The word patient originally meant 'one who suffers'. This English noun comes from the Latin word patiens, the present participle of the deponent verb, patior, meaning 'I am suffering,' and akin to the Greek verb πάσχειν (= paskhein, to suffer) and its cognate noun πάθος (= pathos).
An outpatient (or out-patient) is a patient who is hospitalized for less than 24 hours. Even if the patient will not be formally admitted with a note as an outpatient, they are still registered, and the provider will usually give a note explaining the reason for the service, procedure, scan, or surgery, which should include the names and titles and IDs of the participating personnel, the patient's name and date of birth and ID and signature of informed consent, estimated pre- and post-service time for a history and exam (before and after), any anesthesia or medications needed, and estimated time of discharge absent any (further) complications. Treatment provided in this fashion is called ambulatory care. Sometimes surgery is performed without the need for a formal hospital admission or an overnight stay. This is called outpatient surgery. Outpatient surgery has many benefits, including reducing the amount of medication prescribed and using the physician's or surgeon's time more efficiently. More procedures are now being performed in a surgeon's office, termed office-based surgery, rather than in a hospital-based operating room. Outpatient surgery is suited best for healthy patients undergoing minor or intermediate procedures (limited urologic, ophthalmologic, or ear, nose, and throat procedures and procedures involving the extremities).
An inpatient (or in-patient), on the other hand, is "admitted" to the hospital and stays overnight or for an indeterminate time, usually several days or weeks, though in some extreme cases, such as with coma or persistent vegetative state patients, stay in hospitals for years, sometimes until death. Treatment provided in this fashion is called inpatient care. The admission to the hospital involves the production of an admission note. The leaving of the hospital is officially termed discharge, and involves a corresponding discharge note.
Misdiagnosis is the leading cause of medical error in outpatient facilities. Ever since the National Institute of Medicine’s groundbreaking 1999 report, “To Err is Human”, found up to 98,000 hospital patients die from preventable medical errors in the U.S. each year, government and private sector efforts have focused on inpatient safety. While patient safety efforts have focused on inpatient hospital settings for more than a decade, medical errors are even more likely to happen in a doctor’s office or outpatient clinic or center.