A surgical system for use in establishing and maintaining an opening to an anatomical space of a body, the system comprising an obturator assembly having a cutting portion at a distal end and a cannula, the cannula being detachably coupled to the cutting portion and deployable into the anatomical space of a patient, the cannula comprises a locking portion, and a lengthwise extendable body; a valve assembly comprising a passage for receiving the cannula, a first end for coupling to a fluid extraction device and a second end for placement external and adjacent the anatomical space; a base comprising a plate for placement on a patient external and adjacent the anatomical space, the plate has an aperture configured for receiving the obturator assembly and coupling means located about the aperture for coupling with the valve assembly; and wherein, in use, the locking portion of the cannula is configured to be retained in the valve assembly with the extendable body extended into the anatomical space to facilitate a path for fluid extraction, and wherein the cannula comprises means for retaining the cannula in its extended state.