The Collaborative International Dictionary of English v.0.48:

Cystotomy \Cys*tot"o*my\ (s??s-t?t"?-m?), n. [Gr. ???? bladder +
   ???? to cut: cf. F. cystotomie.]
   The act or practice of opening cysts; esp., the operation of
   cutting into the bladder, as for the extraction of a
   calculus.
   [1913 Webster]