Chemical Examination

Pleural effusions are classified as transudates or exudates

with the former having protein content less than 3 g% and

the latter more than 3 g%.

Normal pleural fluid glucose is about equal to whole

blood glucose. Blood glucose changes are reflected in

pleural fluid after a lag period of 1 to 3 hours. A pleural

fluid glucose concentration 30–40 mg% less than whole

blood suggests bacterial infection (including tuberculosis), nonseptic inflammation (especially rheumatoid

pleuritis), or malignancy. In contrast to rheumatoid

disease, the effusions due to SLE typically have normal

glucose concentrations.

Microbiologic Examination

All effusions should be examined for bacteria by Gram’s

stain and culture. The possibility of tuberculosis should

always be considered with idiopathic pleural effusions.

PERICARDIAL FLUID (PF)

The pericardial sac under normal circumstances contains

20–50 mL of clear, straw-colored fluid. A rapid abnormal

accumulation of 200 mL may produce cardiac tamponade,

while gradual accumulation of 1000 mL or more may be

relatively asymptomatic (Table 12.6).

TABLE 12.6: Presence of pericardial fluid

Pericardial fluid Observation SI units

parameter

Apperance Clear to pale yellow

Glucose

Transudate Approximate whole

blood levels (Whole

blood adult norm

60–80 mg/dL,

Whole blood child

normal 51–85 mg/dL)

Exudate Lower than whole

blood levels

Lactate dehydrogenase

Transudate < Client’s serum LD

(serum adult normal

45–90 U/L,

serum child normal

60–170 U/L)

Indications for Pericardial Fluid Aspiration

1. Acute or chronic cardiac tamponade.

2. To confirm diagnosis and establish cause for pericardial

effusion of unknown etiology.

Complications of the (Blind) Pericardial Fluid

Aspiration

1. Cardiac arrhythmias, especially ventricular fibrillation.

2. Infection of pleural spaces by purulent pericardial

fluid.

3. Laceration of an atrium or coronary artery.

4. Pneumothorax.

5. Inadvertent injection of air into the cardiac chamber.

392 Concise Book of Medical Laboratory Technology: Methods and Interpretations Pericardial fluid aspiration: This should be in 3 sterile

tubes at least—EDTA tube for gross and microscopic

examination, plain or heparinized tube for microbiologic

examination, and heparinized tube for chemical

examination. Aspiration should be done under CT scan

guidance.

Gross Examination

Gross appearance of PF may be clear, cloudy, bloodtinged, grossly bloody, milky (chylous or pseudochylous)

or similar to gold paint.

Increased amounts of normal-appearing pericardial

fluid may be found in:

¾ Congestive heart failure

¾ Early stages of inflammation

¾ Some patients with idiopathic (viral) pericarditis.

Cloudy appearance may be associated with:

¾ Septic/nonseptic inflammation (bacterial, rheumatoid

or rheumatic)

¾ Chronic effusions of any etiology

¾ Myxedema

¾ Idiopathic

¾ Postmyocardial infarction syndrome.

Blood-tinged pericardial fluid is seen in:

¾ Traumatic tap, but it clears on aspirating more fluid.

Grossly bloody fluid may be caused by:

¾ Idiopathic hemorrhagic pericarditis (? viral)

¾ Postmyocardial infarction syndrome

¾ Postpericardiectomy syndrome

¾ Tuberculosis

¾ Rheumatoid arthritis

¾ Systemic lupus erythematosus

¾ Metastatic carcinoma

¾ Bacterial pericarditis

¾ Leaking aortic syndrome → (hemopericardium →

acute cardiac tamponade (hemopericardium has a

PCV similar to that of peripheral blood).

Milky pericardial fluid (unusual) may be due to:

¾ True chylopericardium

¾ Chronic pericarditis from any cause, e.g.

• Bacterial

• Fungal

• Tuberculous

• Rheumatoid pericarditis

• Rheumatic

• Myxedema.

