Joint fluid Gram stain

定义

Joint fluid Gram stain is a laboratory test to identify bacteria in a sample of joint fluid using a special series of stains (colors). 的 Gram stain method is one of the most commonly used methods to rapidly identify the cause of bacterial infections.

Alternative Names

Gram stain of joint fluid

How the Test is Performed

A sample of joint fluid is needed. This may be done in a health care provider's office using a needle, or during an operating room procedure. Removing the sample is called joint fluid aspiration.

的 fluid sample is sent to a lab where a drop of fluid is spread in a very thin layer onto a microscope slide. This is called a smear. Several different colored stains are applied to the sample. 的 laboratory personnel will look at the stained smear under a microscope to see if bacteria are present. 的 color, size, and shape of the cells help identify the bacteria.

How to Prepare for the Test

Your provider will tell you how to prepare for the procedure. No special preparation is needed. 但, tell your provider if you're taking a blood thinner, 比如阿司匹林, warfarin (Coumadin) or clopidogrel (Plavix). 的se medicines can affect test results or your ability to take the test.

How the Test will Feel

有时, the provider will first inject numbing medicine into the skin with a small needle, 可能会有刺痛. A larger needle is then used to draw out the synovial fluid.

This test may also cause some discomfort if the tip of the needle touches bone. 的 procedure usually lasts less than 1 to 2 minutes.

Why the Test is Performed

的 test is performed when there is unexplained swelling, 关节疼痛, and inflammation of a joint, or to check for suspected joint infection.

正常的结果

A normal result means no bacteria are present on the Gram stain.

What Abnormal Results Mean

Abnormal results mean bacteria were seen on the Gram stain. This may be a sign of a joint infection, for example, gonococcal arthritis due to bacteria called Neisseria gonorrhoeae or arthritis due to bacteria called Staphylococcus aureus.

风险

风险 of this test include:

• Infection of the joint -- unusual, but more common with repeated aspirations
• Bleeding into the joint space

参考文献

El-Gabalawy HS, Tanner S. Synovial fluid analyses, synovial biopsy, and synovial pathology. In: Firestein GS, Budd RC, Gabriel SE, Koretzky GA, McInnes IB, O'Dell JR, eds. Firestein & Kelly's Textbook of Rheumatology. 11日艾德. Philadelphia, PA: Elsevier; 2021:chap 56.

Karcher DS, McPherson RA. Cerebrospinal, synovial, serous body fluids, and alternative specimens. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24日艾德. Philadelphia, PA: Elsevier; 2022:chap 30.