Well, it would have to be a precise entry point to predict, as you do, that blood should have been spurting all over the place. The neck maybe a “very vascular area” but where the bullet struck obviously makes all the difference as to whether there would be copious effusions of blood or not. In addition, there seems to be equally reliable (which is to say not) reporting that the bullet struck her in the chest.
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.