If not dodged, Darius's Q will leave bleed damage on yasuo even after his shield expires which leads to more than decent trade from that alone, dodging is also a little tricky in some circumstances meaning that if there are no minions nearby, i.e: In the jungle, or if you've used the dashes through all the minions, Darius has a free ticket to pull you in, auto attack, and Q, and if he has ult, you're basically dead.
It is best to gank other lanes instead of facing your own since those kills and assists boosts your gold significantly, and you may actually be ahead of the Darius.
In your case, there are no other lanes for you to gank, so you're screwed.
(Edit: Just realized this thread was so old that darius probably had different mechanics then idk but for newcomers, read this)