Supernatant Information and Courses from MediaLab, Inc.
These are the MediaLab courses that cover Supernatant and links to relevant pages within the course.
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| Which of the following characteristics are present if blood is due to brain hemorrhage? | View Page |
| Bloody Specimen When blood is present in a CSF specimen, it is necessary to determine whether the blood is due to a traumatic puncture or to a pathologic condition. There are several clues to help make this distinction:
Traumatic tap:More blood is present in tube 1 than in tubes 2, 3, or 4.When sample is centrifuged within one hour, supernatant is clear.Blood clots on standing.Subarachnoid or cerebral hemorrhage:Blood is evenly distributed in all tubes.When sample is centrifuged within one hour, supernatant is pink or yellow.Blood does not clot on standing. | View Page |
| Xanthochromia Samples from patients who have suffered a subarachnoid hemorrhage or cerebral hemorrhage may have a pink- to yellow-tinged supernatant when the sample is centrifuged within one hour after collection.
The term used to describe the colored supernatant is xanthochromia. The color varies according to the substance causing the color and the length of time after the incident that the sample is examined.
| View Page |
| An Example of Xanthochromia Two to four hours after a subarachnoid hemorrhage, the supernatant of a CSF sample will be pale pink to pale orange.
The source of this color is oxyhemoglobin from lysed red cells present in the CSF before the puncture. Xanthochromia from the lysed red cells reaches its peak 24 - 36 hours after the hemorrhage and gradually disappears after four to eight days.
In the same type of hemorrhage, after 12 hours yellow xanthochromia begins to appear due to the presence of bilirubin. The bilirubin is the breakdown product of oxyhemoglobin from the original lysed red cells.
The yellow color in the supernatant reaches its peak in about two to four days and disappears after two to four weeks. | View Page |
| Important Aspects of Xanthochromia It is important to recognize that xanthochromia is the appearance of color in the supernatant of a fresh, centrifuged CSF sample.
There are a variety of causes for the appearance of this color. Therefore, it is important that xanthochromia be reported.
The physician is responsible for determining the reason for its presence. | View Page |
| Which of the following situations indicate a clot is most likely due to a traumatic tap? | View Page |
| Reverse Typing Reverse typing refers to the testing of a patient's serum for the presence of ABO antibodies. The patient's serum is mixed with known red cells in a test tube. A specified number of drops of patient serum are placed into each of three properly labeled tubes. A specified number of drops of known A1 cells are added to the A tube, and a specified number of drops of known B cells are added to the B tube. The tubes are mixed by gently shaking, centrifuged, and observed against a well-lit white background for the presence of hemolysis in the supernatant fluid. The cell button is then gently dispersed and inspected for agglutination, again using a well-lit background. Hemolysis or agglutination is a positive reaction. The expected reactions can be seen in the table on the following page. | View Page |
| Steps in Preparing a Concentrated Urine Sediment Mix urine specimen well, and transfer 10-15 ml of urine to conical centrifuge tube. Centrifuge at 1500 rpm for 10 minutes. Decant supernatant, and resuspend sediment in 0.5-1.0ml of residual specimen. Place a drop of concentrated sediment on a glass slide and coverslip. | View Page |