Thursday, 28 January 2016

Automated Urine Microscopy Analysers

The use of automated system in urine analysis reduces the time and cost used in the manual routine analysis. In addition, automated system analyses a high number of samples in a short time (up to 100 samples per hour). There are a few methods available for automated system which includes the Sysmex UF1000i, Menarini sediMAX and Iris iQ200.
The Sysmex UF1000i method uses the urine flow cytometry technology to detect red blood cells, white blood cells, bacteria, epithelial cells and casts in urine. The automated system dilutes 200µL of the urine sample with citrate buffer solution and cationic surfactant with an addition of 40µL of fluorescent dye to complete the mixture. This mixture is then passed through a sheath of flow which is exposed to a laser beam to detect the particles in the stained urine sample with the fluorescent dye staining the nucleic acid in bacteria. The identification and characterisation of particles are based on the fluorescence intensity, forward scatter light and side scatter light intensity which generates electrical signal patterns by photomultiplier conversion which is then measured.
The Menarini sediMAX is an automated microscopy image based sediment analyser used in urine microscopy. The analyser produces a monolayer of urine sediment by centrifugation in a special cuvette. The sediment is analyzed by a bright field microscope and digital camera to capture and categorize 15 particle images based upon size and shape using image processing software. The digital images can be viewed by a trained laboratory staff with zoom capability. The instrument has a high sensitivity (>80%) in the detection of RBC and WBC but has a low sensitivity (approximately 50%) when compared with manual microscopy.
The Iris iQ200 method uses digital imaging and auto particle recognition to classify and quantify urine particles in uncentrifuged urine based upon size and shape. It classifies images such as WBC, RBC, bacteria, casts, yeast and crystals into categories. The digital images generated are collected, approximately 500 frames per sample, then viewed and classified by a trained laboratory staff. This is usually achieved without the use of manual microscopy.
The advantages and disadvantages of the automated urine systems (Sysmex UF1000i, SediMAX and Iris iQ200) are listed below

Sysmex UF1000i
Uses uncentrifuged urine samples.
Improved bacteria counting and flags for UTI.
Urgent urine samples can be processed by operating the analyser manually.
Throughput of 100 samples per hour.
Cannot differentiate clinically significant pathologic casts cell from benign casts.
Manual microscopy is carried out on flagged results.
This analyser does not require any reagents.
Requires minimal laboratory technician training to interpret images that are similar to manual microscopy.
Results may be available for viewing from the stored digital images
Throughput of 80 samples per hour.

Yeast is mistaken for RBCs.
Epithelial cells are mistaken for WBCs.
Particle loss may occur due to the ultracentrifugation of urine samples.
Iris iQ200
Uses uncentrifuged urine samples.
Accurately quantifies bacteria.
Results may be available for viewing from the stored digital images
Throughput of up to 101 samples per hour.
Crystals are mistaken for RBCs.
There is no sufficient resolution in order to classify all dysmorphic RBC variants which prompt manual microscopy.
Requires considerable laboratory technician training for viewing digital images that are different from manual microscopy.

No comments:

Post a Comment