What is a common feature of tongue lacerations?

A common feature of tongue lacerations is blanching under pressure. When tissues are injured, especially in the case of a laceration, they may show signs of blood loss in the affected area. Blanching occurs when pressure is applied to a darkened or bruised area, causing it to temporarily lose its color. This is indicative of local vascular response and can help assess the severity of the injury.

In considering the other choices, while constant pain may be present, it is more subjective and can vary widely from person to person based on pain tolerance, the location of the laceration, and associated injuries. Visible swelling could occur but isn't a defining characteristic of lacerations specifically, as not all lacerations lead to significant swelling. Necrosis, on the other hand, indicates tissue death that is not a common immediate feature of typical tongue lacerations; it would only occur in severe cases where blood supply is significantly compromised and requires time to develop. Thus, blanching under pressure stands out as a readily observable, distinct feature of tongue lacerations.