A thrombic modulator was a medical instrument used by Starfleet medical personnel as early as 2374. A conical shaped device, it is used to change the coagulation ratio of blood within the body, most likely to prevent thrombosis.

In 2374, the EMH Mark II asked The Doctor to hand to him a thrombic modulator while treating a Romulan that had taken over command of the USS Prometheus. (VOY: "Message in a Bottle")