A surgical instrument system for use in a surgical procedure is disclosed. The surgical instrument system may include an instrument configured to puncture the tissue of a patient and detect when the instrument has entered a lumen of the patient's body. Liquid may be present in the lumen or the lumen may be devoid of liquid or tissue. The instrument is configured to determine when the needle tip is engaged with a portion of patient's tissue and determine when the needle tip has exited that portion of the patient's tissue by detecting changes in properties of the tissue, specifically, electrical resistance.