A Physician Assistant (PA) is a nationally certified and state-licensed medical professional. PA's provide health care with the supervision of a physician. They are trained to provide diagnostic, therapeutic, and preventive health services. They take medical histories, examine patients, order and interpret laboratory tests and x-rays, and make diagnoses. They also treat minor injuries by suturing, splinting, and casting. In 47 states, PA's may prescribe medications under the supervision of a physician. Many PA's work in primary care areas such as general, internal medicine, pediatrics, and family medicine. Others work in specialty areas such as general and thoracic surgery, emergency medicine, orthopedics, and geriatrics. PA's specializing in surgery provide pre- and post-operative care and may work as first or second assistants during major surgery.