McCoy about to remove the shrapnel and cauterize Spock's wound
Cauterization was the process of applying heat to a wound in order to close it and stop the bleeding.
Phaser beams could cauterize wounds. (ENT: "Demons")
Osmotic eels were sometimes employed in the process of cauterization. In 2151, Doctor Phlox sedated an injured Jonathan Archer while the eel cauterized his wound. (ENT: "Broken Bow")
In 2152, Phlox told a crewman he would have to wait for the eel to cauterize his wound as several patients were ahead of him in line, or, as Phlox put it, the eel was "getting quite a workout today." (ENT: "Minefield")
Susan Khouri's 2155 death report revealed that she lost 1.24 liters of blood, despite the cauterizing effect of the phaser beam. (ENT: "Demons")
In 2263 of the alternate reality, Leonard McCoy used a heated piece of metal from a crashed swarm ship to cauterize Spock's shrapnel wound, eliciting a yell from the Vulcan. (Star Trek Beyond)
In 2368, Beverly Crusher instructed a medic to use a tool to cauterize the tissue of an injured member of the USS Denver's crew. (TNG: "Ethics")