UA and body fluids unit 3 quizzes and ICA

A student asks why CSF is not simply an ultrafiltrate of plasma, even though it is formed from plasma. Which explanation is correct?

-CSF protein concentrations are identical to plasma protein concentrations

-CSF is formed entirely by passive diffusion with no selectivity

-The dura mater selectively filters plasma before it reaches the subarachnoid space

-The tight-fitting endothelial junctions of the choroid plexus capillaries (the blood-brain barrier) restrict free passage of many plasma molecules

The tight-fitting endothelial junctions of the choroid plexus capillaries (the blood-brain barrier) restrict free passage of many plasma molecules

A CSF specimen refrigerated overnight develops a web-like pellicle on the surface. This finding classically indicates:

-Tubercular meningitis

-A primary CNS malignancy

-Multiple sclerosis

-Viral meningitis

Tubercular meningitis

A patient has markedly elevated CSF total protein but a normal cell count and a clear, colorless specimen. This pattern is most consistent with:

- A traumatic tap

-A neurologic disorder such as Guillain-Barre syndrome, which can elevate protein without producing pleocytosis

-Bacterial meningitis

-Normal CSF

A neurologic disorder such as Guillain-Barre syndrome, which can elevate protein without producing pleocytosis

CSF lactate is sometimes considered more useful than glucose in equivocal meningitis cases. What is the best reason for this?

-Lactate is the only CSF chemical that correlates with protein concentration

-Lactate elevation occurs more consistently than decreased glucose, and lactate falls rapidly once antibiotic treatment becomes effective

-Lactate is unaffected by hemolysis, unlike glucose

-Glucose cannot be measured on automated chemistry analyzers

Lactate elevation occurs more consistently than decreased glucose, and lactate falls rapidly once antibiotic treatment becomes effective

A fluid specimen submitted as "CSF" is of questionable origin. Which finding would help confirm that the fluid is truly CSF?

- Presence of IgM, since IgM is unique to CSF

-A protein concentration greater than 100 mg/dL

-Presence of the tau transferrin (carbohydrate-deficient transferrin) fraction, which is unique to CSF

-Presence of albumin, since albumin is found only in CSF

Presence of the tau transferrin (carbohydrate-deficient transferrin) fraction, which is unique to CSF

Why should a blood glucose specimen be drawn approximately 2 hours before a scheduled lumbar puncture?

-Blood glucose cannot be measured on the same day as a lumbar puncture

-The 2-hour window has no clinical purpose and is only a scheduling convention

-To allow the patient to fast, which is required before CSF collection

-To allow time for equilibration between blood and CSF glucose, so a valid comparison can be made

To allow time for equilibration between blood and CSF glucose, so a valid comparison can be made

Three tubes of CSF are collected from a patient; blood is heaviest in Tube 1 and progressively clears by Tube 3. This pattern is most consistent with:

-A traumatic tap

-Multiple sclerosis

-Bacterial meningitis

-An intracranial hemorrhage

A traumatic tap

A Gram stain of CSF from a neonate shows gram-positive rods. The most likely organism is:

-Neisseria meningitidis

-Listeria monocytogenes

-Escherichia coli

-Streptococcus pneumoniae

Listeria monocytogenes

A patient's CSF results show a normal glucose, a lymphocyte predominance, mildly elevated protein, and a lactate of 15 mg/dL. This pattern is most consistent with:

-A traumatic tap

-Tubercular meningitis

-Viral meningitis

-Bacterial meningitis

Viral meningitis

A CSF specimen forms a visible clot shortly after collection. This finding is most consistent with:

-A traumatic tap, which introduced plasma fibrinogen into the specimen

-Normal CSF, since clotting is an expected finding

-Tubercular meningitis, which always produces clot formation at the time of collection

-An intracranial hemorrhage, which does not typically contain enough fibrinogen to clot

A traumatic tap, which introduced plasma fibrinogen into the specimen

A CSF differential shows a predominance of neutrophils, many containing phagocytized bacteria. This picture is most consistent with:

-Multiple sclerosis

-A CNS malignancy

-Normal CSF cytology

-Bacterial meningitis

Bacterial meningitis

What is the main advantage of PCR (nucleic acid amplification) testing over traditional culture for identifying the cause of meningitis?

