Anesthesia is a program that generally requires a transitional year prior to starting the anesthesia training. You do PGY 1 then go to Categorical Anesthesia 1 (CA1) which is PGY2.
OB, however, does not include a transitional year. The interns in OB do a lot of the non-complicated deliveries so you can't skip intern year in that program.
Good luck finding a job as hospitalist after just one year of training. Most require board certification in IM.
If you want to do anesthesia, why not just do that now?
I think by "transitional" you really mean "preliminary". could be point of confusion.
Anesthesia: 4 years residency length.
Training programs in two possible tracks:
a) 1 + 3 (1= PGY1; 3= CA1-3 aka PGY2-4)
b) 4 years straight through/categorical programs
a) can complete one year (PGY1) of
i. prelim medicine (preferred)
ii. prelim surgery (acceptable)
iii. transitional year (meh)
as long as you have the following ACGME requirement:
At least six months of the Clinical Base Year rotations
must include experience in caring for inpatients in
internal medicine, pediatrics, surgery, or any of the
surgical specialties, obstetrics and gynecology,
neurology, family medicine, or any combination of
these. In addition, there should be rotations in critical
care and emergency medicine, with at least one
month, but no more than two months, devoted to
each. Up to one month may be taken in
anesthesiology. Rotations should ensure continuity of
teaching and clinical experience. Each month of
training may be counted only once. For example, a
rotation in a pediatric intensive care unit may count as
either a month in pediatrics or a month in critical care
medicine.
Then apply to advanced three-year training CA1-3
OR
b) can apply to categorical tracks and start at PGY1 and
complete all four years congruently.
(doesn't sound like you're inclined to do so)
If your PGY-1 training does not meet ACGME floor/ICU/EM
requirements, the CA1-3 program may ask you to meet these
requirements as electives.
While I doubt you will be forced to repeat the PGY-1 year
either as a categorical applicant or in a preliminary program,
the individual programs make that determination.
Best,