Urinary Eosinophils Commonly Found After Bladder Surgery

Urine samples are examined for the presence of eosinophils, which are used to screen for acute interstitial nephritis (AIN).

Patients with urinary diversion surgeries such as ileal conduit surgery, frequently have an unusually high number of urinary eosinophils, a specific kind of white cell.

At the Mayo Clinic (Rochester, MN, USA) technologists examined urine samples from three cohorts with 20 patients in each group. In the first group, urinalysis samples were with a “stoma” source indicating a previous ileal conduit surgery; in the second group the urine samples had been clinically submitted for eosinophil quantification; and for the third cohort, randomly selected urinalysis samples was performed where there was with a minimum of 1-3 leucocytes per high-powered field. Urinary eosinophils were quantified after Hansel staining as the mean of independent counts by four technologists who did not know the source. Hansel stain is used to detect eosinophils in urine or other body fluids, the eosinophils staining red against a background of blue.

In the stoma group, eosinophils composed an average 19% of the urinary white cells even though none had a clinical suspicion of AIN. In contrast, only 3.5% and 4.6% of the urinary leucocytes were eosinophils among patients with clinically ordered eosinophiluria testing and in a random sample of patients with pyuria, respectively. Importantly, 18 out of 20 (90%) of the stoma patients had greater than 5% eosinophils, meeting the criterion for a positive test.

The authors concluded that patients with a previous ileal conduit surgery have markedly elevated urinary eosinophils, far in excess of typical patients with pyuria or those with clinically ordered eosinophiluria testing. Therefore, urinary eosinophils are not a useful screen for AIN in patients after ileal conduit surgery. Acute interstitial nephritis is an immunologic adverse reaction to certain drugs, often sulfonamide or methicillin. Acute renal failure, fever, rash, and proteinuria are characteristic of this condition. The study was published in the November 2011 edition of the journal Clinical Chemistry and Laboratory Medicine.

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