-It can detect the pathogen's DNA with high sensitivity and specificity in a fraction of the time culture requires, without needing a large number of viable organisms

-It eliminates the need to ever perform a Gram stain

-It directly measures the patient's CSF glucose and protein at the same time

-It is less expensive than every other microbiology method

It can detect the pathogen's DNA with high sensitivity and specificity in a fraction of the time culture requires, without needing a large number of viable organisms

A patient who recently swam in a warm freshwater lake develops rapidly progressive meningoencephalitis. Motile trophozoites with an elongated, tapered posterior are seen on a wet preparation of CSF. The most likely organism is:

-Cryptococcus neoformans

-Naegleria fowleri

-Mycobacterium tuberculosis

-Listeria monocytogenes

 

Naegleria fowleri

A CSF specimen appears visibly milky. What is the most likely explanation for this appearance?

-A markedly increased lipid or protein concentration

-Normal variation requiring no further workup

-Early RBC degradation products

-A mild increase in WBCs only

A markedly increased lipid or protein concentration

A Gram stain of CSF from an adult with suspected bacterial meningitis shows gram-positive, lancet-shaped diplococci. The most likely organism is:

- Neisseria meningitidis

- Escherichia coli

-Listeria monocytogenes

-Streptococcus pneumoniae

Streptococcus pneumoniae

What is the primary clinical utility of measuring myelin basic protein (MBP) in the CSF?

-It confirms that a fluid specimen is truly CSF

-It is used to calculate the CSF/serum albumin index

-It identifies the causative organism in bacterial meningitis

-It indicates recent demyelination and can be used to monitor multiple sclerosis disease activity and treatment effectiveness

It indicates recent demyelination and can be used to monitor multiple sclerosis disease activity and treatment effectiveness

Prior to spinal tap (~4 hours prior), a patient experienced a subarachnoid hemorrhage. Would xanthochromia be expected in the supernatant?

-Yes, RBC degradation in the CSF post-hemorrhage can produce xanthochromia

-Yes, but only if the patient is a neonate

-No, xanthochromia never develops from RBC degradation

-No, RBCs typically must be present for less than 2 hours before noticeable hemolysis produces xanthochromia

Yes, RBC degradation in the CSF post-hemorrhage can produce xanthochromia

A patient's CSF/serum albumin index is calculated to be 14. How should this result be interpreted?

-The result is invalid and must be repeated

-IgG is being synthesized within the CNS

-The blood-brain barrier is damaged, since a value greater than 9 indicates barrier damage

-The blood-brain barrier is intact

The blood-brain barrier is damaged, since a value greater than 9 indicates barrier damage

Nucleated RBCs along with capillary and endothelial structures are seen on a CSF smear. The most likely explanation is:

-Contamination from bone marrow introduced during the puncture procedure

-Chronic tubercular meningitis

-A primary hematologic malignancy involving the CNS

-A normal finding expected in every CSF specimen

Contamination from bone marrow introduced during the puncture procedure

A patient's CSF IgG index is calculated to be 1.2. How should this result be interpreted?

- No IgG is present in the CSF

-The blood-brain barrier is intact

-IgG is being synthesized within the CNS, since a value greater than 0.70 supports this

-The result indicates a traumatic tap

IgG is being synthesized within the CNS, since a value greater than 0.70 supports this

A patient with a recently placed ventricular shunt has increased eosinophils on CSF differential. The most likely explanation is:

- Multiple sclerosis

-A reaction to the foreign shunt material (or an underlying parasitic/fungal process)

-Bacterial meningitis

-A traumatic tap

A reaction to the foreign shunt material (or an underlying parasitic/fungal process)

What is the primary clinical utility of measuring myelin basic protein (MBP) in the CSF?

-It confirms that a fluid specimen is truly CSF

-It identifies the causative organism in bacterial meningitis

-It indicates recent demyelination and can be used to monitor multiple sclerosis disease activity and treatment effectiveness

-It is used to calculate the CSF/serum albumin index

It indicates recent demyelination and can be used to monitor multiple sclerosis disease activity and treatment effectiveness

A Gram stain of CSF from a neonate shows gram-positive rods. The most likely organism is:

-Escherichia coli

-Listeria monocytogenes

-Streptococcus pneumoniae

-Neisseria meningitidis

Listeria monocytogenes

Prior to spinal tap (~4 hours prior), a patient experienced a subarachnoid hemorrhage. Would xanthochromia be expected in the supernatant?

