UA’s are wrong about 20% of the time
TLDR
In febrile children under 36 months old, who had urinalysis performed on bladder catheterized urine, about 20% of the negative UA’s were culture positive.
The Details
In this 3 center study, the records of 4188 children 1-36 months old who underwent bladder catheterization with UA and urine culture, were reviewed. Urinalysis was considered included both point of care and lab run tests. Positive urinalysis was defined as Leukocyte esterase >1+ or >5WBC/hpf on manual microscopy, which is lower than some cutoffs. They, of note, only included pyuria alone, not nitrite positive tests in this study. Positive urine culture was defined as the presence of at least 50,000 CFU/ml of a single pathogen.
They calculated sensitivity and specificity for the different cutoffs for diagnosing UTI and found that leukocyte esterase was about 84% sensitive and >5WBC/hpf was 75-90% sensitive depending on how the WBC count was obtained (digitally, flow cytometry, hemocytometer, digital imaging, or manual microscopy). Flow cytometry and manual microscopy were the most sensitive, while digital imaging and hemocytometry was the least sensitive. They found low levels of contamination with about 7% of the positive cultures thought to be from contamination or asymptomatic bacteriuria.
The Bottom Line
Get a urine culture on all these little kids you’re cathing. I think we probably all do this from a logistics perspective, but this study adds some further data as to why we should do it.
In febrile children under 36 months old, who had urinalysis performed on bladder catheterized urine, about 20% of the negative UA’s were culture positive.
The Details
In this 3 center study, the records of 4188 children 1-36 months old who underwent bladder catheterization with UA and urine culture, were reviewed. Urinalysis was considered included both point of care and lab run tests. Positive urinalysis was defined as Leukocyte esterase >1+ or >5WBC/hpf on manual microscopy, which is lower than some cutoffs. They, of note, only included pyuria alone, not nitrite positive tests in this study. Positive urine culture was defined as the presence of at least 50,000 CFU/ml of a single pathogen.
They calculated sensitivity and specificity for the different cutoffs for diagnosing UTI and found that leukocyte esterase was about 84% sensitive and >5WBC/hpf was 75-90% sensitive depending on how the WBC count was obtained (digitally, flow cytometry, hemocytometer, digital imaging, or manual microscopy). Flow cytometry and manual microscopy were the most sensitive, while digital imaging and hemocytometry was the least sensitive. They found low levels of contamination with about 7% of the positive cultures thought to be from contamination or asymptomatic bacteriuria.
The Bottom Line
Get a urine culture on all these little kids you’re cathing. I think we probably all do this from a logistics perspective, but this study adds some further data as to why we should do it.
