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Cytology exam of pleural fluid

Pleural fluid cytology; Lung cancer - pleural fluid

A cytology exam of pleural fluid is a laboratory test to detect cancer cells and certain other cells in the fluid from the area that surrounds the lungs. This area is called the pleural space. Cytology means the study of cells.

How the Test is Performed

A sample of fluid from the pleural space is needed. The sample is taken using a procedure called thoracentesis.

The procedure is done in the following way:

The fluid sample is sent to a laboratory. There, it is examined under the microscope to determine what the cells look like and whether they are abnormal.

How to Prepare for the Test

No special preparation is needed before the test. A chest x-ray or ultrasound will likely be done before and after the test.

Do not cough, breathe deeply, or move during the test to avoid injury to the lung.

How the Test will Feel

You will feel stinging when the local anesthetic is injected. You may feel pain or pressure when the needle is inserted into the pleural space.

Tell your health care provider if you feel short of breath or have chest pain.

Why the Test is Performed

A cytology exam is used to look for cancer and precancerous cells. It may also be done for other conditions, such as identifying systemic lupus erythematosus cells. Occasionally, microorganisms can be seen in cytology too, but in general, they are best identified by culture.

Your doctor may order this test if you have signs of fluid buildup in the pleural space. This condition is called pleural effusion. The test may also be done if you have signs of lung cancer.

Normal Results

Normal cells are seen.

What Abnormal Results Mean

In an abnormal result, there are cancerous (malignant) cells. This may mean there is a cancerous tumor. This test most often detects:

Risks

Risks are related to thoracentesis and may include:

Related Information

Pleural effusion
Tumor
Breast cancer
Lung cancer - small cell
Hodgkin lymphoma
Lung metastases

References

Blok BK. Thoracentesis. In: Roberts JR, Custalow CB, Thomsen TW, eds. Roberts and Hedges' Clinical Procedures in Emergency Medicine and Acute Care. 7th ed. Philadelphia, PA: Elsevier; 2019:chap 9.

Cibas ES. Pleural, pericardial, and peritoneal fluids. In: Cibas ES, Ducatman BS, eds. Cytology. 5th ed. Philadelphia, PA: Elsevier; 2021:chap 4.

Chernecky CC, Berger BJ. Thoracentesis - diagnostic. In: Chernecky CC, Berger BJ, eds. Laboratory Tests and Diagnostic Procedures. 6th ed. St Louis, MO: Elsevier Saunders; 2013:1052-1135.

Ruhl TS, Good JL. Thoracentesis. In: Fowler GC, Choby BA, Iyengar D, et al, eds. Pfenninger and Fowler's Procedures for Primary Care. 4th ed. Philadelphia, PA: Elsevier; 2020:chap 218.

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Review Date: 7/31/2022  

Reviewed By: Denis Hadjiliadis, MD, MHS, Paul F. Harron Jr. Professor of Medicine, Pulmonary, Allergy, and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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