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Synovial fluid examination


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Synovial fluid examination

  1. 1. Synovial Fluid Examination Presented By: Nasir Nazeer
  2. 2. Introduction Synovial fluid is a viscous, non-Newtonian fluid found in the cavities of synovial joints. With its yolk-like consistency, the principal role of synovial fluid is to reduce friction between the articular cartilage of synovial joints during movement. The inner membrane of synovial joints is called the synovial membrane and secretes synovial fluid into the joint cavity The fluid contains hyaluronic acid secreted by fibroblast-like cells in the synovial membrane and interstitial fluid filtered from the blood plasma. This fluid forms a thin layer (roughly 50 μm) at the surface of cartilage and also seeps into micro-cavities and irregularities in the articular cartilage surface, filling all empty space. During movement, the synovial fluid held in the cartilage is squeezed out mechanically to maintain a layer of fluid on the cartilage surface (so-called weeping lubrication).
  3. 3. Functions of Synovial Fluid Reduction of friction - synovial fluid lubricates the articulating joints. Shock absorption - as a dilatant fluid, synovial fluid is characterized by the rare quality of becoming more viscous under applied pressure; the synovial fluid in diarthrotic joints becomes thick the moment shear is applied in order to protect the joint and subsequently, thins to normal viscosity instantaneously to resume its lubricating function between shocks. Nutrient and waste transportation - the fluid supplies oxygen and nutrients and removes carbon dioxide and metabolic wastes from the chondrocytes within the surrounding cartilage.
  4. 4. Reasons for Synovial Fluid Examination Joint aspiration may be performed to diagnose and assist in the treatment of joint disorders and/or problems. By analyzing the fluid obtained during the procedure, the following conditions may be determined:    Gout Various types of arthritis Joint infection Joint aspiration can also be performed to remove a large collection of fluid around a joint. Sometimes bursitis (inflammation of the bursa) causes fluid to collect in a joint. Removing the fluid will decrease the pressure, relieve pain, and improve movement of the joint. Sometimes, a medication is injected into the joint following removal of the fluid to help treat tendonitis or bursitis.
  5. 5. Risks involved in Synovial fluid Aspiration As with any surgical procedure, complications can occur. Some possible complications may include, but are not limited to, the following:     Discomfort at the aspiration site Bruising at the aspiration site Swelling at the aspiration site Infection at the aspiration site
  6. 6. Precautions before aspiring Synovial Fluid Doctor should explain the procedure to the patients and offer the opportunity to ask any questions that they might have about the procedure. Laboratory staff should also guide the patient about the test and procedure of drawing the sample. Patients are asked to sign a consent form that gives permission to do the procedure. The laboratory staff should notify if patient is sensitive to or are allergic to any medications, latex, tape, and anesthetic agents (local and general). The laboratory staff should also notify all medications (prescribed and over-the-counter) and herbal supplements that the patients are taking. The laboratory staff should also note if the patient have a history of bleeding disorders or if patient is taking any anticoagulant (bloodthinning) medications, aspirin, or other medications that affect blood clotting. It is necessary to stop these medications prior to the procedure. Generally, no prior preparation, such as fasting or sedation is required.
  7. 7. During Synovial Fluid Aspiration A joint aspiration may be performed on an outpatient basis. Procedures may vary depending on patient’s condition. Generally, a joint aspiration procedure follows this process        Patient should be positioned so that the doctor/technician can easily reach the joint that is to be aspirated. The skin over the joint aspiration site should be cleansed with an antiseptic solution. If a local anesthetic is used, patient will feel a needle stick when the anesthetic is injected. This may cause a brief stinging sensation. The doctor/technician will insert the needle through the skin into the joint. Patient may feel some discomfort or pressure. The doctor/technician will remove the fluid by drawing it into a syringe that is attached to the needle. The needle will be removed and a sterile bandage or dressing will be applied. The fluid sample is sent to the lab for examination.
  8. 8. After Synovial Fluid Aspiration Once sample is drawn, it is important for the patient to keep the joint aspiration site clean and dry. The aspiration site may be tender or sore for a few days after the joint aspiration procedure. Take a pain reliever for soreness as recommended by the doctor. Aspirin or certain other pain medications may increase the chance of bleeding. Be sure to take only recommended medications. The patient should be guided to report to the doctor in any of the following conditions after fluid aspiration procedure:    Fever Redness, swelling, bleeding, or other drainage from the aspiration site Increased pain around the aspiration site
  9. 9. Specimen handling and collection Synovial fluid is present in all joints but usually it is collected from the knee joint. Normal amount of fluid contained in the knee cavity is less than 3.5mL; however this amount increases in joint disorders. The sample collected is dependent upon amount of fluid build up in the joints. Normally samples are collected in three tubes.    EDTA tubes – for Cell count and differentials Heparinized tubes – Chemical and Immunologic tests Sterile tubes – Crystal examination and Microbiological testing
  10. 10. Laboratory Tests of Synovial Fluid Following are the tests performed of Synovial joints fluid. Gross examination for color and clarity Appearance    Clear and light yellow – Normal Turbid or cloudy – elevated cell count, crystals, cartilage debris Bloody Hemorrhagic fluid – homogenously bloody Traumatic aspirate – streaks of blood  Color – varies based on bacterial infection, cell or crystal presence Leukocyte count and differential (Place sample under a microscope, count the number of red and white blood cells, and then looks for crystals (in the case of gout or bacteria) Measure glucose, proteins, uric acid, and lactic dehydrogenase (LDH) Culture the fluid to see if any bacteria grows
  11. 11. Classification of Synovial Fluid Normal Noninflammatory Inflammator y Septic Hemorrhagic Volume (ml) <3.5 >3.5 >3.5 >3.5 >3.5 Viscosity High High Low Mixed Low Clarity Clear Clear Cloudy Opaque Mixed Color Colorless/stra w Straw/yellow Yellow Mixed Red WBC/mm3 <200 <2,000 5,00075,000 >50,000 Similar to blood level Polys (% <25 <25 50-70 >70 Similar to blood level Gram stain Negative Negative Negative Often positive Negative