Urine Analysis: Part 21 – Urine For Pus cells, WBC, Eosinophils, Mononuclear cells, Pyuria
- The test sample is urine.
- To find the urinary tract infection.
WBC may originate from any part of the urinary tract.
- The size of WBC is larger than RBC around 12 µm in diameter.
- The predominant white cells are neutrophils.
- To identify the neutrophils is easy because of the granular cytoplasm and multilobate nucleus.
- These are reported an average of 10 fields under high power.
- Neutrophils lyse rapidly in alkaline urine and lose nuclear details.
- WBCs can migrate to the site of infection or inflammation.
- An increased in WBCs in urine is called Pyuria.
- The presence of WBCs in the urine indicates infection or inflammation in the urinary tract.
- There may be sterile pyuria.
Eosinophiluria is suggestive of interstitial nephritis and does not favor urinary tract infection.
- Eosinophils are also seen in drug-induced interstitial nephritis.
- Few eosinophils may be seen in urinary tract infection and renal transplantation rejection.
- Urine sediment slide is prepared by cytospin and stained with Wright’s stain or especially by Hansel’s stain.
- Percentage of >1% eosinophils in urine is significant.
Mononuclear cells like lymphocytes, macrophages, and histiocytes may be present in small numbers.
- These cells are not identified in the wet preparation.
- Lymphocytes increased number may be seen in the early stages of renal transplantation rejection.
- For mononuclear cells, the supravital stain is needed Or.
- Add acetic acid to enhance nuclear details.
- These are seen in kidney transplant rejection.
- An increased number of lymphocytes indicate early signs of kidney rejection.
- Also, plasma cells may be seen along with lymphocytes.
Symptoms of the urinary tract infection shows:
- Increased infrequent urination.
- There is blood in the urine (hematuria).
- Urine color is cloudy.
- There is a burning sensation.
Causative agents of UTI are:
- The most common is E.coli. About 80% of UTI is due to these bacteria.
- Staphylococcus is a common cause in young sexually active females.
- Klebsiella and Enterobacter are also common causative agents.
- Sometime Candida may also cause UTI.
- Evidence of pyuria :
- There is a positive leukocyte esterase test. The sensitivity is 70 to 95%.
- There is a positive nitrite test even in the fresh urine. This test specificity is quite high but sensitivity is only 50%
- There is a reagent strip that finds evidence of urinary tract infection.
- The ultimate diagnosis is culture:
- A count of 100,000 bacteria is a significant number to call it a urinary tract infection.
- A count of 10,000 bacteria is considered contamination.
- Male = pus cell(WBC) = < 4 /HPF.
- Female = pus cell (WBC) = 5 to 7 /HPF.
Increased WBCs in urine is seen in:
- Bacterial infection of the urinary tract.
- Acute Appendicitis.
- Chronic pyelonephritis.
- Bladder Tumors.
- An autoimmune disease like SLE.
- Note: When there are clumps of WBCs, these should be reported and these suggest urinary tract infection.
- In Urinary bladder infection mainly there are WBCs and very few RBCs.
Please see more details in the Urine analysis.