Are there macrophages in the blood vessels and within the blood stream?
Usually, monocytes and neutrophils are present(there are other cells like Lymphocytes and other leukocytes), the only time a macrophage will be present is when inflammation occurs, I suspect this is due to the large size of the macrophage, it would be difficult for it to travel in the bloodstream, as it is quite big, compared to the small size of a monocyte. During inflammation, vascular dilation and permeability increase, which makes it easier for cells and proteins to diffuse across the endothelium.

A source that macrophages are present in all tissues: https://www.researchgate.net/publication/227897252_Macrophages_in_the_embryo_and_beyond_Much_more_than_just_giant_phagocytes

A source that talks about all the leukocytes and lymphocytes present in the blood normally: http://www.histology.leeds.ac.uk/blood/blood_wbc.php