from a VSA perspective, an upthrust is an individual bar which has moved higher during the period, but closed poorly, right down near the periods lows.
(I say period, because it depend which timeframe you are working im...eg - daily, weekly, monthly, intraday.....)
An Upthrust is generally a confirming sign of previous weakness, but on really high volume can be a serious sign of weakness in itself.
and from a wyckoff perspective, an upthrust is where price moves up and over a potential resistance line, but fails to stay above it, and falls back.
It can be a nice place initiate a short position.
Finally, the exact mirror image opposite to a VSA upthrust, is a shakeout.
And the exact mirror image opposite to a Wyckoff upthrust is a spring.
