Serous Fluid (Textbook)

Question 1

Serous Fluid Formation

Answer 1

Like synovial fluids, serous fluids are formed as ultrafiltrates of plasma; no additional material is contributed by the mesothelial cells that line the membranes.

Question 2

Hydrostatic and Oncotic Pressures

Answer 2

Production and reabsorption of ultrafiltrate are subject to hydrostatic pressure and colloidal pressure (oncotic pressure) from the capillaries that serve the cavities and the capillary permeability.

Oncotic pressure from serum proteins is the same in the capillaries on both sides of the membrane, so hydrostatic pressure in the parietal and visceral capillaries causes fluid to enter between the membranes. Filtration of the plasma causes increased oncotic pressure in the capillaries that allows reabsorption of fluid back into the capillaries.

Question 3

Effusion in Serous Fluids

Answer 3

Disruption of the mechanisms of serous fluid formation and reabsorption causes an increase in fluid between the membranes.

Primary causes: increased hydrostatic pressure (congestive heart failure), decreased oncotic pressure (hypoproteinemia), increased capillary permeability (inflammation and infection), and lymphatic obstruction (tumors)

Question 4

Three kinds of Aspiration Procedures

Answer 4

• Thoracentesis (pleural)
• Pericardiocentesis (pericardial)
• Paracentesis (peritoneal)

Question 5

Serous Fluid Anticoagulants

Answer 5

• EDTA: cell counts/differential
• Heparinized or sodium polyanethol sulfonate (SPS): microbiology and cytology.

Question 6

Transudates in Serous Fluid

Answer 6

Form because of a systemic disorder that disrupts the balance in the regulation of fluid filtration and reabsorption

• Congestive heart failure: changes in hydrostatic pressure
• Nephrotic syndrome: hypoproteinemia

Usually it is unnecessary to test transudate fluids.

Question 7

Exudates in Serous Fluid

Answer 7

Produced by conditions that directly involve the membranes of the particular cavity:

• Infections
• Malignancies

Question 8

Differentiating Transudates from Exudates

Answer 8

Most reliable differentiation is usually obtained by determining the fluid:blood ratios for protein and lactic dehydrogenase.

Question 9

Exudative Testing

Answer 9

Examined for microbiologic and cytologic
abnormalities

RBC/WBC counts are not routinely performed, however differentials are because cell type ratios can give and idea of what is causing the exudate:

• Neutrophils are increased in effusions resulting from pancreatitis and pulmonary infarction
• Elevated lymphocyte counts are seen in tuberculosis, viral infections, malignancy, and autoimmune disorders (RA and SLE)

Question 10

Differentiating Pleural Effusions

Answer 10

Either transudative or exudative, differentiated by pleural fluid cholesterol level, pleural fluid:serum cholesterol ratio and the pleural fluid:serum total bilirubin ratio.

A pleural fluid cholesterol >60 mg/dL, a pleural fluid:serum cholesterol ratio >0.3, or a fluid:serum total bilirubin ratio of >0.6 provides reliable information that the fluid is an exudate.

Question 11

Determining Source of Blood in Pleural Samples

Answer 11

If the fluid hematocrit is more than 50% of the whole blood hematocrit, the effusion comes from a (hemothorax) injury.
A lower hematocrit indicates a chronic membrane
disease because the effusion contains both blood and increased pleural fluid

Question 12

Cholesterol Testing in Pleural Fluids

Answer 12

• Chylous material: Thoracic Duct leakage, high concentration of triglycerides
• Pseudochylous material: Chonic Inflammatory conditions, higher concentration of cholesterol.

Question 13

Pleural Fluid Differential

Answer 13

In addition to Neutrophil and Lymphocyte counts,

Mesothelial cells: noticeable lack of associated with tuberculosis, from exudate covering the pleural membranes, and an increase in the presence of pleural fluid plasma cells.

Question 14

Pleural Fluid Chemical Tests

Answer 14

Glucose: Decreased glucose in tuberculosis, rheumatoid inflammation, and purulent infections (Lactate will also be elevated).

pH: 0.30 degrees lower than the blood pH is considered significant, value as low as 6.0 indicates an esophageal rupture that is allowing the influx of
gastric fluid.

Adenosine deaminase (ADA): Levels higher than 40 U/L indicate tuberculosis or malignancy.

Amylase: Elevated levels associated with pancreatitis, often elevated first in the pleural fluid.

Triglyceride levels may be included to confirm a chylous effusion.

