A device for invasively measuring fluid pressure is disclosed. The device includes a disposable housing having a fluid contacting area and a non-fluid contacting area. A disposable diaphragm in a substantially non-elastic state is disposed within the housing and separates the fluid contacting area from the non-fluid contacting area. A side of the diaphragm is adapted to contact the fluid, and the diaphragm has sufficient flexibility to move a distance axially within the non-fluid contacting area in response to fluid contact. The distance is substantially proportional to the fluid pressure. An electronic sensing device is removably attached adjacent the non-fluid contacting area of the housing, and is spaced from the diaphragm. The electronic sensing device is capable of determining the fluid pressure.