Objective: A patulous Eustachian tube (PET) is characterized by persistent Eustachian tube patency, leading to symptoms, such as aural fullness, autophony, and audible breathing. The diagnostic criteria include both characteristic symptoms and objective findings; however, intermittent symptom presentation often prevents confirmation during clinic visits, leading to underdiagnosis. We aimed to evaluate the clinical utility of a patient-operated portable digital otoscope for confirming the diagnosis of PET. Study design: Prospective observational study. Setting: The study was conducted between January 2024 and July 2025 in a tertiary referral center. Patients: Patients with possible PET, defined by characteristic symptoms and positional improvement, but without observed tympanic membrane (TM) fluctuations during in-clinic evaluation. Intervention: Patient-operated portable digital otoscope for confirming the diagnosis of PET. Main outcome measure: Clinical utility of a patient-operated portable digital otoscope for confirming the diagnosis of PET. Results: Among 62 ears from 48 patients with possible or definite PET, 31 (50%) were initially diagnosed with definite PET. Of 24 patients (31 ears) with possible PET findings, 15 (18 ears) participated in the study. TM fluttering was detected in 8 ears in patient-operated recordings, increasing the definite PET rate from 50.0% to 62.9% (P <0.001). Conclusion: Patient-operated portable digital otoscopy significantly increased the objective confirmation of PET and addressed the diagnostic gap due to intermittent symptoms. This approach enables timely symptom-triggered TM visualization beyond clinical settings, potentially reducing diagnostic delays and unnecessary repeat visits.