Diagnostics

AOM is primarily a clinical diagnosis based on characteristic symptoms and otoscopic findings. Other causes of otalgia and hearing loss should be excluded. Pneumatic otoscopy or tympanometry should be used to confirm the presence of an effusion

The diagnosis of AOM can be made if any of the following features are present:

• Moderate to severe bulging of the tympanic membrane

• New onset of otorrhea not due to otitis externa

• New onset of otalgia AND mild bulging of the tympanic membrane

• Distinct erythema AND mild bulging of the tympanic membrane

Not routinely indicated; consider in severe infection or diagnostic uncertainty.

• CBC: Leukocytosis may be present.

• Gram stain and culture of middle ear fluid

  • Indication: patients who do not respond to initial therapy, acutely ill patients, and patients with immune deficiencies

  • Typically acquired through tympanocentesis: the extraction of middle ear fluid through a small-gauge needle.

  • Fluid should also be cultured if there is otorrhea from tympanostomy tubes or a perforated TM

• Blood cultures: indicated only in severe infection

• Rarely required unless there is clinical uncertainty and/or concerns of complications

• Suspected intracranial complications: MRI brain and temporal bone

• Suspected extracranial complications, e.g., mastoiditis: high-resolution CT temporal bone

• Pneumatic otoscopy

  • Description

    • A pneumatic bulb is attached to the otoscope to allow assessment of tympanic membrane mobility.

    • A seal is formed in the ear canal by the tip of the speculum, and air is forced in by pressing the bulb.

  • Indications: clinical uncertainty for AOM and to confirm the presence of middle ear effusion

  • Characteristic finding: hypomobility of the tympanic membrane

• Tympanometry

  • Description: a probe is inserted into the ear to generate sound waves and measure pressure in the ear canal

  • Indications: confirmation of middle ear effusion

  • Characteristic findings

    • High peak pressure reflecting the bulging of the tympanic membrane

    • Flattened curve indicating effusion