Acute discharge (lasting less than 6 weeks)

Acute otitis media with perforated eardrum

Severe ear pain significantly relieved when a thick, whitish discharge starts

Doctor’s examination alone

Chronic otitis media (acute flare up)

History of eardrum perforation and/or cholesteatoma (a noncancerous growth of skin cells in the middle ear), and previous discharge

Eardrum appears abnormal during doctor's examination

Sometimes doctor’s examination alone

Sometimes high-resolution temporal bone CT

Cerebrospinal fluid leak caused by severe head injury or recent neurosurgery

Obvious recent head injury or neurosurgery

Fluid ranges from crystal clear to blood

Imaging studies such as head CT scan including skull base or MRI with gadolinium

Otitis externa (infectious or allergic)

Infectious: Often after swimming or injury; severe pain, worse with pulling on ear

Allergic: Often after use of ear drops; more itching and redness, and less pain than with infectious cause

Typically a rash on the earlobe, where discharge trickled out of ear canal

Both: Ear canal very red, swollen, and filled with debris; eardrum appears normal

Doctor’s examination alone

Chronic discharge (lasting more than 6 weeks)

Cancer of ear canal

Discharge often bloody, mild pain

Sometimes doctor can see a growth in ear canal

Typically in older people

Removal and examination (biopsy) of ear tissue

Usually CT scan or MRI

Chronic otitis media

History of ear infections and typically eardrum perforation and/or cholesteatoma

Less pain than with external otitis

Eardrum appears abnormal during doctor's examination

Sometimes doctor’s examination alone

Usually culture of a sample of the ear discharge

If suspected cholesteatoma, MRI

Foreign object

Usually in children

Drainage foul-smelling, pus-filled (purulent)

Foreign object often visible during examination unless visibility blocked by swelling and/or discharge

Doctor’s examination alone

Mastoiditis

Often fever, history of untreated or unresolved otitis media

Redness, tenderness over mastoid

Usually a doctor’s examination alone

Sometimes CT scan

Necrotizing external otitis

Usually people have an immune deficiency or diabetes

Chronic severe pain

Swelling and tenderness around ear, abnormal tissue in ear canal

Sometimes weakness of facial muscles on affected side

CT scan or MRI

Usually culture