Authorities said Francisco Ayala Jr., 27, was working as a patient care technician at St. Joseph Hospital of Orange and was assigned to monitor the victim, who went to the hospital's emergency room on March 8.
Orange police Sgt. Dan Adams said Ayala allegedly attacked the woman while he was working on the night shift, March 8 into early March 9.
Adams said the victim reported the alleged attack to hospital officials who called police.
Bail has not yet been set.
The Associated Press contributed to this report.