CONTAMINANTS URINE

Contaminants or other constituents Extraneous contaminating materials of many types can make their way into urine specimens, especially those collected by free catch in the courtyard or the barns. Owners may sometimes collect specimens in containers that are less than clean, let alone sterile. Striving for optimal collection and transport of specimens will help maximize useful results and minimize confusing findings. Specimens mailed to laboratories without refrigeration or preservatives are subject to microbial overgrowth, whether contaminants or pathogens. Refrigeration is perhaps the best all-around method for preserving a specimen.

Cells Information Fecal parasites Fecal material, including eggs of intestinal parasites, sometimes contaminates voided urine samples. For example, the images on the left show a urine sediment of a cat stained with Sedi-stain. In the upper panel is a low magnification view showing a packet of eggs. In the lower panel, higher magnification reveals the internal structure of the hexacanth embryos of Dipylidium caninum, a tapeworm. Environmental fungi Mold spores come in a variety of shapes, sizes and colors Shown here is a brownish Alternaria spore surrounded by amorphous crystals and a few lipid droplets.Alternaria is a dematiaceous fungus that is ubiquitous in the environment Fibers Cotton, plant, and paper fibers may mimic parasite larvae or urinary casts Microbial overgrowth Shown here is a dense mat of fungal hyphae in canine urine which wasseveral days in transit. Since fungal infection of the urinary tract in dogs is quite uncommon, the odds are that this represents overgrowth of contaminants. Bacteria, whether pathogens or contaminants, can multiply when analysis is delayed. This often clouds interpretation of the sediment examination and culture results. Mucus Mucus can be observed in some urine samples, particularly that collected from horses (hence it is a constituent and not a contaminant). Mucus is far more infrequent in urine samples from other species Strands of mucus can mimic hyaline casts, particularly when viewed under regular light microscopy (upper panel on left) Compared to casts: Mucus is more irregular in shape and has irregular borders with tapered ends. Pollen Pollen grains are generally round to oval and some have a yellow to brown tint. They are most likely to be confused for parasitic ova. A good knowledge of the actual appearance of the few true parasite eggs that can occur in urine is easier to achieve than specific recognition of all types of pollen and mold spores. Again, optimizing specimen collection and handling will reduce the chances of seeing potentially confusing structures. Starch crystals (Biosorb) Lubricant in surgical and examination gloves Common contaminants in urine sediments and cytology smears. Variable in size, round to polygonal in shape, colorless, refractile (due to their crystalline nature) and usually have a circular or Y-shaped "dot" in the center (arrow in image on left).

Source : © Cornell University