Serious soft tissue infections in the spectrum of rapidly progressive necrosis of the fascia and subcutaneous tissue represent a clinical challenge in emergency department clinical practice. Fournier's gangrene (FG) is a presentation thereof that compromises the urogenital area. A low threshold of clinical suspicion complementary to laboratory evaluation and imaging is necessary to act rapidly and perform diagnostic and therapeutic surgical intervention for this condition. The present study reported the case of a 63-year-old woman who was admitted with buttock skin changes for 72 h. The diagnostic impression was septic shock due to FG. Point-of-care ultrasound (PoCUS) was performed, indicating free fluid in the muscle planes, discontinuity of the muscle fascia and the presence of gas in the subcutaneous cellular tissue. The patient was taken to surgery 2 h after admission. PoCUS was indicated to have an acceptable diagnostic performance that may optimize the care of this type of patient depending on the conditions of the emergency department and the availability of other resources.