Hospital operator Tenet Healthcare Corp posted quarterly earnings on Tuesday that were more than double the average analyst forecast, as it treated more patients, and its shares rose 6 percent. The third-largest U.S. hospital chain said the number of patients treated in specialties including trauma, neurosurgery, oncology and vascular surgery was especially strong. Patient volumes at U.S. hospitals in general have remained sluggish due to high unemployment that has left many without health insurance to pay for medical treatment. More people also have sought emergency care out of necessity. Jefferies analyst Art Henderson said he doesn't foresee a rebound in overall hospital visits anytime soon but noted Tenet's out-patient trends are surpassing its rivals.