement. Studies have shown that myringotomy alone is ineffective for treatment of OME. The addition of adenoidectomy may provide further benefit if the patient has concurrent symptoms suggestive of adenoid hypertrophy (e.g., nasal obstruction, hyponasal voice) or documented enlarged adenoid pad on examination.

Pharmacologic treatments are not currently recommended for OME. Use of a hearing aid may be considered as an alternative to surgical intervention, particularly in patients with trisomy 21.

Complications, Prognosis & Follow-Up:

The majority of children need only one set of ventilation tubes as their Eustachian tube dysfunction improves with increasing age. Some children require multiple sets of ventilation tubes, occasionally long-term. Complications associated with AOM may involve spread of infection to surrounding structures and are addressed in the corresponding chapter. Complications of OME mostly impact development as a result of hearing loss or vestibular and balance issues. These symptoms are temporary and resolve when the effusion is no longer present.

Key Points

  • Otitis media with effusion (OME) is the presence of a middle ear effusion without acute inflammation.
  • The predominant cause of OME is Eustachian tube dysfunction.
  • Diagnosis of OME is made by pneumatic otoscopy, which demonstrates reduced mobility of the tympanic membrane.
  • Persistent unilateral OME warrants an endoscopic nasopharyngeal exam to rule out Eustachian tube obstruction due to tumor.
  • Surgical intervention for OME is considered if persistent significant hearing loss is present on audiogram, or if the patient is at high risk for, or currently exhibits signs of, speech or language delay.