The centrifugal pump comprises a substantially cylindrical pump chamber 26 having an inner diameter D3, a fluid inlet 24, a fluid outlet 28 and an impeller 10 having an outer diameter (D2 fig 1) and being rotatably mounted on a driveshaft within said pump chamber . The driveshaft is rotatable by driving means to rotate said impeller in use and accelerate fluid flowing into said pump chamber through said fluid inlet and out of said fluid outlet. The inner diameter of the pump chamber D3 is substantially equal to or greater than 1.40 times the outer diameter of the impeller D2. This arrangement reduces fluidic drag whilst maintaining the required pumping pressure. Also disclosed is a portable fluid collection apparatus such as a urine leg bag having a detection means (figs 4 & 5) to measure fluid within the apparatus in either two or three separate positions. The apparatus may also comprise processor and signal means. The pump and collection apparatus may be found in a single apparatus which may be battery powered or disposable.
