orchotomy

from WordNet (r) 3.0 (2006)

orchotomy
    n 1: surgical incision into the testis to obtain material for
         analysis (as in cases of abnormally low sperm count)

from The Collaborative International Dictionary of English v.0.48

Orchotomy \Or*chot"o*my\, n. [Gr. ? a testicle + te`mnein to
   cut.] (Surg.)
   The operation of cutting out or removing a testicle by the
   knife; castration.
   [1913 Webster]