  We investigate QCD sum rules for vector currents in the rho meson channel in
the nuclear medium. For increased sensitivity, we subtract out the vacuum
contributions. With a saturation scheme often considered in the literature, we
find these subtracted sum rules to be unstable. It indicates the importance of
other contributions neglected in the saturation scheme. These include more
Landau singularities at low energy, additional operators in the medium, and
possibly the in-medium width of the rho meson.