-No, RBCs typically must be present for less than 2 hours before noticeable hemolysis produces xanthochromia

-Yes, but only if the patient is a neonate

-No, xanthochromia never develops from RBC degradation

-Yes, RBC degradation in the CSF post-hemorrhage can produce xanthochromia

Yes, RBC degradation in the CSF post-hemorrhage can produce xanthochromia

A patient has markedly elevated CSF total protein but a normal cell count and a clear, colorless specimen. This pattern is most consistent with:

-A traumatic tap

-Bacterial meningitis

-A neurologic disorder such as Guillain-Barre syndrome, which can elevate protein without producing pleocytosis

-Normal CSF

A neurologic disorder such as Guillain-Barre syndrome, which can elevate protein without producing pleocytosis

Why should a CSF cell count ideally be performed within about 1 hour when the specimen is held at room temperature?

-The specimen will clot and become unusable after 1 hour

-Glucose in the specimen will crystallize after 1 hour

-Bacteria present will overgrow and invalidate the microbiology culture

-WBCs (particularly granulocytes) and RBCs begin to lyse quickly, which falsely lowers the cell count if testing is delayed

WBCs (particularly granulocytes) and RBCs begin to lyse quickly, which falsely lowers the cell count if testing is delayed

Two oligoclonal bands are detected in a patient's CSF by electrophoresis, while a simultaneous serum electrophoresis shows no bands. This finding is best interpreted as:

- Immunoglobulin leaking into the CSF from the serum through an intact blood-brain barrier

-A normal, expected CSF electrophoresis pattern

-Evidence of a traumatic tap

-Immunoglobulin production occurring within the CNS itself, supporting a diagnosis such as multiple sclerosis

Immunoglobulin production occurring within the CNS itself, supporting a diagnosis such as multiple sclerosis

Nucleated RBCs along with capillary and endothelial structures are seen on a CSF smear. The most likely explanation is:

-A primary hematologic malignancy involving the CNS

-Chronic tubercular meningitis

-A normal finding expected in every CSF specimen

-Contamination from bone marrow introduced during the puncture procedure

Contamination from bone marrow introduced during the puncture procedure

A MLS omits the albumin step before cytocentrifuging a CSF specimen. What is the most likely consequence?

-Inability to perform a Gram stain on the same slide

-No effect, since albumin is only a historical step with no functional purpose

-Falsely increased WBC count

-Decreased cell yield and increased cellular distortion on the resulting smear

Decreased cell yield and increased cellular distortion on the resulting smear

Tube 1, the first tube collected during a lumbar puncture, is conventionally sent to chemistry and serology rather than microbiology or hematology. What is the best explanation for this convention?

-Serologic tests cannot be performed on any tube other than the first

-Chemical and serological test results are the least affected by blood or bacteria introduced during the tap, unlike cell counts or cultures

-Chemistry testing requires the largest specimen volume, so it must be collected first

-Tube 1 is always the least contaminated by blood or bacteria introduced during needle insertion

Chemical and serological test results are the least affected by blood or bacteria introduced during the tap, unlike cell counts or cultures

A patient who recently swam in a warm freshwater lake develops rapidly progressive meningoencephalitis. Motile trophozoites with an elongated, tapered posterior are seen on a wet preparation of CSF. The most likely organism is:

-Mycobacterium tuberculosis

-Naegleria fowleri

-Listeria monocytogenes

-Cryptococcus neoformans

Naegleria fowleri

A patient's CSF IgG index is calculated to be 1.2. How should this result be interpreted?

-The blood-brain barrier is intact

-No IgG is present in the CSF

-IgG is being synthesized within the CNS, since a value greater than 0.70 supports this

-The result indicates a traumatic tap

IgG is being synthesized within the CNS, since a value greater than 0.70 supports this

A patient's CSF/serum albumin index is calculated to be 14. How should this result be interpreted?

-The result is invalid and must be repeated

-The blood-brain barrier is intact

-The blood-brain barrier is damaged, since a value greater than 9 indicates barrier damage

-IgG is being synthesized within the CNS

The blood-brain barrier is damaged, since a value greater than 9 indicates barrier damage

A full-term neonate's CSF shows 22 mononuclear cells/µL, no neutrophils, and a negative Gram stain. How should this result be interpreted?

