Disclosed is a conduit (4) comprising a conduit wall defining a flow channel through which a fluid may flow and a plurality of further channels (24) through at least part of the conduit wall. Each further channel (24) comprises a first end (20) and a second end (22). The first ends (20) of the further channels (24) are spaced apart along a length of the conduit (4) and comprise openings in fluid communication with the flow channel of the conduit (4). The second ends (22) of the further channels (24) are located proximate to one another (e.g. substantially collocated) such that the distance between the second ends (22) of any two further channels (24) is smaller than the distance between the first ends (20) of those two further channels (24). Pressure sensors (26) may be coupled to the second ends (22) of the further channels, which may be closed.