Quoting from the Medical Education newsgroup's FAQ:
•••quote:•••
7.2a) What is an internship?
In the old days, all physician completed a one year "rotating
internship" after graduating from medical school. Such an
internship consisted of all the major subdivisions of medical
practice: Internal medicine, surgery, obstetrics and gynecology,
etc. The idea was to provide a broad spectrum of training to allow
the new physician to work in the community as a "general
practitioner."
Today, the closest thing we have to the rotating internships of old
is the "transitional year," also completed after graduating from
medical school. For a few specialties, a year of post-gradute
training is required before beginning a residency in that field.
Many who want to go into these fields fill that requirement with a
transitional year. Fields that require a year before beginning
residency include radiology, neurology, anesthesiology, and
ophthalmology.
In the current lingo, the first year of post-graduate training is
called "internship," and any medical school graduate in the first
year of post-graduate training is called an "intern" regardless of
what that first year of training consists. Most specialties do not
require a transitional year, but instead accept medical school
graduates straight out of medical school.
7.2b) What is a "preliminary" year? A "categorical" year?
An alternative to the transitional year for some is the "preliminary
year." Preliminary years come in two flavors, internal medicine and
surgery. Each of these preliminary years somewhat resembles the
rotating internships of old, but with a focus on either internal
medicine or surgery. Those programs that require a year of
post-graduate education before beginning residency may accept either
a transitional year or a preliminary year. Obviously, surgical
residencies will require that you do a preliminary surgery year
while some other specialties will prefer a preliminary medicine
year.
The other reason that a new M.D. would go into a preliminary year or
transitional year would be because he didn't match into the
specialty of his choice. The hopeful applicant then takes a
preliminary or transitional year in the hopes of improving his
chances and qualifications for the next year's residency match.
The term "categorical" is used largely to distinguish between the
interns who are doing a preiminary year and those who are already
accepted into the residency program. For instance, a general
surgery program may have 6 interns every year, but two of them may
doing surgery as a preliminary year. Those positions that are
already accepted into the whole surgical residency program are
called "categorical."
••••
