An apparatus for measuring pressure of fluid in a shunt includes a distensible member arranged adjacent to a graduated scale. The shunt includes a shunt valve and the apparatus is attachable to, or incorporated into the shunt at a location either at the shunt valve or upstream of the shunt valve. Both the distensible member and the scale include radiopaque markers. The fluid in the shunt acts directly on the distensible member and the distensible member is distensible in the direction of the scale.

A sensor device, at least for measuring a fluid pressure, has a base body and has a fibre optic sensor unit which includes one or more sensor elements(s) which is in the form of a light conducting fibre and which extends along a longitudinal extension of the base body at least substantially helically around the base body. A transmission unit, which is arranged in at least one measuring range around the base body and the one or more sensor elements(s), receives a fluid from an environment and transmits a fluid pressure to the sensor unit for a deformation of the at least one sensor element.