You obviously don’t understand the meaning of effusion.
In medical terminology, an effusion refers to accumulation of fluid in an anatomic space, usually without loculation. Specific examples include subdural, mastoid, pericardial and pleural effusions.
Neck wounds spurt. There is no effusion.
Nice semantic dodge. Here’s Webster: 3. “the escape of a fluid from anatomical vessels by rupture or exudation.” In other words, spurting.
Neck wounds that include damage to veins and arteries spurt. Neck wounds that don’t don’t spurt.