A 6-year-old child presents with severe otalgia, fever (38.5°C), and conductive hearing loss for 3 days. Otoscopy reveals a bulging, hyperemic tympanic membrane with loss of landmarks. The child has no history of ear discharge. Which investigation is most appropriate to confirm the diagnosis of acute suppurative otitis media and guide further management?

Explanation

## Diagnosis of Acute Suppurative Otitis Media ### Role of Tympanometry in ASOM **Key Point:** Tympanometry is the investigation of choice for confirming acute suppurative otitis media, particularly in the pre-perforation stage when the tympanic membrane is intact but under tension. ### Why Tympanometry? Tympanometry measures middle ear compliance and pressure by introducing a probe tone at 226 Hz and varying air pressure in the external auditory canal. In acute suppurative otitis media: - **Type B curve** (flat tympanogram) = absent or severely reduced compliance, indicating fluid/pus accumulation in the middle ear - **Negative middle ear pressure** = retraction of the tympanic membrane due to Eustachian tube dysfunction - **Non-invasive and painless** = ideal for pediatric patients - **Objective documentation** = provides baseline for monitoring resolution ### Tympanometry Findings in ASOM | Finding | Interpretation | | --- | --- | | Type A curve (normal) | Normal middle ear pressure and compliance | | Type B curve (flat) | Middle ear effusion or high stiffness (ASOM) | | Type C curve | Negative middle ear pressure (Eustachian tube dysfunction) | | Type Ad curve | Hypercompliant middle ear (ossicular discontinuity) | **Clinical Pearl:** In the acute phase with bulging tympanum, tympanometry is more reliable than otoscopy alone for quantifying middle ear dysfunction and serves as an objective baseline for follow-up. **High-Yield:** Tympanometry does NOT require patient cooperation for hearing responses (unlike audiometry) and is the gold standard for objective assessment of middle ear status in children with suspected ASOM. ### Why NOT the Other Options? - **Pure tone audiometry**: Requires patient cooperation and active response; cannot be reliably performed in young children; documents hearing loss but does NOT confirm the diagnosis of ASOM - **High-resolution CT temporal bone**: Reserved for complications (mastoiditis, intracranial spread, facial nerve involvement); not indicated for uncomplicated ASOM - **X-ray mastoid (Schuller's view)**: Outdated; poor sensitivity for early mastoiditis; not used for diagnosis of ASOM in modern practice