Analysis of CSF and Other Body Fluids

• The following study notes cover CSF, amniotic fluid, semen, and other body fluids.

Cerebrospinal Fluid (CSF)

• CSF is produced by the choroid plexus, reabsorbed by the arachnoid villi, and circulates in the subarachnoid space.
• If the blood-brain barrier is damaged, proteins in the blood can enter the CSF more easily.
• Haptoglobin is normally found in CSF.
• Macrophages with hemosiderin granules in CSF suggest intraventricular hemorrhage.
• Myelin basic protein presence indicates demyelination, such as in multiple sclerosis.
• CSF tubes are distributed for testing in this order: Chemistry, Microbiology, Hematology.
• WBC counts on clear CSF are only performed if >200 cells are present.
• Reactive and non-reactive lymphocytes in CSF suggest viral infection.
• Oligoclonal bands presence suggests neurosyphilis.
• A web-like clot or pellicle indicates tubercular meningitis.
• Cryptococcus neoformans shows a classic starburst pattern in CSF.
• CSF samples for freezer storage should be placed in Tube 1.
• For bloody CSF samples, dilute the sample 1:10,000 for total cell counts.
• Oily appearance may suggest radiographic dye contamination.
• CSF needs to be analyzed within 1 hour of collection.
• Thin layer chromatography is used for determining the Lecithin-Sphingomyelin (L/S) ratio.

Amniotic Fluid

• Amniotic fluid tests for fetal lung maturity includes: Lecithin-Sphingomyelin (L/S) ratio and bilirubin levels.
• Fetal swallowing is not involved in the formation of amniotic fluid
• Lamellar bodies are the storage form of surfactants in amniotic fluid.
• Sphingomyelin production is constant at 26 weeks gestation.
• A dark green amniotic fluid is not consistent with Hemolytic Disease of the Newborn (HDN).
• A Liley graph is used to analyze amniotic fluid and monitors changes in absorbance at 450nm.
• The Liley graph of amniotic fluid evaluates bilirubin increases in HDN.
• Amniotic fluid contamination with maternal urine is determined by measuring creatinine levels.

Semen

• Semen analysis should be performed to confirm high maternal serum AFP
• Semen analysis measures acid phosphatase.
• Head and tail morphology determines abnormal sperm morphology
• A semen analysis should be performed when there are no sperm present after 2 months post-vasectomy.
• Eosin stain helps determine sperm viability.
• Seminal fluid analysis should include evaluation of: liquefaction, motility, and morphology.
• Normal sperm forms should be greater than 40%
• Liquefaction should normally be less than 60 minutes.
• Motility should be more than 50% after 2 hours
• Sperm viability is shown if it does not take up stain.

Other Body Fluids

• Neutrophils that have precipitated rheumatoid factor in the cytoplasm are called Ragocytes.
• Effusions caused by lesions affecting the serous membrane are malignancy.
• Peritoneal lavage is very sensitive in detecting intra-abdominal bleeding caused by trauma.
• Serum Ascites Albumin Gradient (SAAG) is recommended for characterizing hepatic exudates and transudates.
• Lymphocytes and plasma cells are insignificant in pleural fluid found in active tuberculosis infection.
• Hemothorax is differentiated from hemorrhagic exudates by using Hematocrit of the Pleural fluid
• An elevated fecal osmotic gap indicates Osmotic diarrhea.
• Basal acid output of zero is indicative of Pernicious anemia.
• Gastric collection is best collected if the patient is about to vomit and tested for Miller.
• Spiral mucoid threads are indicative of Asthma if found in sputum or lavage.
• Large, rod-shaped, gram-positive bacilli are expected to be found in normal vaginal fluid.
• Synovial fluid in gout patients exhibit elevated Uric Acid levels.
• Septic arthritis would cause cloudy yellow-green synovial fluid with >100,000 WBC count.
• Inflammatory or immune conditions are associated with Arthrocentesis in a patient with Lupus which causes cloudy yellow fluid with 2000 WBC.
• Calcium Pyrophosphate Dihydrate (CPPD) is found in synovial fluid that attacks pseudogout.
• Eosin is used to determine sperm viability.