Adjuvant Adenoidectomy for the Treatment of Chronic OME in Children

Inclusion Criteria: * 1\. Children 4-12 years of age. * 2\. Diagnosed with chronic OME. Diagnostic criteria: I. Middle ear effusion detected by otoscopy; II. Type B or C tympanograms; III. Symptoms/signs of OME persisted for \>3 months; * 3\. Documented hearing loss ≥20dB (average threshold of 500Hz, 1000Hz and 2kHz in pure tone audiometry). * 4\. Adenoid hypertrophy (A/N ratio\> 0.5 in lateral radiography of the nasopharynx). * 5\. Informed consent given by the patients and their guardians. Exclusion Criteria: 1. Cleft palate or other systemic disorders. 2. Patients are diagnosed with other nose, sinuses or ear diseases that are eligible for surgical treatment. 3. Patients are diagnosed with OSAHS, tonsil hypertrophy ≥II° or scheduled for tonsillectomy. 4. History of tympanostomy tube placement. 5. Infection of the upper respiratory tract or acute rhinosinusitis over the past 7 days. 6. Sensorineural hearing loss. 7. Other situations that the investigators find unsuitable for the trial.