Haematuria
Definition of Haematuria: the presence of blood in the urine. Macroscopic (gross) haematuria: the patient has seen blood. Microscopic or dipstick haematuria: blood identified by urine microscopy or by dipstick testing, either in association with other urological symptoms - symptomatic microscopic haematuria - or during a routine medical examination (e.g. for insurance purposes) - asymptomatic microscopic haematuria. Microscopic haematuria has been variably defined as 3 or more, 5 or more, or 10 or more red blood cells (RBCs) per high-power field. Urine dipsticks test for heme (i.e. they test for the presence of haemoglobin and myoglobin in urine). Heme catalyses the oxidation of orthotolidine by an organic peroxidase, producing a blue coloured compound. Dipsticks are capable of detecting the presence of haemoglobin from 1 or 2 RBCs. False +ve urine dipstick: occurs in the presence of myoglobinuria, bacterial peroxidases, povidone, hypochlorite. False -ve urine dipstick (rare)