Phase-contrast Information and Courses from MediaLab, Inc.
These are the MediaLab courses that cover Phase-contrast and links to relevant pages within the course.
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| Hyaline Casts Hyaline casts are the type most commonly seen in the urine sediment. A few hyaline casts may occasionally be found in normal urine, and hyaline casts may be seen after strenuous exercise, during fever, diuretic therapy. Pathologically, hyaline casts may be seen with congestive heart failure, and may be seen together with other types of casts in a variety of renal diseases. Hyaline casts have a refractive index similar to the urine in which they are suspended. For this reason, hyaline casts will appear almost invisible under brightfield microscopy, but are easily of seen by phase-contrast microscopy. | View Page |
| Microscopic Examination of Urine Sediment The sediment may be examined using both brightfield and phase-contrast microscopy. With the brightfield microscope, subdued light must be used. Some structures will be missed if there is too much light in the field. Fine focus throughout the examination to identify structures in different focal planes.
Scan the slide on low power for quantification of casts, crystals and elements that are present in only a few fields. Use high power to identify casts and count red blood cells, white blood cells and epithelial cells. | View Page |
| Phase-Contrast Microscopy Phase contrast is used to detect casts and mucus which have a very low refractive index and may be missed using brightfield microscopy. Phase contrast enhances the outlines of casts and mucus, making their detection much easier. | View Page |
| Urine Sediment Urine sediment may also contain white blood cells (WBCs). Most of the WBCs in urine are segmented neutrophils. Since it is possible that lymphocytes, monocytes, and/or eosinophils may be present, the cells in urine can be stained if it is necessary to differentiate them. The segmented neutrophil just above center of the image to the right shows a distinct nucleus. When viewing urinary sediment under the microscope, the fine focus adjustment must be used to identify white blood cells. White blood cells swell in dilute alkaline urine and the cytoplasmic granules exhibit brownian movement resulting in “glitter cells.” These cells lyse rapidly. “Glitter cells” are most easily seen when viewed under phase-contrast microscopy. | View Page |
| Sperm Under Phase-Contrast Under phase contrast the oval body of the sperm appears bright whereas the tail is dark. | View Page |
| Trichomonas under Phase-Contrast Under phase contrast, Trichomonas organisms appear much darker than the surrounding white blood cells. | View Page |
| Phase-Contrast of Enterobius vermicularis On phase contrast, the larva appears darker. Note the clear space surrounding the larva. | View Page |