Type of test Fluid analysis

 Normal findings

 Gross appearance: Clear, serous, light yellow, 50 mL

Red blood cells (RBCs): None

White blood cells (WBCs): < 300/mL

Protein: < 4.1 g/dL

Glucose: 70-100 mg/dL

Amylase: 138-404 units/L

Alkaline phosphatase

 Adult male: 90-240 units/L

Female: < 45 years: 76-196 units/L

Female: > 45 years: 87-250 units/L

Lactic dehydrogenase (LDH): Similar to serum LDH

Cytology: No malignant cells

Bacteria: None

 Fungi: None

Carcinoembryonic antigen (CEA): < 5 ng/mL

 Test explanation and related physiology

Thoracentesis is an invasive procedure that entails insertion of a needle into the pleural space for removal of fluid (Figure 1). Pleural fluid is removed for diagnostic and therapeutic purposes. Therapeutically, it is done to relieve pain, dyspnea, and other symptoms of pleural pressure. Removal of this fluid also permits better radiographic visualization of the lung. Diagnostically, thoracentesis is performed to obtain and analyze fluid to determine the etiology of the pleural effusion.

Fig1. Thoracentesis. A needle is placed through the chest wall and into the fluid contained in the pleural cavity. A special one way valve system is placed between the needle and the syringe to allow aspiration of fluid when the plunger of the syringe is pulled back and diversion of the fluid to a container when the plunger is pushed in.

Pleural fluid is classified according to transudate or exudate. Transudates are most frequently caused by congestive heart failure, cirrhosis, nephrotic syndrome, and hypoproteinemia. Exudates are most often found in inflammatory, infectious, or neoplastic conditions. However, collagen vascular disease, pulmonary infarction, trauma, and drug hypersensitivity also may cause an exudative effusion.

Pleural fluid is usually evaluated for the following features.

Gross appearance

 The color, optical density, and viscosity are noted as the pleural fluid appears in the aspirating syringe. Empyema is characterized by the presence of a foul odor and thick, puslike fluid. An opalescent, pearly fluid is characteristic of chylothorax.

Cell counts

The WBC and differential counts are determined. A WBC count exceeding 1000/mL is suggestive of an exudate. The pre dominance of polymorphonuclear leukocytes usually is an indication of an acute inflammatory condition (e.g., pneumonia). When more than 50% of the WBCs are small lymphocytes, the effusion is usually caused by TB, or tumor. The presence of RBCs may indicate neoplasms, TB, or intrathoracic bleeding.

Protein content

Whereas total protein levels greater than 3 g/dL are characteristic of exudates, transudates usually have a protein content of less than 3 g/dL. The albumin gradient between serum and pleural fluid can differentiate better between the transudate and exudate natures of pleural fluid than can the total protein content. This gradient is obtained by subtracting the pleural albumin value from the serum albumin value. Values of 1.1 g/dL or more suggest a transudate. Values less than 1.1 g/dL suggest an exudate but will not differentiate the potential cause of the exudate (e.g., malignancy from infection or inflammation). The total protein ratio (fluid/serum) has been considered to be another accurate criterion differentiating transudate from exudate. A total protein ratio of fluid to serum of greater than 0.5 is considered to be an exudate.

Lactic dehydrogenase

 A pleural fluid/serum LDH ratio greater than 0.6 is typical of an exudate. An exudate is identified with a high degree of accuracy if the pleural fluid/serum protein ratio is greater than 0.5 and the pleural fluid/serum LDH ratio is greater than 0.6.

Glucose

Usually pleural glucose levels approximate serum levels. Low values appear to be a combination of glycolysis by the extra cells and impairment of glucose diffusion because of damage to the pleural membrane. Values less than 60 mg/dL are occasionally seen in TB, or malignancy and typically occur in rheumatoid arthritis and empyema.

Amylase

 In a malignant effusion, the amylase concentration is slightly elevated. Amylase levels above the normal range are seen when the effusion is caused by pancreatitis or rupture of the esophagus associated with leakage of salivary amylase.

Triglyceride

Measurement of triglyceride levels is an important part of identifying chylous effusions. These effusions are usually produced by obstruction or transection of the lymphatic system caused by lymphoma, neoplasm, trauma, or recent surgery.

Gram stain and bacteriologic culture

These tests are routinely performed when bacterial pneumonia or empyema is a possible cause of the effusion.

Cultures for Mycobacterium tuberculosis and fungus

Tuberculosis is less often a cause for pleural effusion in the United States today than it was. Fungus may be a cause of pulmonary effusion in patients with compromised immunologic defenses.

Cytology

 A cytologic study is performed to detect tumor cells in patients with malignant effusions. Breast and lung are the two most common tumors; lymphoma is the third.

Carcinoembryonic antigen

 Pleural fluid CEA levels are elevated in various malignant (gastrointestinal, breast) conditions (p. 196).

Special tests

The pH of pleural fluid is usually 7.4 or greater. The pH is typically less than 7.2 when empyema is present. The pH may be 7.2 to 7.4 in TB, or malignancy.

In some instances, the rheumatoid factor (p. 785) and the complement levels (p. 267) are also measured in pleural fluid.

