  Spin currents in a two dimensional electron gas with Rashba-type spin orbit
coupling are derived from a spin connection. Using a functional integral
method, we recover the result derived by Sinova {\em et al.}$[
\mathrm{Phys.Rev. Lett.
  92, 126603 (2004)}]$ for a uniform electric field and in the absence of
impurities. We extend this result to inhomogeneous electric and magnetic
fields. We find that non-uniform magnetic fields can give rise to spin currents
that are independent of the Rashba coupling and hence are less susceptible to
impurities than in the case of uniform electric fields.
