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URINALYSIS AND BODY FLUIDS (SEROUS FLUIDS)

Dr. Essam H. Jiffri

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SEROUS FLUIDS

- The closed cavities of the body mammal; the pleural, pericardial, and peritoneal cavities are each liner by two membranes referred to as the serous membranes.

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SEROUS FLUIDS

- One membrane lines the cavity wall (parietal membrane), and the other covers the organs within the cavity (visceral membrane).

- The fluid between the membranes which provides lubrication as the surfaces move against each other, is called serous fluid.

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SEROUS FLUIDS

- Normally only a small amount of serous fluid is present because production and absorption take place at a constant rate.

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Formation

- Serous fluids are formed as ultrafiltrates of plasma, with no additional material contributed by the membrane cells.

- Production and reabsorption are subject to hydrostatic and colloidal (oncotic) pressures from the capillaries serving the cavities under normal conditions.

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Formation

- The greater hydrostatic pressure in the systemic capillaries on the parietal side favors fluid production through the parietal membrane and reabsorption through the visceral membrane.

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Formation

- Fluids for laboratory examination are collected by needle aspiration from the respective cavities.

- These aspiration procedures are referred to as: thoracentesis (pleural) pericardiocentesis(pericardial). paracentesis (peritoneal).

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Formation

- Abundant fluid is usually collected; therefore, suitable specimens are available for each section of the laboratory.

- An anti-coagulated specimen is needed for cell counts, a sterile tube for culture.

- Large volumes of fluid should be prepared prior to microbiologic and cytologic examinations

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General Laboratory Procedures

- Routine fluid examination including classification as a transudate or exudate, appearance, cell count, differential, chemistry and microbiology procedures is performed in the same manner on all serous fluids.

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General Laboratory Procedures

- Cell counts are usually performed manually using the Neubauer counting chamber.

- Differential counts are performed on (Wright stained smears).

- Any suspicious cells been on the differential should be referrer to the cytology laboratory or the pathologist.

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Summary of Serous Fluid Testing

Pleural Fluid

Normal appearance: Clear, pale yellowTurbidity: White blood cells and microorganismsBlood: Traumatic injury, malignancy, traumatic tapMilky: Chylous or pseudochylous material Neutrophils: Bacterial infectionLymphocytes: Tuberculosis, malignancyNormal glucose: Parallels serum glucoseLow glucose: Tuberculosis, rheumatoid- inflammation, malignancyLow pH: Tuberculosis, malignancy, esophageal ruptureElevated amylase: Pancreatitis

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Summary of Serous Fluid Testing

Pericardial Fluid

Normal appearance: Clear, pale yellow

Milky: Lymphatic drainage

Turbidity: Infection, malignancy

Blood: Tuberculosis, tumor, cardiac puncture

Neutrophils: Bacterial endocarditis

Low glucose: Bacterial infection, malignancy

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Summary of Serous Fluid Testing

Peritoneal Fluid

Normal appearance: Clear, pale yellowTurbidity: Peritonitis, cirrhosisBlood: TraumaNeutrophils: PeritonitisLow glucose: Tubercular peritonitis, malignancyElevated amylase: Pancreatitis, gastrointestinal perforationElevated alkaline phosphatase: Intestinal perforationElevated urea or creatinine: Ruptured bladder

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TRANSUDATES AND EXUDATES

- Many pathologic conditions can cause a buildup (effusion) of serous fluid.

- A general classification of the cause of the effusion can be accomplished by separating the fluid into the category of transudate or exudate.

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TRANSUDATES AND EXUDATES

- Exudates are produced by conditions that directly involve the membranes of the particular cavity, including infections, malignancies and from an inflammatory process.

- Transudates also can be thought of as resulting from a mechanical process,

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TRANSUDATES AND EXUDATES

- A variety of laboratory tests have been used to differentiate between transudates and exudates, including appearance, specific gravity, total protein, lactic-dehydrogenase, cell counts, and spontaneous clotting.

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TRANSUDATES AND EXUDATES

- As can be seen using these criteria, one would expect a transudate to be a clear fluid with a specific gravity less than 1.015, protein less than 3.0 g per dl, and a lactic dehydrogenase below 200 IU.

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TRANSUDATES AND EXUDATES

- Traditionally, specific gravity and protein were considered to be the most valuable criteria for classification.

- In recent years, the lactic dehydrogenase has replaced the specific gravity.

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Laboratory Differentiation of Transudates and Exudate

___________________________________ Transudate Exudate

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Appearance Clear Cloudy

Specific gravity < 1.015 > 1.015

Total protein < 3.0 g/dl > 3.0 g/dl

Lactic dehydrogenase < 200 IU > 200 IU

Cell count < 1000/µl > 1000/µl

Spontaneous clotting No Possible

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