An obturator is disclosed as being of a throwaway, single use, structure, preferably fully formed of thermoplastic, polymeric material and with a piercing and cutting end defined by non-planar faces having depressions formed therein to present cutting edges. The depressions are shaped by compound curves...http://www.google.com.au/patents/US5057082?utm_source=gb-gplus-sharePatent US5057082 - Trocar assembly
