Key points for diagnosis
The clinical manifestations of chronic suppurative otitis media differ from one another according to the classification of the types.
1. Simple type
(1) Main symptoms and signs: Pyorrhea of the affected ear is intermittent and profuse. Whenever infection of upper respiratory tract occurs, pyorrhea will appear or the quantity of pus will increase. The pus is mucous or sticky, generally free from odour. 
(2) Local examination: The perforation of the tympanic membrane lies in the tense part and is of different sizes. But there exists partial residual tympanic membrane around the perforation which is called central perforation. Through the perforated tympanic membrane, the examiner can see slightly red or pale or mildly thickened mucosa inside the tympanic cavity.
(3) Physicochemical examination. Audiometry finds conduction deafness of the affected ear; X-ray film of the mastoid process or CT scan of the temporal bone. Mastoid process is free from damage of substance of bone.

2. Carious type
(1) Main symptoms and signs: Pyorrhea is persistent inside the ear. The pus is sticky and thick often with foul odour or with granulation and polyp. The pus is intermingled with blood if there exists bleeding.

(2) Local examination: The perforation of tympanic membrane is the large perforation of the tense part, or marginal perforation. The so-called marginal perforation refers to the fact that a part of the margin of perforation of tympanic membrane has already reached the tympanic groove where there is no residual tympanic membrane. Through the perforation of the tympanic membrane, the examiner can see the granulation and polyp inside the tympanic cavity. If the polyp has the peduncle, the polyp will stick out through the perforation to obstruct the external auditory canal and hinder the drainage.

(3) Physicochemical examination : Audiometry proves conduction deafness or mixed deafness; X-ray film of the mastoid process or CT scan of the temporal bone. The examiner can see the shadow of the soft tissue inside the tympanic  cavity,  antrum  tympanicum  and  mastoid process, with possible mild damage of substance of bone.

3. Cholesteatomatous type 
(1) Main symptoms and signs: Pyorrhea is persistent and its quantity may be profuse or scanty. The pus contains the substance like bean dregs with special foul smell.There exists no history of pyorrhea inside the ear in a small number of cases of acquired primary cholesteatoma. All the patients suffer from severer conduction deafness in general. Sometimes, cholesteatoma of middle ear may form false union between the interrupted audiotory ossicles. In this case, audiotory loss is not very serious. At the late stage, pathological changes will involve cochleae, giving rise to mixed deafness.

(2) Local examination: The perforation of the tympanic membrane lies in the flaccid portion or the posterosuperior part of the tense region. Through the perforation of the tympanic membrane, the examiner can see the pale squamous substance or the indefinite-formed substance like bean dregs, with foul smell inside the tympanic cavity. In a small number of cases, the examiner can see the defect of the posterosuperior wall of the external audiotory canal.

(3) Physicochemical examination: Audiometry shows mixed deafness in most cases. X-ray film of the mastoid process or CT scan of the temporal bone. The examiner can see the damaged region of the substance of bone of the upper tympanic cavity, antrum tympanicum or mastoid process. The margins of the damaged region of substance of bone are mostly dense and uniform, which are the holes formed by cholesteatoma.