We assessed the effect of focused point of care ultrasound (POCUS) used for critical nontraumatic hypotensive patients presenting to the emergency department of our hospital on the clinical decisions of the physicians and whether it led to the modification of the treatment modality. This prospective clinical study was conducted at the Emergency Department of Antalya Training and Research Hospital. Nontraumatic patients aged 18 and older who presented to our emergency department and whose systolic blood pressure was <100 mmHg or shock index (heart rate/systolic blood pressure) was >1 were included in the study. While the most probable preliminary diagnosis established by the physician before POCUS was consistent with the definitive diagnosis in 60.6% (n = 109) of 180 patients included in the study, it was consistent with the definitive diagnosis in 85.0% (n = 153) of the patients after POCUS (p < 0.001). POCUS performed for critical hypotensive patients presenting to the emergency department is an appropriate diagnostic tool that can be used to enable the physicians to make the accurate preliminary diagnosis and start the appropriate treatment in a short time.