Apparatus for use in analysing impedance measurements performed on a subject, the apparatus including a processing system operable to: a) determine first and second impedance values indicative of the impedance of at least one leg segment of the subject; b) determine an indicator using the first and second impedance values, the indicator being indicative of extracellular fluid levels in the at least one leg segment and for use in the assessment of venous insufficiency; the processing system being operable to determine the indicator by: i) determining a first indicator value with the subject in a first orientation using the first impedance value; ii) after positioning the subject in a second orientation for a predetermined time period, determining a second indicator value with the subject in the first orientation using the second impedance value; and, iii) determining the indicator using a difference between the first and second indicator values, characterised in that the processing system is operable to: (a) monitor the difference; (b) determine the time taken for the difference to fall below a reference; and, (c) provide an indication of the time taken to allow determination of a presence, absence or degree of venous insufficiency. a) determine first and second impedance values indicative of the impedance of at least one leg segment of the subject; b) determine an indicator using the first and second impedance values, the indicator being indicative of extracellular fluid levels in the at least one leg segment and for use in the assessment of venous insufficiency; the processing system being operable to determine the indicator by: i) determining a first indicator value with the subject in a first orientation using the first impedance value; ii) after positioning the subject in a second orientation for a predetermined time period, determining a second indicator value with the subject in the first orientation using the second impedance value; and, iii) determining the indicator using a difference between the first and second indicator values, characterised in that the processing system is operable to: (a) monitor the difference; (b) determine the time taken for the difference to fall below a reference; and, (c) provide an indication of the time taken to allow determination of a presence, absence or degree of venous insufficiency. i) determining a first indicator value with the subject in a first orientation using the first impedance value; ii) after positioning the subject in a second orientation for a predetermined time period, determining a second indicator value with the subject in the first orientation using the second impedance value; and, iii) determining the indicator using a difference between the first and second indicator values, characterised in that the processing system is operable to: (a) monitor the difference; (b) determine the time taken for the difference to fall below a reference; and, (c) provide an indication of the time taken to allow determination of a presence, absence or degree of venous insufficiency. (a) monitor the difference; (b) determine the time taken for the difference to fall below a reference; and, (c) provide an indication of the time taken to allow determination of a presence, absence or degree of venous insufficiency.