Synovial Fluid Analysis
General
Synonym/Acronym:
Arthrocentesis, joint fluid analysis, knee fluid analysis.
Rationale
To identify the presence and assist in the management of joint disease related to disorders such as arthritis and gout.
Patient Preparation
Refer to the study titled “Arthroscopy” for additional and detailed information regarding patient preparation. Note that there are no fluid restrictions unless by medical direction. Fasting for at least 12 hr before the procedure is recommended if fluid glucose measurements are included in the analysis. The patient may be asked to be NPO after midnight.
Regarding the patient’s risk for bleeding, the patient should be instructed to avoid taking natural products and medications with known anticoagulant, antiplatelet, or thrombolytic properties or to reduce dosage, as ordered, prior to the procedure. Number of days to withhold medication is dependent on the type of anticoagulant. Note the last time and dose of medication taken. Protocols may vary among facilities.
Normal Findings
Method: Macroscopic evaluation of appearance; spectrophotometry for glucose, lactic acid, protein, and uric acid; Gram stain, acid-fast stain, and culture for microbiology; microscopic examination of fluid for cell count and evaluation of crystals; ion-selective electrode for pH; nephelometry for RF and C3 complement; indirect fluorescence for ANAs.
Test | Normal Result | ||||||||||||||||||||||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Color | Colorless to pale yellow | ||||||||||||||||||||||||||||||||||||||||
Clarity | Clear | ||||||||||||||||||||||||||||||||||||||||
Viscosity | High | ||||||||||||||||||||||||||||||||||||||||
ANA | Parallels serum level | ||||||||||||||||||||||||||||||||||||||||
C3 | Parallels serum level | ||||||||||||||||||||||||||||||||||||||||
Glucose | Less than 10 mg/dL of blood level | ||||||||||||||||||||||||||||||||||||||||
Lactic acid | 5–20 mg/dL | ||||||||||||||||||||||||||||||||||||||||
pH | 7.2–7.4 | ||||||||||||||||||||||||||||||||||||||||
Protein | Less than 3 g/dL | ||||||||||||||||||||||||||||||||||||||||
RF | Parallels serum level | ||||||||||||||||||||||||||||||||||||||||
Uric acid | Parallels serum level | ||||||||||||||||||||||||||||||||||||||||
Crystals | None present | ||||||||||||||||||||||||||||||||||||||||
RBC count | None | ||||||||||||||||||||||||||||||||||||||||
WBC count | Less than 200 cells/microL | ||||||||||||||||||||||||||||||||||||||||
Neutrophils | Less than 25% | ||||||||||||||||||||||||||||||||||||||||
WBC morphology | No abnormal cells or inclusions | ||||||||||||||||||||||||||||||||||||||||
Gram stain and culture | No organisms present | ||||||||||||||||||||||||||||||||||||||||
AFB smear and culture | No AFB present | ||||||||||||||||||||||||||||||||||||||||
AFB = acid-fast bacilli; ANA = antinuclear antibodies; C3 = complement; RBC = red blood cell; RF = rheumatoid factor; WBC = white blood cell. |
Critical Findings and Potential Interventions
- Positive culture findings in any sterile body fluid.
Timely notification to the requesting health-care provider (HCP) of any critical findings and related symptoms is a role expectation of the professional nurse. A listing of these findings varies among facilities.
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