eval of body fluids Flashcards
what are the two types of effusion
- transudate
- exudate
what is a transudative effusion
- acumulation of fluid in a body cavity due to filtration of blood serum across a physiologically intact vascular wall
- due to pressure differences between body compartments
what is an exudative effusion
- accumulation of fluid within a body cavity due to inflammation and vascular damage
which type of effusion requires further testing? What conditions are being r/o?
- exudative
- infection: cultures
- malignancy: cytology
- inflammatory disorder
differentiate between transudative and exudative analysis in terms of protein fluid/serum ratio
- transudate: protein fluid/serum ratio < 0.5
- exudate: protein fluid/serum ratio > 0.5
differentiate between transudative and exudative analysis in terms of total protein levels
- transudative: total protein level < 3 g/dl
- exudative: total protein level > 3 g/dl
differentiate between transudative and exudative analysis in terms of color of fluid and number of WBC
- transudative: clear, thin fluid; WBC < 300/uL, mononuclear
- exudative: cloudy, thick, viscous fluid; WBC > 500/uL, neutrophils
differentiate between transudative and exudative analysis in terms of LDH fluid/serum ratio
- transudative: LDH fluid/serum ratio < 0.6
- exudate: LDH fluid/serum ratio > 0.6
differentiate between transudative and exudative analysis in terms of glucose concentration
- transudate: glucose equal to serum glucose
- exudate: glucose < serum glucose (< 60 mg/dl)
differentiate between transudative and exudative analysis in terms of pH
- transudate: pH = 7.4-7.5
- exudate: pH < or = 7.3-7.4
effusions with triglycerides/cholesterol can indicate?
- chylous effusion - thoracic duct impairtment: lymphoma, trauma, recent surgery
effusions with amylase can indicate
- esophageal rupture, pancreatitis, malignancy, bowel perforation
What are the most common causes of transudative pleural effusions
- CHF
- cirrhosis
- nephrosis
What are the most common causes of exudative pleural effusions
- parapneumonic effusion
- malignant effusion
What are the most common causes of parapneumonic effusion
- bacterial pneumonia
- lung abscess
- bronchiectasis
What are the most common causes of malignant effusions
- lung CA
- breast CA
- lymphoma
The following found in pleural effusion indicates what condition:
RBC > 100,000uL, Hct of fluid > or = 50% of peripheral blood smear, fluid is serosanginous in appearance.
hemothorax
What are the main causes of hemothorax
- trauma
- malignancy
- pulmonary embolism
what is empyema
- pus in pleural space
- WBC > 50,000 - 100,000
What type of cells would you expect to find in an empyema caused by inflammation/infection? caused by neoplasm or TB?
- inflammation/infection: > 50% neutrophils
- neoplasm or TB: >50% lymphocytes
Triglycerides seen in pleural fluid indicates
- chylous effusion seen in trauma, neoplasm, obstructed lymphatics
What is light’s criteria rule
- if at least one of the following three criteria is fulfilled, the fluid is defined as an exudate
- pleural fluid protein/serum protein ratio > 0.5
- pleural fluid LDH/serum LDH ratio >0.6
- pleural fluid LDH > 2/3rds of the upper limits of the lab’s normal serum LDH
a pulmonary embolism can cause what type of effusion?
either a transudative or exudative effusion
A parapneumonic effusion should be sampled if it meets any of the following criteria
- it layers out > 25 mm of a lateral decubitus film
- it is loculated
- it is associated with thickened parietal pleura on CT
- it is clearly delineated by US
Differential diagnosis of pericardial effusions
- acute pericarditis
- autoimmune disease
- post-MI, cardiac surgery
- chest trauma
- malignancy
- mediastinal radiation
- renal failure
- myxedema
- aortic dissection
When is pericardiocentesis indicated
- tamponade
- not indicated for pericardial effusion without tamponade unless fluid is needed for diagnostic purposes
What labs should you order when assessing pericardial fluid
- CBC
- CMP
- thyroid function
- ANA
- gram stain
- cultures
- cytology
what is ascites
accumulation of fluid within the peritoneal cavity
What are the two primary causes of ascites
- hepatic cirrhosis (81%)
- due to portal HTN
- malignancy (10%)
What is the gold standard for diagnosis peritoneal fluid-ascites
abd US
When is a abd paracentesis indicated
- new onset ascites or recurrent ascites
- fever
- abd tenderness (r/o peritonitis)
- mental status change
- hypotension
- peripheral leukocytosis
- worsening renal function
- GI bleed
What initial tests should you order on ascitic fluid
- culture and sensitivity
- albumin
- cell count with differential
- protein: amylase (along with serum amylase)
What is the SAAG classification?
