What is the clinical examination and diagnostic workup for a patient presenting with purulent (pus) discharge from the ear?

Clinical Examination and Diagnostic Workup for Purulent Ear Discharge

The diagnostic approach to purulent ear discharge centers on distinguishing between acute otitis externa (AOE), acute otitis media with perforation (AOM), and chronic suppurative otitis media (CSOM) through targeted history-taking and otoscopic examination, as these three conditions require fundamentally different treatment strategies. 1, 2

Initial Clinical Assessment

Key Historical Features

• Onset and duration: Acute symptoms (<2 weeks) suggest AOE or AOM with perforation, while persistent discharge ≥2 weeks to 3 months indicates CSOM 2, 3
• Preceding upper respiratory infection: Common with AOM, less typical for AOE 4, 5
• Water exposure or swimming: Strongly suggests AOE 1, 6
• Recent ear trauma or cleaning: Points toward AOE 6, 7
• Age: AOM peaks at 6-47 months; AOE more common in older children and adults 1, 2
• Presence of tympanostomy tubes: Suggests tube otorrhea with different microbiology 2

Critical Physical Examination Maneuvers

The single most discriminating examination finding is tragal/pinna tenderness, which when positive indicates otitis externa, while its absence suggests middle ear pathology (AOM or CSOM). 1, 2

• Tragal tenderness test: Gently pull the pinna or press the tragus—tenderness that is "often intense and disproportionate to visual findings" confirms AOE 1
• Ear canal inspection: AOE shows canal edema, erythema, and wet debris; middle ear disease shows normal canal with discharge from tympanic membrane 1, 7

Otoscopic Examination Protocol

Essential Otoscopic Findings

Before adequate otoscopic examination, aural toilet (debris removal) is mandatory, as failure to visualize the tympanic membrane leads to missed middle ear pathology. 2

• Aural toilet technique: Use microsuction, gentle dry mopping, or irrigation to clear discharge and debris 1, 2
• Tympanic membrane visualization:
  • Intact membrane with normal canal: Rules out middle ear disease 1
  • Bulging, erythematous membrane with reduced mobility: Confirms AOM 2, 4
  • Visible perforation with purulent discharge: Indicates AOM with perforation or CSOM 2
  • Cannot visualize membrane due to canal swelling: Consistent with AOE 1, 7

Pneumatic Otoscopy

• Normal tympanic membrane mobility: Suggests otitis externa 2
• Reduced or absent mobility: Indicates middle ear effusion (AOM or OME) 2
• Note: Pneumatic otoscopy is accurate in only ~80% of cases even with experienced examiners 1

Differential Diagnosis Framework

Acute Otitis Externa (AOE)

• Clinical triad: Otalgia, tragal tenderness, and ear discharge 1, 7
• Otoscopic findings: Ear canal edema, erythema, wet debris; tympanic membrane normal if visible 1, 7
• Microbiology: Pseudomonas aeruginosa (20-60%) and Staphylococcus aureus (10-70%) 1
• Treatment: Topical antimicrobial drops (quinolones preferred); oral antibiotics have limited utility 1

Acute Otitis Media with Perforation

• Clinical presentation: Recent onset following URI, fever, otalgia, then discharge after perforation 2, 4
• Otoscopic findings: Visible perforation with purulent discharge, no tragal tenderness 2
• Microbiology: Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis 1, 4
• Treatment: Non-ototoxic topical antibiotics (ofloxacin) plus systemic antibiotics based on age and severity 1, 2

Chronic Suppurative Otitis Media (CSOM)

• Defining feature: Persistent ear discharge ≥2 weeks through non-intact tympanic membrane 2, 3
• Otoscopic findings: Visible perforation with ongoing discharge, no tragal tenderness 2
• Treatment: Non-ototoxic topical antibiotics only; avoid aminoglycosides due to ototoxicity risk 2, 3

Ancillary Diagnostic Studies

When to Obtain Cultures

• Tympanocentesis: Consider when multiple antibiotic courses fail in AOM; provides definitive bacterial diagnosis 1
• Culture of discharge: Generally not needed for initial management but useful in recalcitrant cases 1
• Avoid nasopharyngeal cultures: Neither sensitive nor specific for predicting middle ear pathogens 1

Audiometry

• Not required acutely but consider if hearing loss persists after treatment resolution 4, 5
• Middle ear effusion causes average 25 dB hearing loss that may impact speech/language development 8

Imaging Studies

• Not routinely indicated for uncomplicated ear discharge 1
• CT temporal bone: Reserved for suspected complications (mastoiditis, intracranial extension) 2

Critical Pitfalls to Avoid

• Failing to perform aural toilet: Cannot accurately diagnose without visualizing the tympanic membrane 2
• Using ototoxic drops with perforation: Aminoglycosides (neomycin, gentamicin) cause cochlear damage when middle ear exposed 2, 3
• Prescribing oral antibiotics for AOE: Topical therapy superior with 77-96% cure rates versus 30-67% for systemic 2
• Missing concurrent disease: Patients with tympanostomy tubes can have both AOE and middle ear infection requiring dual therapy 2
• Overlooking referred otalgia: Normal ear examination with pain suggests TMJ syndrome, pharyngitis, dental disease, or malignancy in high-risk patients 2

Special Considerations

Patients with Tympanostomy Tubes

• Tube otorrhea microbiology: Pseudomonas aeruginosa or typical nasopharyngeal pathogens (S. pneumoniae, H. influenzae, M. catarrhalis) 2
• Treatment: Topical quinolone drops alone for 10 days maximum; avoid systemic antibiotics 2
• MRSA suspicion: Consider in recurrent or recalcitrant discharge 2

Red Flags Requiring Urgent Referral

• Severe otalgia in diabetic or immunocompromised patients: Suspect necrotizing (malignant) otitis externa 1
• Facial nerve palsy, vertigo, or severe headache: Suggests intracranial complications 2
• Granulation tissue or polyps: May indicate cholesteatoma or malignancy 2