Some embodiments of a medical instrument can be configured to reduce the formation of coagulum by delivering a negative charge bias to conductive surfaces that interface with blood or bodily tissue during a medical procedure. The application of the negative charge at the instrument-blood interface can reduce the fibrinogen deposition and the formation of coagulum because fibrinogen molecules in general are negatively charged at neutral pH levels. In addition, some embodiments of the instrument may be configured to irrigate the instrument-blood interface with RGD/ClfA peptides, a bicarbonate solution (or other high pH solution), or both to further repel the fibrinogen and thereby inhibit the formation of coagulum. Accordingly, some embodiments of the medical instrument can substantially reduce the risks of thromboembolism during particular medical procedures.