  We propose to build a combinatorial invariant, called the spectral monodromy,
from the spectrum of a single non-selfadjoint h-pseudodifferential operator
with two degrees of freedom in the semi-classical limit. Our inspiration comes
from the quantum monodromy defined for the joint spectrum of an integrable
system of n commuting selfadjoint h-pseudodifferential operators, given by S.
Vu Ngoc. The first simple case that we treat in this work is a normal operator.
In this case, the discrete spectrum can be identified with the joint spectrum
of an integrable quantum system. The second more complex case we propose is a
small perturbation of a selfadjoint operator with a classical integrability
property. We show that the discrete spectrum (in a small band around the real
axis) also has a combinatorial monodromy. The difficulty here is that we do not
know the description of the spectrum everywhere, but only in a Cantor type set.
In addition, we also show that the monodromy can be identified with the
classical monodromy defined by J. Duistermaat.
