Analysis of Body Fluids
Dr. Gangadhar Chatterjee
Dept. of Biochemistry
Fluid accumulation in the pleural, pericardial, and
peritoneal cavities is known as a serous effusion.
potential space lined by mesothelium of the
visceral and parietal pleurae.
The fluid is plasma filtrate derived from capillaries
of the parietal pleura.
Produced continuously at a rate dependent on
capillary hydrostatic pressure, plasma oncotic
pressure, and capillary permeability.
Except for an EDTA tube for total and
differential cell counts, the specimen
should be collected in heparinized tubes to
If malignancy, fungal or mycobacterial
infection suspected, all remaining fluid
(≥100 mL) should be submitted to
maximize the yield of stains and culture.
Pleural fluid is exudate if one or more:
Pleural LDH/Serum LDH > 0.6* -ORPleural protein/Serum protein > 0.5 -ORPleural LDH > 2/3 upper limit of normal
Usually > 200 IU
Absence of ALL: transudate
Sensitivity 99%, Specificity 98%
-Transudates typically clear, pale yellow to
straw-colored, and odorless and do not clot
- traumatic tap suggested by uneven blood
distribution, fluid clearing with continued
aspiration, or formation of small blood
-True chylous effusions produced by
leakage from the thoracic duct resulting from
obstruction by lymphoma, carcinoma, or
Pseudochylous or chyliform effusions may
accumulate gradually through the
breakdown of cellular lipids in long
standing effusions such as rheumatoid
pleuritis, tuberculosis, or myxedema.
-Differential Leukocyte Count and Cytology
pleural fluid total protein or albumin has little
Decreased pleural fluid glucose ie. level
below 60 mg/dL or a pleural fluid/serum
glucose ratio less than 0.5, most consistent
and dramatic in rheumatoid pleuritis and
grossly purulent parapneumonic exudates
useful adjunct in the rapid diagnosis of
elevations above the serum level (usually
1.5–2.0 or more times greater) indicate the
presence of pancreatitis, esophageal
rupture, or malignant effusion
Pleural fluid LD levels rise in proportion to
the degree of inflammation.
Significantly increased in tuberculous
ADA levels of 40 U/L or greater are present
in about 99.6% of patients with verified
significantly increased in then pleural fluid
of patients with tuberculous pleuritis. The
sensitivity of levels of 3.7 IU/L or greater is
99%, and the specificity is 98%.
highest diagnostic accuracy in assessing the
prognosis of parapneumonic (pneumoniarelated) effusions.
parapneumonic exudate with a pH greater
than 7.30 generally resolves with medical
A pH less than 7.20 indicates complicated
parapneumonic effusion (loculated or
associated with empyema), requiring
obtained by pericardiotomy following
limited thoracotomy or by
pericardiocentesis (sterile needle
Normal pericardial fluid is pale yellow
Large effusions (>350 mL) most often
caused by malignancy or uremia, or
may be idiopathic.
hallmarked by the development of
fever, pleuritic chest pain, and other
signs of pleural, pericardial, and, less
often, lung inflammation.
Exudative pleural effusions develop
in more than 80% of cases, often
serosanguineous to hemorrhagic and
typically have a pH greater than 7.4
and a normal glucose level.
Largest serosal sac in the body and secretes
approximately 50 ml of fluid per day.
Serum-Ascites Albumin Gradient
= serum albumin – ascites albumin
> 1.1 = portal hypertension
< 1.1 = non-portal hypertension
probably the best single method to
differentiate an ascitic exudate from a
Paracentesis ( so called tapping)
Diagnostic Peritoneal Lavage
Spontaneous bacterial peritonitis (SBP) is
an acute bacterial infection of ascitic fluid.
Patients with cirrhosis and ascites carry a
10% annual risk of ascitic fluid infection
Predisposing factor may be :
Intestinal bacterial overgrowth
Impaired phagocytic function
Low serum and ascites complement levels
Decreased activity of the reticuloendothelial
Etiologic agents (>90% intestinal flora)
Three forth of infections are due to aerobic gramnegative
One fourth are due to aerobic gram-positive
organisms (19% streptococcal species).
Anaerobic organisms are rare (1%) because of the
high oxygen tension of ascitic fluid.
Clinical presentation and diagnosis
of ascitic fluid infection
A broad range of symptoms and signs are seen in SBP. A high
index of suspicion must be maintained when caring for patients with
ascites, particularly those with acute clinical deterioration.
Completely asymptomatic cases in as many as 30% of patients.
Fever and chills occur in as many as 80% of patients.
Abdominal pain or discomfort is found in 70% of patients.
Worsening or unexplained encephalopathy
Diagnostic paracentesis and direct inoculation of routine
blood culture bottles at the bedside with 10 mL of ascitic
fluid must be performed.
The results of aerobic and anaerobic bacterial cultures,
used in conjunction with the cell count, prove the most
useful in guiding therapy for those with SBP.
An ascitic fluid neutrophil count of >500
cells/mL is the single best predictor of
Ascitic fluid examination
Appearance: The gross appearance of the ascitic fluid
can be helpful in the differential diagnosis.
Turbid or cloudy: infected fluid.
Milky: Triglyceride concentration of greater than 200mg/dl
(often greater than 1000mg/dl), malignancy is usually
MC cause, but cirrhosis may present with chylous fluid.
Pink or Bloody: Pink fluid usually traumatic tap. Frankly
bloody may occur in hepatocellular carcinoma, or other
malignancy related ascites.
Brown: Deeply jaundiced pts may present with brown
ascitic fluid, which may represent gallbladder rupture or
perforated duodenal ulcer.
• Total protein:
Helpful in diagnosing spontaneous bacterial
Pts with a value<1 g/dl protein and glucose
have high risk of SBP
for malignant cells
to exclude pancreatic ascites
Elevated alkaline phosphatase (ALP)
levels greater than 10 U/L in diagnostic
peritoneal lavage fluid are very useful in
predicting hollowvisceral injury in patients
who would otherwise not undergo
laparotomy (specificity 99.8%, sensitivity
peritoneal fluid LD has higher diagnostic
sensitivity (87%) and diagnostic accuracy
(90%) than serum LD
ADA is commonly used in endemic areas
to identify patients with tuberculous
Patients with hollow viscous
intestine, peritonitis, or intraabdominal
abscess have a peritoneal fluid minus
plasma lactate level of at least 13.5 mg/dL
(1.5 mmol/L), which separates
these patients completely from those with
other conditions producing acute abdominal