Serous Membranes and Cavities Flashcards
What are serous membranes and what do they line?
Serous membranes line the closed body cavities, including the pleural, pericardial, and peritoneal cavities.
What are the two layers of a serous membrane?
A serous membrane consists of a parietal membrane lining the cavity wall and a visceral membrane covering the organs within the cavity.
Where is serous fluid located?
Serous fluid is found between the parietal and visceral membranes.
What is the primary function of serous fluid?
The primary function of serous fluid is lubrication, which prevents friction between the membranes during organ movement.
How is serous fluid formed?
Serous fluids are formed as ultrafiltrates of plasma. The mesothelial cells lining the membranes do not contribute additional material.
What factors influence the production and reabsorption of serous fluid?
Production and reabsorption of serous fluid are influenced by hydrostatic pressure, colloidal (oncotic) pressure, and capillary permeability.
What is an effusion?
An effusion is defined as an increase in the amount of serous fluid between the membranes.
What are the primary causes of effusions?
Primary causes of effusions include increased hydrostatic pressure, decreased oncotic pressure, increased capillary permeability, and lymphatic obstruction.
How are fluids for laboratory examination collected?
Fluids for laboratory examination are collected by needle aspiration, such as thoracentesis, pericardiocentesis, and paracentesis.
What type of tubes are used for cell counts and differentials in serous fluid analysis?
EDTA tubes are used for cell counts and differentials.
What type of tubes are used for microbiology and cytology of serous fluids?
Sterile heparinized or SPS tubes are used for microbiology and cytology.
How should pH specimens of serous fluid be handled?
pH specimens must be kept anaerobic in ice.
Why are chemical tests on serous fluids often compared with plasma concentrations?
Chemical tests performed on serous fluids are often compared with plasma concentrations because the fluids are essentially plasma ultrafiltrates.
How are effusions generally classified?
Effusions are generally classified as transudates or exudates.
What causes transudates?
Transudates result from systemic disorders affecting fluid balance, such as heart failure or nephrotic syndrome.
What causes exudates?
Exudates arise from conditions directly involving the membranes, such as infections or malignancies.
What are traditional tests used to differentiate transudates and exudates?
Traditional tests include appearance, total protein, LDH, cell counts, and clotting.
What are the most reliable differentiators between transudates and exudates?
Fluid:blood ratios for protein and lactic dehydrogenase are the most reliable differentiators.
What does turbidity in serous fluid often indicate?
Turbidity often indicates infection or inflammation.
What can bloody fluid in serous cavities suggest?
Bloody fluid can suggest trauma or malignancy.
What does milky fluid in serous cavities suggest?
Milky fluid may indicate chylous or pseudochylous material.
What are the normal cellular components in pleural fluid?
Normal pleural fluid contains macrophages, lymphocytes, and a small number of neutrophils and mesothelial cells.
What does an increase in neutrophils in pleural fluid suggest?
Increased neutrophils suggest bacterial infection or pancreatitis.
What can elevated lymphocytes in pleural fluid indicate?
Elevated lymphocytes can indicate tuberculosis, viral infections, or autoimmune disorders.
What are mesothelial cells and where are they found?
Mesothelial cells line the serous cavities and can be found in serous fluids.
What is a primary concern when analyzing serous fluid for cytology?
Detecting malignant cells is a primary concern.
What are common chemical tests for pleural fluid?
Common chemical tests include glucose, pH, ADA, and amylase.
What can decreased glucose in pleural fluid indicate?
Decreased glucose can be seen in tuberculosis, rheumatoid inflammation, malignancy, and infections.
What does low pH in pleural fluid suggest?
Low pH may indicate the need for chest-tube drainage.
What is elevated ADA in pleural fluid indicative of?
Elevated ADA is indicative of tuberculosis.
What microbiological and serological tests are performed for suspected infections in serous fluids?
Gram stains, cultures, and acid-fast stains are performed for suspected infections. Serological tests like ANA and rheumatoid factor can help differentiate immunologic origins.
What are tumor markers used for in serous fluid analysis?
Tumor markers (CEA, CA 125) are used for effusions of malignant origin.
What are pericardial effusions classified as and what do laboratory tests focus on?
Pericardial effusions can be transudates or exudates. Laboratory tests focus on differentiating transudates and exudates.
What is ascites?
Ascites is peritoneal effusion.
How is the differentiation between transudates and exudates often done for ascitic fluid?
The serum-ascites albumin gradient (SAAG) is often used.
What does a SAAG of ≥ 1.1 g/dL suggest?
A SAAG of 1.1 g/dL or greater strongly suggests a transudate of hepatic origin, commonly seen in cirrhosis.
What is peritoneal lavage used for?
Peritoneal lavage may be performed to detect intra-abdominal bleeding in trauma cases.
What does a turbid peritoneal fluid typically indicate?
Turbid peritoneal fluid typically indicates bacterial or fungal infections (peritonitis).
What can a green or dark-brown peritoneal fluid color suggest?
A green or dark-brown color suggests bile leakage, often from gallbladder or pancreatic issues.
What can decreased ascitic fluid glucose indicate?
Ascitic fluid glucose is decreased in bacterial peritonitis, tuberculosis, and malignancy.
What can elevated amylase levels in ascitic fluid indicate?
Elevated amylase levels can indicate pancreatitis or gastrointestinal perforation.
What does alkaline phosphatase elevation in ascitic fluid suggest?
Alkaline phosphatase elevation suggests intestinal perforation.