Serous Fluid Analysis and Classification

Collected via needle aspiration from body cavities like the pleural, pericardial, and peritoneal cavities.

Collection of serous fluid from the pleural cavity.

Collected in plain tubes or tubes with heparin, depending on the chemistry test needed.

Maintained anaerobically, on ice, to preserve for pH testing.

Chemical tests are compared to plasma chemical concentrations.

Serous fluid lubricates the parietal and visceral membranes, preventing friction during organ movement.

Serous fluid is an ultrafiltrate of plasma, with no additional material from mesothelial cells.

Fluid buildup due to systemic issues affecting fluid balance.

Fluid buildup directly involving the membranes due to infection or malignancy.

Clear liquid.

Cloudy liquid.

0.5 or less

Disruption of serous fluid balance, leading to abnormal fluid buildup.

Exudate is a fluid with high protein content, indicating inflammation or infection. Transudate is a fluid with low protein content, usually caused by pressure imbalances.

The ratio of lactate dehydrogenase (LD) in a fluid sample to that in serum. A ratio greater than 0.6 suggests an exudate.

The cholesterol level in pleural fluid. A level >45 mg/dL suggests an exudate.

The ratio of cholesterol in pleural fluid to that in serum. A ratio >0.3 suggests an exudate.

The ratio of bilirubin in pleural fluid to that in serum. A ratio >0.6 suggests an exudate.

The ratio of cholesterol in ascitic fluid to that in serum. A ratio >1.1 suggests an exudate.

High lymphocyte counts in pleural fluid suggest tuberculosis, viral infections, malignancy, or autoimmune disorders like rheumatoid arthritis or lupus.

High eosinophil counts (>10%) in pleural fluid can indicate trauma like pneumothorax or hemothorax (air or blood in the pleural cavity).

High levels of amylase in body fluids, like pleural fluid, are often associated with pancreatitis.

Common bacteria causing pleural effusions include Staphylococcus aureus, Enterobacteriaceae, Anaerobes, and Mycobacterium tuberculosis.

Tests like ANA and RF help differentiate immunologic effusions from non-inflammatory processes.

Markers like CEA, CA 125, CA 15.3, CA 549, and CYFRA 21-1 can help diagnose effusions of malignant origin.

Fluid found in the peritoneal cavity, commonly called ascitic fluid.

Common causes of transudate ascites include hepatic disorders like cirrhosis.

Bacterial infection of the peritoneum, often due to intestinal perforation or a ruptured appendix.

Analysing peritoneal fluid helps determine the cause of ascites, such as infection or malignancy.

Infection is suspected when the absolute neutrophil count is 250 cells/uL or greater, or when neutrophils make up 50% or more of total white blood cells.

Lymphocytes are the dominant type of white blood cell in tuberculosis infections.

Examining ascitic fluid for cancer cells helps identify primary or metastatic tumors, often originating in the gastrointestinal tract, prostate, or ovaries.

Low glucose levels in ascitic fluid compared to serum can indicate bacterial or tubercular infections, as well as malignancy.

Elevated amylase in ascitic fluid suggests pancreatitis or gastrointestinal perforations.

High alkaline phosphatase in ascitic fluid is a strong indicator of intestinal perforation.

The placenta supplies the water and dissolved substances in amniotic fluid.

A high white blood cell count (over 1000 WBCs/uL) with a significant percentage of neutrophils suggests bacterial endocarditis.

Amniotic fluid contains various substances like glucose, protein, and creatinine, reflecting the fetal metabolic processes.

Creatinine levels in amniotic fluid rise as the fetus matures, helping determine gestational age.

Amniotic fluid contains significantly lower concentrations of creatinine and urea compared to urine.

A test to detect amniotic fluid using a microscopic examination of a vaginal fluid sample that reveals fern-like crystals.

A serious infection of the abdominal lining, often diagnosed through testing of abdominal fluid.

Amniotic fluid analysis, particularly creatinine levels, is used to estimate fetal age.

Tests performed in the absence of oxygen, often for bacterial peritonitis, to identify anaerobic bacteria.