Cerebrospinal fluid Information and Courses from MediaLab, Inc.
These are the MediaLab courses that cover Cerebrospinal fluid and links to relevant pages within the course.
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| Where does most cerebrospinal fluid originate? | View Page |
| What is Cerebrospinal Fluid? Cerebrospinal fluid (CSF) is a clear, plasma-like fluid which circulates around the outside of the brain, in cavities within the brain (ventricles) and in the space surrounding the spinal cord. | View Page |
| Location of CSF Most cerebrospinal fluid originates in the choroid plexus. The choroid plexus is composed of a mass of tiny blood vessels which are located in the third lateral and fourth ventricles.
The remaining CSF, about 30%, is formed in other sites such as the subarachnoid space and the ependymal lining of the ventricles.
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| Three Main Functions of CSF Cerebrospinal fluid has three main functions:CSF protects brain and spinal cord from trauma.CSF supplies nutrients to nervous system tissue.CSF removes waste products from cerebral metabolism.
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| CSF Specimen Collection Process The cerebrospinal fluid sample is obtained by a physician usually via lumbar puncture in the L3-L4 region.
The opening pressure is first measured (nl 90-180 mm of water in lateral position) and if it is elevated greater than 200 mm, no more than 2 ml of CSF should be withdrawn. Sterile technique is always used to reduce the risk of infection. Care must be taken to avoid injury to neural tissue.
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| Specimen Labeling and Transport The cerebrospinal fluid sample should be properly labeled with the tube number, patient's name and hospital number.
The samples should be transported to the laboratory immediately.
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| Safety Precautions Important safety precautions must be observed when handling cerebrospinal fluid.
The following guidelines apply:Semi-automatic micropipettes and disposable plastic chambers are the safest option for CSF testing. Many laboratories still use the hemacytometer with disposable pipets.If disposable materials are not used, soak contaminated reusable pipets, hemacytometer and coverslip in 70% alcohol or Wexide.All disposable items should be placed in a biohazard container for appropriate disposal.Wash hands thoroughly when the examination is completed.Spinal fluids which are to be discarded must be placed in biohazard containers for appropriate disposal.Careful attention to specimen processing and handling will help ensure that accurate results are obtained.
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| Normal Characteristics Normal cerebrospinal fluid has the following characteristics:colorlessclearno clot presentspecific gravity of 1.006 - 1.008pH 7.3When the specimen is received in the laboratory, the macroscopic examination is performed immediately. The specific gravity examination may be optional in some laboratories.
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| Causes of Xanthochromia in Premature Infants Xanthochromia may also be present in the cerebrospinal fluid of premature infants. Reasons for this include:
elevated bilirubin in the bloodimmaturity of the blood-brain barrierelevated protein in CSF
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| WBC Correction for Traumatic Tap A calculation is used to correct CSF WBC counts which are falsely increased due to a traumatic tap:
WBCs added = WBC(blood) x RBC(CSF) / RBC(blood)The blood WBC count is multiplied by the ratio of the cerebrospinal fluid RBC count to blood RBC count.The result is the number of artificially introduced WBCs. The true CSF white cell count is then calculated by subtracting the artificially introduced WBCs from the actual CSF WBC count.
If the patient's peripheral WBC and RBC counts are within normal limits, some laboratories use the following formula:
Subtract one white cell from the CSF WBC count for each 750 RBC counted in the spinal fluid.
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| Stained Cytospin Preparations of CSF All white cells present in a cerebrospinal fluid must be identified.
If more than 10 cells/mm3 are present or there is difficulty identifying the few cells that are present, make a cytospin, a filtration, or a sedimentation preparation, stain with Wright-Giemsa, and perform differential count.
Cytospins made with a cytocentrifuge are preferred since they are easiest to make and interpret, but filtration and sedimentation methods can also be used to prepare a slide for subsequent staining.
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| Cells Seen in CSF Cells that may be seen in cerebrospinal fluid may be divided into four categories:mature peripheral blood cellsimmature hematopoietic cellstissue cellsmalignant cells
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| Which of the following would be considered normal for a glucose level in cerebrospinal fluid: | View Page |
| When three tubes of cerebrospinal fluid are received in the laboratory they should be distributed to the various laboratory sections as follows: | View Page |
| Which of the following is not considered a potentially infectious body fluid for transmitting HIV? | View Page |
| Potentially infectious body fluids These substances are considered potentially infectious for an occupational exposure: blood cerebrospinal fluid synovial fluid pleural fluid peritoneal fluid pericardial fluid amniotic fluid any body fluid visibly contaminated with blood semen or vaginal fluid tissues removed during surgery. | View Page |
| Spread of HBV in the community(2) Body fluids most likely to transmit HBV are: Blood Semen Vaginal Secretions Pleural Fluid Peritoneal Fluid Pericardial Fluid Cerebrospinal Fluid Synovial Fluid Amniotic Fluid Saliva in dental procedures Any fluid visibly contaminated with blood | View Page |
| Identification of bacteria Identification of bacteria in direct smears may be of lifesaving importance. For example, a rapid diagnosis of bacterial meningitis, made after examining a gram stained smear of the patient's cerebrospinal fluid, allows the physician to begin treatment immediately.The appearance of bacteria on gram stained smears is suggestive of a certain species, but identification may not be made on the basis of the stain alone. An exception to this rule is the presence of gram negative intracellular diplococci from a male urogenital specimen, which is presumptive identification of Niesseria gonorrhoeae.In addition, culture results can be correlated with the direct smear report.
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