they can use any blood sample collected.
but if we assume that all cases where 1 sample is collected from the athlete is urine, and cases wheres its 2 as 1 blood 1 urine, then the number of blood collections is relatively low.
At the moment it looks like blood collection on the whole is being restricted to the top tier fighters. For example, snippet of the last few weeks.
Cruz, Alvarez, Werdum likely had blood collected, the rest, just urine (its an assumption but a fair assumption)
like the regular testing will take a while to roll out. From 20 samples a week, to 30, 50 and now 70 samples a week being collected, from just the main card at events being tested to entire cards, things are steadily progressing. At the moment, probably just the top handful of fighters have bio passport profiles, but eventually will be rolled out to everyone.