Point-of-care ultrasound (POCUS) is an important tool for clinical diagnosis and decision-making in critical and non-critical scenarios. Dyspnea, chest pain, and shock are conditions susceptible to evaluation with ultrasound considering diagnostic accuracy and clinical impact already proven. There is scarce evidence in diagnosis agreement using ultrasound as an extension of physical examination. We aimed to evaluate ED patients in whom POCUS was performed, to analyze agreement between clinical initial diagnosis using ultrasound images and final diagnosis. Furthermore, we analyze failed diagnosis, inconclusive POCUS exams, and discuss details. A cross-sectional analytical study was conducted on adults who visited the emergency department with any of these three chief complaints: dyspnea, chest pain, and shock. All were evaluated with ultrasound at admission. Agreement between initial diagnosis using POCUS and final definite diagnosis was calculated. Failed diagnosis and inconclusive exams were analyzed. A total of 209 patients were analyzed. Populations: mostly males, mean age 64 years old, hypertensive. Agreement on patients with dyspnea and suspicion of acute decompensated heart failure was 0.98; agreement on chest pain suspicion of non-ST acute coronary syndrome was 0.96; agreement on type of shock was 0.90. Among the population, 12 patients had an inconclusive POCUS exam, and 16 patients had a failed diagnosis. The use of POCUS in the emergency department shows almost perfect agreement when compared with the final diagnosis in individuals experiencing acutely decompensated heart failure, acute coronary syndrome, and shock. Prospective studies are needed to evaluate the impact of this tool on mortality and prognosis when there are diagnostic errors.