Contaminant Information and Courses from MediaLab, Inc.
These are the MediaLab courses that cover Contaminant and links to relevant pages within the course.
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| A voided urine specimen is delivered from the women's clinic to the laboratory six hours after collection. The following results are reported: Color: yellowProtein: negativeBilirubin: negative Clarity: cloudyGlucose: negativeUrobilinogen: 0.2 mg/dL Sp. Gravity: 1.020Ketone: negativeNitrite: positive pH: 9.0Blood: negativeLeukocyte esterase: negativeWhat might these results indicate? | View Page |
| False Positive Results A false positive result for blood on the reagent strip can occur when oxidizing contaminants, such as hypochlorite (bleach), remain in collection bottles after cleaning. Contamination of the urine with provodine-iodine, a strong oxidizing agent, used in surgical procedures can result in a false positive reaction. Microbial peroxide found in association with urinary tract infections may also cause false-positive results. Capoten® (Captopril) can cause decreased reactivity. The muscle tissue form of hemoglobin, myoglobin is a well-known cause of false-positive reactions on the blood portion of the reagent strip. When tissue hemoglobin is present, the urine specimen has a clear red appearance. Patients suffering from muscle-wasting disorders or muscular destruction due to trauma, prolonged coma, or convulsions or individuals engaging in extensive exertion may have myoglobin in their urine. Specific tests for myoglobin, such as immunodiffusion techniques or protein electrophoresis, are needed to confirm the presence of this substance in a urine specimen. Levels of ascorbic acid normally found in urine do not interfere with this test. | View Page |
| False Positive Results A false positive nitrite test result may occur when a urine specimen has remained at room temperature for an extended period of time, allowing bacterial contaminants to multiply and produce measurable levels of nitrites. Interference from some medications that cause the urine to become red or orange may lead to an incorrect reading of positive for nitrite. | View Page |
| The elements indicated by the arrows are more likely to be seen in patients with which condition: | View Page |
| Which of the following cells when found upon microscopic examination of the urine would be most indicative of kidney disease: | View Page |
| The fungus illustrated in this photomicrograph was recovered from an induced sputum specimen from a 74 year old man with chronic obstructive pulmonary disease. This isolate is most likely: | View Page |
| Of the following dematiaceous fungi, the black, suede-like colony illustrated here, reaching no larger than the size of a dime after 7 days incubation, most likely can be identified as: | View Page |
| The dematiaceous colony illustrated here grew to a diameter of 3 - 4 cm in 5 days. The dematiaceous fungus that can be ruled out is: | View Page |
| The disease with which the dematiaceous fungus illustrated in this photomicrograph is most likely associated is: | View Page |
| This photomicrograph is an acid-fast stained smear prepared from a yeast colony growing on ascospore agar. A helmet-shaped, red-staining, acid fast yeast cell is seen in the center of view at the tip of the arrow, against the background, blue-staining blastoconidia. The presumptive identification of Hansenula anomala was made. Predisposing conditions that may indicate that this isolate is more than a contaminant include: | View Page |
| Contaminated Gram Stain Solution Contamination of the staining solutions rarely occurs, but should be suspected when smears repeatedly contain the same organisms, and these organisms do not grow or are inconsistent with the clinical picture. Yeast and gram negative rods can occur as stain contaminants. | View Page |
| Yeast Yeast can appear as single cells or in the budding form. As single cells they can be confused with RBCs because they are about the same size. In the budding form, yeast is easily identified as demonstrated on this slide. Yeast can be found in patients with cystitis due to yeast, usually candida, or as a vaginal contaminant from patient's with vaginal candidiasis. | View Page |
| Bacteria Bacteria may also be present, especially during a urinary tract infection. This view shows bacteria as solid gray rods or cocci. Since bacteria may also be a contaminant in specimens remaining at room temperature, or due to an unclean catch, caution must be observed in reporting bacteria. If 20 organisms per hpf are seen, the bacteria are considered to be clinically significant. | View Page |
| Introduction In this topic certain miscellaneous structures found in the urinary sediment will be discussed. These structures include: Parasites Sperm Fat bodies Mucus External contaminants | View Page |
| Parasites Parasites which may be found in urinary sediments include Trichomonas vaginalis, Enterobius vermicularis and Schistosoma haematobium. It is also important to note that parasites and parasitic ova may be seen in urine sediments as a result of fecal or vaginal contamination. This slide shows examples of Trichomonas vaginalis. In the female, Trichomonas is usually found as a contaminant from vaginal infection and is often accompanied by an increase in the number of white cells. Trichomonas is highly motile, measuring 5 - 15 microns with a characteristic pear shape. It has multiple anterior flagella and the nucleus is often apparent. | View Page |
| Starch Granules Some starch granules from dusting powders have faint concentric striations, others do not. External contaminants (ie. those that enter the urine specimen during collection, transportation, or while being examined on the slide) must be differentiated from crystals and other clinically significant findings. | View Page |
| Contaminants and Artifacts There are several contaminants and artifacts which must be identified. This slide shows a fiber. Fibers may occur in any specimen from clothing, diapers, lint, toilet paper or lens paper. They are usually longer and wider than casts and have more distinct edges. Striation and blunt ends are distinguishing features of fibers. | View Page |