Hematuria, or the presence of red blood corpuscles in the urine, is a symptom of very frequent occurrence, and its etiology is manifold. In this paper, the term hematuria is used in the broad sense, as including not only gross hemorrhage but also the presence of red blood corpuscles in the urine demonstrated microscopically.
Certainly, with very rare exceptions, the presence of blood in the urine is always a symptom of some lesion in the genito-urinary tract. When hematuria is due to systemic disease that does not primarily affect the urinary organs, the principle also holds true, since there is usually some anatomic change to cause the bleeding. Whatever the nature of the disease, the basic causes of the blood loss are the direct result of congestion, infection or trauma, including that due to the development of abnormal tissue, or actual changes in the blood that alter factors associated with