Question 15

Pleural Fluid Serelogical Tests

Answer 15

Differentiates effusions of immunologic origin from noninflammatory processes:

• Antinuclear antibody (ANA)
• Rheumatoid factor (RF)

Or tumor markers:

• Carcinoembryonic antigen (CEA)
• CA 125 (metastatic uterine cancer)
• CA 15.3
• CA 549 (breast cancer)
• CYFRA 21-1 (lung cancer)

Question 16

Pericardial Effusions

Answer 16

Exudates: Primarily the result of changes in the membrane permeability due to infection (pericarditis), malignancy, and trauma

Transudates: Metabolic disorders such as uremia, hypothyroidism, and autoimmune disorders

Question 17

Tamponade

Answer 17

An effusion is suspected when cardiac compression occurs, caused by fluid surrounding the heart.

Question 18

Pericardial Effusion Appearance

Answer 18

• Malignant effusions are frequently blood streaked.
• Grossly bloody effusions are associated with accidental cardiac puncture and misuse of anticoagulant medications.
• Milky fluids representing chylous and pseudochylous effusions may also be present.

Question 19

Differentiating Pericardial Fluid Effusions

Answer 19

The fluid:serum protein and lactic dehydrogenase (LD) ratios.

A count of >1000 WBCs/µL with a high percentage of neutrophils can indicate bacterial endocarditis.

During differentials, the malignant cells most frequently encountered are the result of metastatic lung or breast carcinoma a

Question 20

Pericardial Fluid Special Testing

Answer 20

Fluid tumor marker levels correlate well with cytologic studies.

Acid-fast staining/adenosine deaminase due to tubercular effusions are increasing as a result of AIDS.

Question 21

Peritoneal Fluid

Answer 21

Fluid between the peritoneal membranes is called ascites, or ascites fluid

Question 22

Peritoneal Transudates and Exudates

Answer 22

Transudates: hepatic disorders (cirrhosis)

Exudates: Bacterial infections (peritonitis) (a result of intestinal perforation/ruptured appendix) and malignancy

Question 23

Peritoneal Lavage

Answer 23

Sensitive test to detect intra-abdominal bleeding in blunt trauma cases, and results of the RBC count can be used along with radiographic procedures to aid in determining the need for surgery.

Question 24

Peritoneal Cell Counts/Differentials

Answer 24

Requested on fluid from peritoneal dialysis to detect infection, and eosinophil counts to detect allergic reactions to the equipment or introduction of air into the peritoneal cavity.

An absolute neutrophil count >250 cells/µL
or >50% of the total WBC count indicates infection.

Lymphocytes are the predominant cell in tuberculosis.

Question 25

Serum-ascites Albumin Gradient (SAAG)

Answer 25

Recommended over the fluid:serum total protein and LD ratios to detect transudates of hepatic origin.

Fluid and serum albumin levels are measured concurrently, and the fluid albumin level is subtracted from the serum albumin level.

A difference (gradient) of >1.1 is a transudate effusion of hepatic origin, and lower gradients are associated with exudative effusions

Question 26

Peritoneal Fluid Appearance

Answer 26

• Green or dark-brown: presence of bile, which can be confirmed using standard chemical tests for bilirubin.
• Blood-streaked: after trauma, and with tuberculosis, intestinal disorders, and malignancy.
• Chylous or pseudochylous: material may be present with trauma or lymphatic vessels blockage.

Question 27

Peritoneal Fluid Malignancy Cellular Findings

Answer 27

Most frequently of gastrointestinal, prostate, or ovarian origin, and include cells with mucin-filled vacuoles

Psammoma bodies: containing concentric striations of collagen-like material, seen in benign conditions and ovarian/thyroid malignancies

Normal cells present in ascitic fluid include leukocytes, abundant mesothelial cells, and macrophages, including lipophages

Question 28

Peritoneal Fluid Chemical Tests

Answer 28

Primarily of glucose, amylase, and alkaline phosphatase determinations.

If a ruptured bladder or accidental puncture during paracentesis is of concern, blood urea nitrogen and creatinine are requested.

When leakage of bile into the peritoneum is suspected following trauma or surgery, bilirubin is measured - bile has mostly conjugated bilirubin; so total bilirubin is used.

Pancreatitis or damage to the pancreas is suspected, amylase or lipase can be measured

Question 29

Peritoneal Fluid Serology

Answer 29

Tumor markers:

• CEA
• CA 125

Positive CA 125 antigen with a negative CEA suggests the source is from the ovaries, fallopian tubes, or endometrium.