We report a 45-year-old obese uremic female, who developed sudden and profound shock followed by cardiac arrest during the percutaneous insertion of a permanently cuffed and tunneled hemodialysis catheter under local anesthesia. Upon our rush to the scene for succor, inspection revealed that she was pale, comatose, and tachypneic, while her peripheral radial pulse was not felt on palpation. In addition to immediate airway management, setting up vital signs monitoring, aggressive fluid resuscitation, we promptly put transesophageal echocardiograph into use. Echocardiography revealed massive right hemothorax which severely compressed the right atrium and right ventricle. Right thoracostomic drainage tube was placed, from which massive blood was drained out, and her vital signs were restored rapidly. She was returned to ordinary ward after a 5 days' intensive care. We suggested that transesophageal echocardiography is valuable and potent in facilitating rapid, accurate differential diagnosis and in guiding proper management in such critical condition.