Synovial Fluid Analysis


Arthrocentesis, joint fluid analysis, knee fluid analysis.

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.

TestNormal Result
ColorColorless to pale yellow
ANAParallels serum level
C3Parallels serum level
GlucoseLess than 10 mg/dL of blood level
Lactic acid5–20 mg/dL
ProteinLess than 3 g/dL
RFParallels serum level
Uric acidParallels serum level
CrystalsNone present
RBC countNone
WBC countLess than 200 cells/microL
NeutrophilsLess than 25%
WBC morphologyNo abnormal cells or inclusions
Gram stain and cultureNo organisms present
AFB smear and cultureNo 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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