Microscopic Examination

Total and differential counts done as for CSF. Increased

leukocytes with preponderance of neutrophils are

characteristic of bacterial pericarditis but may also be

seen in viral pericarditis or chronic postmyocardial infarction syndrome. A high percentage of lymphocytes suggest

tuberculous pericarditis.

Microbiologic Examination

Cultures for bacteria, fungi, and tuberculosis should be

performed in all effusions of unknown etiology.

Chemical Examination

Pericardial fluids should be classified as transudates or

exudates.

Transudates are typically seen in:

¾ Congestive heart failure

¾ Hypoproteinemic states

¾ Myxedema

¾ Viral pericarditis

¾ Early septic/nonseptic inflammation.

PERITONEAL FLUID

Normally, the peritoneal cavity contains less than 100 mL

of clear, straw-colored fluid (Table 12.7.

TABLE 12.7: Presence of peritoneal fluid

Peritoneal fluid Observation SI units parameter

Appearance Clear or pale yellow

Albumin Negative

Alkaline phosphatase

Adult female 76–250 U/L

Adult male 90–239 U/L

Ammonia < 50 g/L

Cholesterol

Transudate < 46 mg/dL < 1.19 mmol/L

Exudate > 46 mg/dL > 1.19 mmol/L

Glucose 60–100 mg/dL 3.3–6.1 mmol/L

Transudate Lower than whole

blood levels (Whole

blood adult normal

60–89 mg/dL, child

norm 51–85 mg/dL)

Lactic acid 10–20 mg/dL 1.1–2.3 mmol/L

Lactate

dehydrogenase

Transudate < Client’s serum LD

(serum adult normal

45–90 U/L, child

normal 60–170 U/L)

Exudate > Client’s serum LD

pH 7.4 7.4

Contd...

Cerebrospinal and Other Body Fluids 393

Peritoneal fluid Observation SI units parameter

Specific gravity

Transudate < 1.016 < 1.016

Exudate > 1.016 > 1.016

Total protein

Transudate < 2.5 g/dL < 25 g/L

Exudate > 3 g/dL > 30 g/L

Volume < 100 mL

White blood cells

Transudate < 100/mm3 < 100 × 109

/L

Exudate > 1000/mm3 > 1000 × 109

/L

Indications for Abdominal Paracentesis

To be done under ultrasound guidance.

1. Ascites of unknown etiology.

2. Symptomatic ascites, e.g. dyspnea.

3. Possible ruptured viscus or intra-abdominal hemorrhage due to trauma.

4. Acute abdominal pain of unknown etiology.

5. Postoperative hypotension and pain of unknown

etiology.

6. Instillation of cytotoxic drugs in ascites due to malignancy.

(The chief complication of abdominal paracentesis is

intestinal perforation, perforation of other viscera is rare.

If aspiration reveals gross blood or intestinal contents—

laparotomy must be done).

Gross Examination

Color of Peritoneal Fluid

Pale yellow to amber in:

¾ Congestive heart failure

¾ Hepatic vein obstruction

¾ Cirrhosis

¾ Nephrotic syndrome.

Similar appearance in:

¾ Ruptured urinary bladder.

Turbid fluid suggests peritonitis due to:

¾ Appendicitis

¾ Pancreatitis

¾ Strangulated/infarcted intestine

¾ Torn/ruptured bowel due to trauma/primary bacterial

infection.

Blood-tinged or grossly bloody fluid may be seen in:

¾ Ruptured spleen

¾ Ruptured liver

¾ Torn mesenteric vessels (trauma)

¾ Aortic aneurysm rupture

¾ Splenic artery, leaking aneurysm

¾ Hepatic vessel rupture

¾ Hemorrhagic pancreatitis

¾ Peritoneal laceration following muscular effort

¾ Traumatic tap—clears as more fluid is aspirated.

Greenish in:

¾ Perforated duodenal ulcer

¾ Perforated intestine

¾ Cholecystitis

¾ Perforated gallbladder

¾ Acute appendicitis (Biliary peritonitis is usually rapidly

fatal).

Milky fluid is due to chylous ascites, various causes are: