What does it measure?
“Pus cells” is a common report label for white blood cells seen in urine. These immune cells may appear when the urinary tract is inflamed. Microscopy counts them directly, while leukocyte esterase is an indirect chemical signal.
Before the test
- Sample
- Collect urine in the laboratory’s container, following its clean-catch instructions.
- Symptoms
- Mention burning, frequency, fever, and whether there are no urinary symptoms.
What can the result mean?
A raised count can occur with a urinary infection, but also with other inflammation or sample contamination. White cells with a negative routine culture need context; they are not an automatic reason for antibiotics. Small counts may fall within the lab’s expected interval. [1]
When is it useful, and how is it read?
Interpret the count with burning, fever, pregnancy, recent antibiotics, and culture if one was requested. White cells in someone without urinary symptoms have a different meaning from the same finding during a symptomatic illness. [1] [2]
What can affect it?
Vaginal secretions can add white cells to a sample. Recent antibiotics may affect culture results. Symptoms, pregnancy, urinary procedures, and how the sample was collected all change what the finding means. [1] [2]
Myth: «“Pus cells” always means a bacterial infection»
This familiar label means white blood cells were seen. These cells can appear with inflammation or contamination too, so the label alone does not establish the need for an antibiotic. [1] [2]
Questions you might have
Are “pus cells” the same as bacteria?
No. This usually means white blood cells seen under the microscope; bacteria are a different finding. [1] [3]
Do white cells without symptoms always need treatment?
No. White cells alone do not establish a treatable urinary infection. Pregnancy and certain procedures have specific assessment rules. [3]
What comes next?
Review the count with nitrite, esterase, symptoms, and any culture. A repeat clean-catch sample may be enough to resolve a collection issue; persistent findings or symptoms need a clinician’s assessment. [1] [2]
Do these white cells reflect an infection, another source of inflammation, or contamination?
The reference interval and units on your report are part of understanding your result. Understand units, reference intervals, and treatment targets.
Sources & references
Medical references & original research
- MedlinePlus — Leukocyte esterase
- IDSA — Asymptomatic Bacteriuria Guideline (2019)
- IDSA — Asymptomatic Bacteriuria Guideline (2019)
Books we consulted
References that informed our explanations of the test and its context.
- Pagana KD, Pagana TJ, Pagana TN. Mosby’s Diagnostic and Laboratory Test Reference. 14th ed. Elsevier; 2019.
Practical-section sources accessed: .
For general health education. Interpreting your result and deciding on tests or treatment requires your health context and a qualified clinician.
