Infection: cystitis, tuberculosis, prostatitis, urethritis, schistosomiasis, infective endocarditis. Tumour: renal carcinoma, Wilms tumour, carcinoma of the bladder, prostate cancer, urethral cancer or endometrial cancer. Trauma: renal tract trauma due to accidents, catheter or foreign body, prolonged severe exercise, rapid emptying of an overdistended bladder (eg, after catheterisation for acute retention). Inflammation: glomerulonephritis, Henoch-Schönlein purpura, IgA nephropathy, Goodpasture s syndrome, polyarteritis, post-irradiation. Structural: calculi (renal, bladder, ureteric), simple cysts, polycystic renal disease, congenital vascular anomalies. Haematological: sickle cell disease, coagulation disorders, anticoagulation therapy. Surgery: invasive procedures to the prostate or bladder. Toxins: sulfonamides, cyclophosphamide, non-steroidal anti-inflammatory drugs. Others: genital bleeding, including child abuse; menstruation; Münchhausen s syndrome