Sterile Pyuria: A Diagnostic Challenge

Pyuria is defined as having 10 or more white cells per cubic millimeter in a urine specimen, a positive Gram's stain result on an unspun urine specimen, or a positive leukocyte esterase  dipstick test. When white blood cells are consistently found in the urine without any bacteria present, it is known as sterile pyuria and can be diagnosed using aerobic laboratory procedures.  But the diagnosis may be made more difficult by the fact that it is linked to casts, proteinuria, and haematuria.

For clinicians and the allied healthcare team, sterile pyuria can provide a significant diagnostic difficulty. The foundation for making an accurate diagnosis and providing the right course of therapy is a solid clinical history, a methodical approach, a comprehensive examination, and the relevant investigation. But frequently, there is no discernible reason. 

It is not unusual to discover sterile pyuria in clinical settings. Sterile pyuria is discovered in 9% of patients who visit their physician with lower urinary symptoms and are suspected of having urinary tract infections. The general practitioners would mostly retest urine when they encountered sterile pyuria in the community. If the results were positive once more, they would begin antibiotic therapy and then send the case for additional investigation.

Sterile pyuria is frequently underestimated, yet it is a serious condition that should not be ignored. This demographic is frequently overlooked. The patient's best course of action in this case is a multidisciplinary strategy and a referral to a specialized centre.

References:

1. Wise GJ, Schlegel PN. Sterile pyuria. N Engl J Med. 2015 Mar 12;372(11):1048-54.

2. Glen P, Prashar A, Hawary A. Sterile pyuria: a practical management guide. Br J Gen Pract. 2016Mar;66(644):e225-7.
3. Goonewardene S, Persad R. Sterile pyuria: a forgotten entity. Ther Adv Urol. 2015 Oct;7(5):295-8. 

4. Dieter RS. Sterile pyuria: a differential diagnosis. Compr Ther. 2000 Fall;26(3):150-2.