Comparison of the Anvajo Vet Fluidlab 1 urine sediment analyzer to manual microscopy and Idexx SediVue analysis for analysis of urine samples from cats and dogs

Abstract

The Vet Fluidlab 1 (Anvajo), a new urine sediment analyzer for use in veterinary medicine, uses holographic microscopy to detect urine sediment particles in uncentrifuged urine. We compared the performance of the Fluidlab to manual microscopy and Idexx SediVue analysis for the detection of RBC, WBC, epithelial cells (EC), struvite crystals (STR), all crystals (CRY), and casts (CST) in urine samples from cats and dogs. The performance of the Fluidlab for the detection of bacteria was compared to bacterial culture. We included 624 urine samples from feline (238; 38%) and canine (386; 62%) patients; 227 samples had been submitted for bacterial culturing. The sensitivity of the Fluidlab compared to manual microscopy was 92.1% for RBC, 90.1% for WBC, 87.5% for EC, 67.6% for STR, 53.9% for CRY, and 12.5% for CST. Specificity was >97% for STR and CST, 90.0% for CRY, 78.4% for WBC, 59.4% for EC, and 55.1% for RBC. Sensitivities and specificities of the Fluidlab for analytes compared to manual microscopy were found to be similar to those obtained by the Fluidlab compared to SediVue analysis. Miscellaneous materials (e.g., lipid droplets, sperm, cell detritus) seemed to be the main reason for the high false-positive rate in RBC and EC classification by the Fluidlab. Detection of bacteria by the Fluidlab compared to bacterial culture had a sensitivity of 89.8% and a specificity of 72.3%. The performance of the Fluidlab is acceptable for the detection of WBC and bacteria; sensitivity for the detection of CRY and CST, and specificity for the detection of RBC and EC, require improvement.

Die Urinuntersuchung bei Hund und Katze, Teil 1: Physikalische und chemische Urinuntersuchung

“…Die Zellzahlen im Urinsediment können innerhalb von 2 h bereits signifikant abnehmen [22]. Eine in-vitro-Bildung von Struvitoder Kalziumoxalat-Dihydrat-Kristallen kann bereits innerhalb weniger Minuten auftreten [20,[24][25][26]. Ist das Vorkommen von Kristallen von besonderem Interesse für den Untersucher, muss die Urinsedimentuntersuchung sofort (innerhalb weniger Minuten nach Uringewinnung) erfolgen [3,26].…”

Die Urinuntersuchung bei Hund und Katze, Teil 2: Urinsedimentanalyse

“…Durch präanalytische Schritte kann es zu Ergebnisschwankunen kommen: Bei der Zentrifugation kommt es häufig zu unvorhersehbaren Zellverlusten und Zerstörung von fragilen Partikeln wie z. B. Zylindern [14,18]. Die Entfernung des Überstands und die Resuspension des Sediments in die verbleibende Flüssigkeit stellen ebenso potenzielle Fehlerquellen dar [19,20].…”

“…Sie bringt eine große Zeit-und Personalersparnis mit sich [14,19,25,29,35,[37][38][39][40]. Weiterhin werden präanalytische Schritte und die Interpretation der Ergebnisse standardisiert, wodurch die Präzision der automatischen Geräte höher ist als die Präzision der manuellen Urinsedimentanalyse [14,26,35,[38][39][40]. Tiermedizinische Geräte wurden vor allem in den letzten Jahren entwickelt und evaluiert [14,19,26,28,35,37,[39][40][41][42][43].…”

Analytical performance evaluation of two automated urine sediment analysers using two levels of commercially available quality control material

“…2022, Seigner et al . 2022). Instrument manufacturers provide minimal quality specifications and an independent investigation evaluating in‐clinic automated urine sediment analysers using quality specifications has not been published (Lepage et al .…”

“…ASVCP guidelines recommend that the high and low amounts of microscopic elements observed over 10 fields should be reported, or that a 0 to 3+ or 0 to 4+ (semiquantitative) grading system may be used (Arnold et al 2019). Although multiple studies have evaluated automated urine sediment analysers designed for human samples, to date only a few studies have evaluated the accuracy of a urine sediment analyser in the veterinary setting or reported the sensitivity and specificity of Analyzer S for specific cellular and formed elements when compared with manual microscopy (Ince et al 2016, Laiwejpithaya et al 2018, Hernandez et al 2019, Yalcinkaya et al 2019, Vasilatis et al 2021, Blanco et al 2022, Seigner et al 2022. Instrument manufacturers provide minimal quality specifications and an independent investigation evaluating in-clinic automated urine sediment analysers using quality specifications has not been published (Lepage et al 2006, Lem & Rosenfeld 2018.…”