- serum-to-ascites albumin gradient
- SAAG = (serum albumin) - (ascitic fluid albumin)
conditions leading to ascites through portal hypertension have a serum-to-ascites albumin gradient of
> 1.1 g/dL
conditions leading to ascites in the absence of portal hypertension (such as malignancy or infection) have a serum-to-ascites albumin gradient of
gradient < 1.1 g/dL
what is the WBC in the ascitic fluid in an uncomplicated cirrhosis
< 500 cell/uL
What is an extremely useful test in ascitic fluid analysis
ascitis fluid cell count
Patients with cirrhosis and ascites commonly get this condition?
clinical presentation
- abrupt onset of fevr, chills, abd pain
- rebound tenderness
- ascitic fluid WBC > 500 cells/uL with >50% neutrophils
spontaneous bacterial peritonitis
cerebrospinal fluid is produced where
produced by the choroid plexus
what is the most common collection technique for obtaining CSF
lumbar puncture
what are the diseases detected by CSF analysis
- hemorrhage
- infection
- miningitis
- abscess
- malignant process
- brain tumor
- leukemia or lymphoma
- multiple sclerosis
When is lumbar puncture contraindicated
increased intracranial pressure
- consider CT of head prior to LP
where in the vertebrae is the LP performed
- enter at L3-L4, L4-L5 interspace
- cauda equina terminates at L1-L2
What are some conditions that can cause a decreased CSF opening pressure
- hypovolemia (dehydration, shock), chronic CSF leak
What are some conditions that can cause a increased CSF opening pressure
- infection
- bleeding
- tumor
What are some conditions that can cause a large difference in CSF opening and closing pressure
spinal cord obstruction (tumor)
Indications for getting a CT before LP
- immunocompromised
- h/o CNS disease (mass, stroke)
- new onset sz (w/in 1 weeks)
- papilloedema
- ALOC
- focal neurologic deficit
describe normal CSF, color and opening pressure
- clear and colorless
- opening pressure 60-200 mmH2O, up to 250 in obese
what are the three tubes that are ordered to assess CSF
- chemistry analysis
- microbiology
- gram and acid fast stain, C & S
- hematology
- cell count and differential
xanthochromia
the yellow discoloration indicating the presence of bilirubin in the cerebrospinal fluid (CSF)
- indicates lysis of RBC
- hgb -> oxyhemoglobin -> methemoglobin -> biliruben
- present in > 90% of pts w/in 12 hours of subarachnoid hemorrhage
What is the normal range of CSF glucose? What conditions cause decrease and increase in levels?
2/3 of plasma glucose
- levels are decreased in bacterial meningitis and fungal infection
- levels are increased in hyperglycermia
presence of “oligo clonal bands” and “myeling basic protiens” are characteristic of
multiple sclerosis
What is the classic triad of symptoms in meningitis
- Altered mental status
- nuchal rigidity
- fever
- also can cause N/V, photophobia
- meningococcal can cause diffuse petechial rash
what is the gold standard in diagnosing causative organism in meningitis
CSF culture
Describe the method and function of KOH prep
- sample placed on slide with drop of KOH, slide is heated briefly with flame, then examined
- KOH dissolves host cells and bacteria, sparing fungi and elastin fibers
what slide is commonly used to diagnose herpes virus? describe the method
- Tzank prep
- slides prepared from lesion scrapings and stained with giemsa or wright
- presence of multinucleated giant cells indicates infection with HSV
what slide preparation is used for diagnosing CSF with cryptococci? what is the method
- india ink
- drop of centrifuged CSF is placed on slide next to drop of india ink
- cryptococci are identified by large capsules which exclude the ink
What methods are used to diagnose symphilis via direct identification of spirochetes
- dark field microscopy
- direct fluorescent antibody testing
- failure to identify organisms in specimen does not exclude primary symphilis **
which organism that causes syphilis can’t be cultured
Treponema pallidum
what antibody tests are done to diagnose syphillis
- non-treponemal is done first
- venereal disease research lab= use for CSF
- specific treponemal: done if (1) is positive
- confirmation of syphilis - T. pallidum enzyme immunoassay
what is expected to be seen in direct examination of coccidiomycosis (valley fever)
mature spherules with endospheres
what immunoglobulins respond to coccidiomycosis
igG and IgM
what detection techniques are used to detect specific etiologic agents in infectious disease
- latex agglutination
- enzyme immunoassay
- PCR
What is important about using the micro dilutation method in antimicrobial sensitivity
- gives minimum inhibitory concentration (MIC): the lowest concentration of Abx that inhibits visible growth of bacteria
What is important to remember when ordering blood cultures
- two different specimens must be ordered from two different sites
- if one is positive and other negative, + result is likely due to contaminant
- do not draw cultures from IV
- lab must be notified if Abx were initiated prior to the blood draw
differentiate between bacteremia and sepsis
- bacteremia: presence of organisms that be cultured from blood
- sepsis: presence of infection together with systemic manifestations of infection, can lead to organ dysfunction
What are the most common etiologic organisms causing sepsis? What organism has the highest mortality rate
- staphylcocci, streptococci,
- e-coli, enterbacter
- pseudomonas aeruginosa
- ***MRSA has the highest mortality rate
What Abx should be given initially in sepsis until cultures are available
empirical coverage of gram + and - organisms
what are the major risk factors for sepsis
- bacteremia
- age >65 yo
- immunosuppression
- DM
- malignancy
- community acquired PNA
- previous hospitalization (w/in 90 days)
clinical presentation
- temp > 38.3
- tachypnea, tachycardia
- AMS
- significant edema WBC > 12,000
- increased CRP, lactate
- thrombocytopenia
- hyperglycemia in absence of DM
- Cr > 0.5 mg/dL
- hypotension (<90/70)
- organ failure
sepsis
what is the definition of septic shock
sepsis induced hypotension that persists despite attempts at fluid resuscitation
