  We study the Fermi surface topological transition of the pocket-opening type
in a two dimensional Fermi liquid. We find that the paramagnetic fluctuations
in an interacting Fermi liquid typically drive the transition first order at
zero temperature. We first gain insight from a calculation using second order
perturbation theory in the self-energy. This is valid for weak interaction and
far from instabilities. We then extend the results to stronger interaction,
using the self-consistent fluctuation approximation. Experimental signatures
are given in the light of these results.
