| Subject | Contents |
| Definition | The pleural fluid gram stain is a method of staining microorganisms using a violet stain. In this test, a small amount of pleural fluid (fluid found in the space surrounding the lungs) is examined under the microscope. The gram stain method can be applied to almost any clinical specimen, and it is one of the best techniques for the rapid diagnosis of bacterial infections. |
| Alternative Names | Gram stain of pleural fluid |
| How the test is performed | A sample of pleural fluid obtained by thoracentesis (needle aspiration ) is applied in a very thin layer to a microscope slide. The specimen is stained with a violet stain, known as a gram stain, and then examined under the microscope for the presence of bacteria. The color, number, and morphologic appearance of the cells help make it possible to identify the organism. |
| How to prepare for the test | Adults: It is important not to cough , breathe deeply, or move when the fluid sample is being taken. There is no other special preparation for the test. Infants and children: The physical and psychological preparation you can provide for this or any test or procedure depends on your child's age, interests, previous experiences, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child's age:Infant test or procedure preparation (birth to 1 year) Toddler test or procedure preparation (1 to 3 years) Preschooler test or procedure preparation (3 to 6 years) Schoolage test or procedure preparation (6 to 12 years) Adolescent test or procedure preparation (12 to 18 years) |
| How the test will feel | The specimen is obtained by thoracentesis (a needle aspiration of fluid in the pleural space). The chest is cleansed with antibacterial soap. The area is anesthetized with local anesthetic. Then, a needle is placed between the ribs, and a sample of fluid is withdrawn from the chest. You may feel a stinging sensation when the anesthetic in injected. You may feel some pressure and slight localized pain when the thoracentesis needle enters the pleural space. A chest X-ray is usually done following the test to be sure the lung tissue was not affected by the test. |
| Why the test is performed | The test is performed when infection of the pleural space is suspected or when an abnormal collection of pleural fluid is noticed by chest X-ray . |
| Normal Values | Normally, no organisms are present in the pleural fluid. |
| What abnormal results mean | A bacterial infection of the pleura (lining of the lungs) may be present. |
| What the risks are | There is a risk of internal bleeding into the lung and pneumothorax ( collapsed lung ). Serious complications are extremely rare. |
| Special considerations | The fluid smear cost does not include the cost of the procedure to obtain the specimen. Other tests may be done on the sample of fluid obtained. |
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