Nguyen Tan Phong Educational institute: Hanoi Medical University The new conclusions of the trial: Clinical characteristics: Functional symptoms: hearing loss 100%, otorrhea 91% Physical symptoms: + Tympanic membrane perforation 62, 7%, among 85, 7% marginal perforation + Atelectasic tympanic membrane 37, 3%, 88% at IV degree All patients with hearing loss, PTA average 49, 7 ± 1, 407 dB, ABG average 35, 03 ± 1, 058 dB.