-Within the expected normal range for a neonate, who may normally have up to 30 mononuclear cells/µL

-Diagnostic of a traumatic tap

-Diagnostic of viral meningitis

-Abnormal - any CSF WBC count above 5/µL is pathologic regardless of patient age

Within the expected normal range for a neonate, who may normally have up to 30 mononuclear cells/µL

A patient's CSF results show markedly decreased glucose, a neutrophil predominance, elevated protein, and a lactate of 45 mg/dL. This pattern is most consistent with:

-Viral meningitis

-Multiple sclerosis

-A normal CSF profile

-Bacterial meningitis

Bacterial meningitis

A CSF specimen appears visibly milky. What is the most likely explanation for this appearance?

-Early RBC degradation products

-A markedly increased lipid or protein concentration

-Normal variation requiring no further workup

-A mild increase in WBCs only

A markedly increased lipid or protein concentration

A cryptococcal antigen latex agglutination test on a patient's CSF is positive, but the result is later determined to be a false positive. What is the most common cause of this type of false-positive reaction?

-Interference by hemoglobin

-Interference by elevated CSF glucose

-Interference by bilirubin

-Interference by rheumatoid factor

Interference by rheumatoid factor

A CSF differential shows a predominance of neutrophils, many containing phagocytized bacteria. This picture is most consistent with:

-Bacterial meningitis

-A CNS malignancy

-Normal CSF cytology

-Multiple sclerosis

Bacterial meningitis

A CSF specimen refrigerated overnight develops a web-like pellicle on the surface. This finding classically indicates:

-Multiple sclerosis

-A primary CNS malignancy

-Tubercular meningitis

-Viral meningitis

Tubercular meningitis

A patient's plasma glucose is 120 mg/dL. Assuming a normal blood-brain barrier, the CSF glucose would be expected to fall in approximately which range?

-72 to 84 mg/dL

-118 to 122 mg/dL, essentially equal to plasma

-20 to 30 mg/dL

-100 to 110 mg/dL

72 to 84 mg/dL

Why should a blood glucose specimen be drawn approximately 2 hours before a lumbar puncture when CSF glucose will be evaluated?

-To allow time for the blood glucose to drop to fasting levels

-To allow equilibration between the blood and CSF glucose for a valid comparison

-Because glucose is unstable in CSF and must be measured first

-Because the lumbar puncture itself transiently raises blood glucose

To allow equilibration between the blood and CSF glucose for a valid comparison

Which CSF tube is typically designated for the microbiology laboratory?

-Tube 1

-Tube 2

-Tube 3

-Tube 4

Tube 2

Approximately what percentage of the plasma glucose value does a normal CSF glucose represent?

-10% to 20%

-40% to 50%

-60% to 70%

-90% to 100%

60% to 70%

Between which vertebrae is a lumbar puncture routinely performed to collect CSF?

-T10-T11

-L1-L2

-L3-L4 or L4-L5

-S1-S2

L3-L4 or L4-L5

The CSF/serum albumin index is used primarily to evaluate:

-The integrity of the blood-brain barrier

-Immunoglobulin synthesis within the CNS

-The presence of oligoclonal bands

-Recent myelin sheath destruction

The integrity of the blood-brain barrier

A CSF specimen shows markedly decreased glucose relative to plasma, increased protein, a neutrophil-predominant differential, and a lactate of 40 mg/dL. These findings are most consistent with:

-Bacterial meningitis

-Viral meningitis

-Multiple sclerosis

-A traumatic tap

Bacterial meningitis

A CSF differential reveals numerous macrophages containing ingested RBCs (erythrophagocytosis). This finding most strongly supports:

-A prior hemorrhage into the CSF

-Bacterial meningitis

-Bone marrow contamination from the puncture

-A parasitic CNS infection

A prior hemorrhage into the CSF

Why is CSF lactate often considered a more reliable indicator than glucose when diagnosing bacterial, tubercular, or fungal meningitis?

-Lactate elevation occurs more consistently across these meningitis types than decreased glucose does

-Lactate results are unaffected by hemolysis of the specimen

-Lactate requires no comparison to a paired serum or plasma value

-Lactate is elevated only in viral meningitis, making it highly specific

Lactate elevation occurs more consistently across these meningitis types than decreased glucose does

Naegleria fowleri, a free-living amoeba that can cause fatal meningoencephalitis, typically enters the body through which route?

-The nasal passages, migrating along the olfactory nerves to the brain

-Direct bloodstream inoculation via an insect bite

-Ingestion of contaminated water

-Penetration through open skin wounds exposed to soil

The nasal passages, migrating along the olfactory nerves to the brain

Why is the CSF cell count typically performed on Tube 3 rather than Tube 1?

