An aspect provides a method of metering flow through a fluid conduit having an obstruction therein, including: placing an obstruction body within the conduit; generating at least two differential pressure measurement signals using at least three different pressure ports, said at least three different pressure ports comprising: an upstream pressure port; a downstream pressure port; and an auxiliary pressure port; wherein at least one of the upstream pressure port, the downstream pressure port, and the auxiliary pressure port is positioned at an angle between 0 and 90 degrees with respect to a conduit wall; establishing a baseline relationship between the at least two differential pressure measurement signals; and determining if the baseline relationship between the at least two differential pressure measurement signals differs by a predetermined amount. Other aspects are described and claimed.