Urine Microscopy: The Burning Truth – White Blood Cells in the Urine

Pyuria, or presence of white blood cells (WBC)s in the urine, is most commonly associated with a urinary tract infection (UTI), but a UTI is not the only cause of pyuria. Isolated pyuria in the absence of bacteriuria can represent many inflammatory processes in the urinary tract, anywhere from the glomerulus to the urethra, or even the genital tract. It is important for the provider to understand reasons for the presence of pyuria, as treatment of its associated conditions can range from outpatient observation to urgent nephrectomy. This chapter will discuss nuances of the analysis of pyuria in the context of clinical presentation to develop an appropriate differential diagnosis. Initial evaluation and management of urinary tract infection, sterile pyuria, genitourinary tuberculosis, and urinary tract fistulae will be discussed.