Haematuria is the presence of blood in the urine. Haematuria can be macroscopic (i.e. it is visible), and the urine is then coloured in red, pink or brown and sometimes contains blood clots. It can also be microscopic: the urine is then of normal colour, the blood being detected only on microscopic examination. Several diseases can cause haematuria, including urinary tract infections (cystitis), tumours and papilloma of the bladder, but also kidney damage during lupus.