Pleural fluid antinuclear antibody (ANA) levels and pleural fluid/serum ANA ratios are often used to evaluate pleural effusion secondary to systemic lupus erythematosus. When tuberculosis (TB) is suspected, the effusion can be tested for Adenosine Deaminase (ADA). ADA is an enzyme in lymphocytes and myeloid cells. ADA levels are elevated in inflammatory effusions caused by bacterial infections, granulomatous inflammation (e.g., tuberculosis, sarcoidosis), malignancy, and autoimmune diseases (e.g., lupus, vasculitis). ADA is normally elevated in all neutrophil- predominant effusions (such as bacterial infections) but among lymphocyte-predominant effusions, levels of ADA are typically higher in those caused by TB. ADA cannot distinguish between latent and active TB.

Contraindications

 • Patients with significant thrombocytopenia

 Potential complications

• Pneumothorax because of puncture of the visceral pleura or entry of air into the pleural space

 • Interpleural bleeding because of puncture of tissue or a blood vessel

 • Hemoptysis caused by needle puncture of a pulmonary vessel or by inflammation

• Reflex bradycardia and hypotension

• Pulmonary edema

• Seeding of the needle track with tumor when malignant pleural effusion exists

 Procedure and patient care

 Before

* Explain the procedure to the patient.

 • Obtain informed consent for this procedure.

* Tell the patient that no fasting or sedation is necessary. Inform the patient that movement or coughing should be minimized to avoid inadvertent needle damage.

 • Administer a cough suppressant before the procedure if the patient has a troublesome cough.

During

 • Note the following procedural steps:

 1. The patient is usually placed in an upright position, with the arms and shoulders raised and supported on a padded overhead table.

 2. The thoracentesis is performed under strict sterile technique.

3. The needle insertion site, which is determined by percussion, auscultation, and examination of a chest x-ray image, ultrasound scan, or fluoroscopy, is aseptically cleansed and anesthetized locally.

4. The needle is positioned in the pleural space, and the fluid is withdrawn with a syringe and a three-way stopcock.

5. A short polyethylene catheter may be inserted into the pleural space for fluid aspiration.

 • Monitor the patient’s pulse for reflex bradycardia and evaluate the patient for diaphoresis and a feeling of faintness.

• Note that this procedure is performed by a physician at the patient’s bedside, in a procedure room, or in the physician’s office in less than 30 minutes.

* Although local anesthetics eliminate pain at the insertion site, tell the patient that he or she may feel a pressure-like pain when the pleura is entered and the fluid is removed.

 After

 • Place a small bandage over the needle site. Usually turn the patient on the unaffected side for 1 hour to allow the pleural puncture site to heal.

• Send the labeled specimen promptly to the laboratory.

 • Obtain a chest x-ray to check for pneumothorax.

• Monitor the patient’s vital signs.

• Observe the patient for coughing or expectoration of blood (hemoptysis), which may indicate trauma to the lung.

• Evaluate the patient for signs and symptoms of pneumothorax, tension pneumothorax, subcutaneous emphysema, and pyogenic infection (e.g., tachypnea, dyspnea, diminished breath sounds, anxiety, restlessness, fever).

Abnormal findings

  Exudate

- Empyema

- Pneumonia

- TB, effusion

- Pancreatitis

- Ruptured esophagus

- Tumors

- Lymphoma

- Pulmonary infarction

- Collagen vascular disease

- Drug hypersensitivity

Transudate

- Cirrhosis

- Congestive heart failure

- Nephrotic syndrome

- Hypoproteinemia

- Trauma

اخر الاخبار

اخبار العتبة العباسية المقدسة

العتبة العباسية المقدسة: نهج البلاغة مصدر صافٍ للفكر والمعرفة ومحصِّنٌ من الشبهات

العتبة العباسية المقدسة تطلق محاضرات محفل نهج البلاغة الأسبوعي في ذي قار

العتبتان المقدستان الحسينية والعباسية تدعوان للمشاركة في مهرجان الشموع بنسخته السادسة والعشرين

بالتعاون مع مستشفى الكفيل.. قسم الشؤون الطبّية يواصل إقامة البرنامج التدريبي لملاكاته النسوية

المزيد

الآخبار الصحية

الصحة العالمية تكشف حقيقة انتشار فيروس نيباه خارج الهند

متى يصبح محيط الخصر "مؤشر خطر"؟

دراسة تكشف دور "العوامل الوراثية" في تحديد عمر الإنسان

رائحة كريهة في الجسم.. "علامة خفية" أخطر مما تتصور

المزيد

الآخبار التكنلوجية

مايكروسوفت تكشف عن الجيل الثاني من شرائحها للذكاء الاصطناعي

خرافة "ثمانية أكواب يوميا".. كم من الماء يحتاج جسمك فعليا؟

هل توجد حياة خارج كوكبنا؟.. اكتشاف جديد يثير اهتمام العلماء

اكتشاف الخلايا المسؤولة عن فقدان ذاكرة الطفولة

المزيد

مواضيع ذات صلة

thyroid scanning (Thyroid scintiscan)

thyroid fine needle aspiration biopsy (FNAB, Skinny needle thyroid biopsy, Fine-needle aspiration [FNA])

The Role of Laboratory in Urgency: Altered State of Consciousness

Preoperative Laboratory Test

sputum culture and sensitivity (C&S, Culture and Gram stain)

sodium (Na), blood

small intestinal bacterial overgrowth test (SIBO test, Lactulose Breath Test)

Clinical Biochemistry of Exercise: The Benefits of Movement

Medium- to Long-term Effects of Physical Activity on Laboratory Parameters

Acute Effects of Sports Performance on Laboratory Parameters

ProstaScint scan (Radioimmunoscintigraphy of the prostate [RIS])

pregnanediol