Urinalysis – An Important Screening Tool

Urine chemistry comprises the majority of the urinalysis market and is broadly used with limited differentiation between products. Traditional urine microscopy is done routinely, though the manual process is time-consuming and requires a trained medical technician to characterize particles and cells based on their morphology. In order to reduce labor and time, many laboratories perform manual urine microscopy only in response to results from an initial urine chemistry test despite evidence that urine microscopy can provide a more reliable clinical diagnosis.

Need for automation
Routine urine particle analysis typically involves a number of manual steps including centrifugation, re-suspension, microscopy, and finally manual documentation of the results. These numerous steps can make the process time-consuming, laborious, and at risk of subjective and transcription errors.

Limitations of manual microscopy are:

• Low reproducibility
• Time consuming
• Variability of results between medical technologists
• Variability of results between laboratories
• Remaining elements in the supernatant after centrifugation
• Standardization not yet realized

Urinary tract infections (UTIs) are among the most common infections treated by community healthcare centers and hospitals. Urine samples constitute a large proportion of the samples tested in clinical microbiology laboratories. The gold standard for UTI diagnosis is bacterial culture, which is based on bacterial counts and identification. Culturing of the samples is fairly time- and labor-consuming, and most of the samples yield no growth or insignificant growth. In order to improve the efficiency of handling of urine samples, methods for screening out the culture-negative samples from the culture-positive samples have been developed. Chemical screening with strips for nitrite, pH, leukocytes, erythrocytes, albumin, and glucose is widely used but a meta-analysis of literature has shown that the method is insensitive and is suitable as a rule-out test only when both nitrite and leukocyte esterase are negative.

Cells, particles, and microorganisms in urine can be examined by microscopic-urine-sediment analysis, but this method is time-consuming, labor-intensive, and sensitive to inter-observer variability. Pyuria with bacteria predicts bladder infection better than the presence of bacteria alone and, therefore, a screening method that detects both leukocytes and bacteria is favorable for the identification of patients with urinary tract infections.

During the last 10 years, the use of flow cytometry-based analyzers that measure quantitatively both leukocytes and bacteria have made their presence felt.

Advanced solution for automation of urinalysis
Fluorescence flow cytometry – a proven technology used in five-part differential cell counters since a long time, offers laboratories with a breakthrough in standardization and automation of urinalysis.

Immediate analysis on native urine without the need for pre-treatment enhances laboratory workflow, reduces turnaround time, and allows skilled technologists to devote their time to other laboratory priorities.

Urine flow cytometry uses semiconductor laser technology for the analysis of the formed elements in urine. Superiority of fluorescence flow cytometry gives information as described in the table.

These systems have been further developed, especially in terms of the most frequent findings in urinalysis; and this advanced technology excels in the following:

• • Providing shortest turnaround time and Improving workflow efficiency
  • Reliably selecting out normal samples
  • More sensitive detection of samples with indications of urinary tract infections
  • Better detection and differentiation of hematuria (isomorphic and dysmorphic RBC)
  • Precise and accurate bacteria count that helps in screening samples for cultures
  • Attaining standardization in urinalysis that complies with ISLH guidelines by analyzing un-centrifuged native urine samples
  • Complete automation with quality control and traceability

Future of urinalysis
There are many laboratories opting for national and international accreditations, wherein running controls daily, storage of patient data and record of results, play an important role. The advanced technology gives additional information thus enhancing clinical value.
Use of total automation in urine chemistry and urine sediment will bring about quality Urinalysis results into labs and brings standardization in urinalysis testing, impacting patient care as a whole.