-Tube 3 is least likely to contain cells or skin-flora debris introduced by the puncture procedure itself

-Tube 3 has the highest protein concentration of the three tubes

-Tube 3 is collected first and is therefore the freshest specimen

-Tube 3 must be frozen before cell counting can be performed

Tube 3 is least likely to contain cells or skin-flora debris introduced by the puncture procedure itself

A CSF specimen shows blood that is heaviest in Tube 1 and progressively clears by Tube 3, with a clear supernatant after centrifugation. This pattern is most consistent with:

-A traumatic tap

-A subarachnoid hemorrhage

-Bacterial meningitis

-Multiple sclerosis

A traumatic tap

If testing cannot be performed immediately, how should the CSF tube designated for microbiology be stored?

-Refrigerated up to 4 hours

-At room temperature

-Frozen

-On wet ice in a slurry

At room temperature

A weblike pellicle forms in a CSF specimen after overnight refrigeration. This finding is classically associated with:

-Multiple sclerosis

-Bacterial meningitis

-Tubercular meningitis

-Viral meningitis

 

Tubercular meningitis

What is the normal adult reference range for CSF WBC count?

-0 to 5 WBCs/µL

-5 to 10 WBCs/µL

-10 to 30 WBCs/µL

-30 to 50 WBCs/µL

 

0 to 5 WBCs/µL

A patient's CSF IgG index is calculated to be 1.1 (reference: less than 0.70 is normal). This result indicates:

-IgG is being synthesized within the central nervous system

-The blood-brain barrier is intact and functioning normally

-The patient has bacterial meningitis

-The CSF/serum albumin index was calculated incorrectly

IgG is being synthesized within the central nervous system

Clusters of cells with distinct cytoplasmic borders and uniform nuclei, resembling choroid plexus or ependymal cells, are seen in a CSF differential shortly after a ventricular shunt procedure. These cells should be interpreted as:

-Malignant cells of nonhematologic origin

-Evidence of bacterial meningitis

-Nonpathologically significant

-Evidence of a traumatic tap

Nonpathologically significant

Why is albumin added to a CSF specimen before cytocentrifugation?

-It increases cellular yield and decreases distortion of the cells

-It prevents clot formation during the centrifugation step

-It lowers specimen pH for optimal Wright stain uptake

-It reduces the risk of microbial contamination of the slide

It increases cellular yield and decreases distortion of the cells

Which CSF protein fraction is unique to CSF (not normally present in serum) and can help confirm that an unidentified fluid specimen is truly CSF?

-Albumin

-Myelin basic protein

-Tau transferrin

-Transthyretin

Tau transferrin

Why does a xanthochromic supernatant typically NOT appear immediately following a traumatic tap?

-RBCs must be present for approximately 2 hours before hemolysis/degradation products accumulate

-Traumatic taps always clot before centrifugation can occur

-Xanthochromia only develops in neonatal CSF specimens

-A traumatic tap introduces WBCs rather than RBCs into the specimen

RBCs must be present for approximately 2 hours before hemolysis/degradation products accumulate

A Gram stain of CSF from an adult with bacterial meningitis shows gram-positive diplococci. Which organism is most likely responsible?

-Streptococcus pneumoniae

-Neisseria meningitidis

-Haemophilus influenzae

-Escherichia coli

Streptococcus pneumoniae

A MLS is told that 40 mL of fluid was aspirated from a patient's knee. How should this volume be interpreted?

-It is within the normal volume for a knee joint

-It confirms that the fluid is septic

-It is well above the normal volume and indicates an effusion, possibly from inflammation

-It confirms that the fluid is a traumatic tap

It is well above the normal volume and indicates an effusion, possibly from inflammation

A synovial fluid lactate is 12 mmol/L while the Gram stain result is pending. What should the laboratory do?

-Disregard it because lactate only reflects rheumatoid arthritis severity

-Wait for the culture results before reporting any value

-Notify the physician promptly, because this level suggests bacterial arthritis requiring immediate treatment

-Report it as normal because lactate is not elevated in infection

Notify the physician promptly, because this level suggests bacterial arthritis requiring immediate treatment

A synovial fluid glucose is 55 mg/dL for a fasting patient whose simultaneous blood glucose is 98 mg/dL. What is the best interpretation?

-The fluid glucose is increased and indicates a noninflammatory process

-The fluid glucose is within 10 mg/dL of blood and is normal

-The fluid glucose is not clinically useful because synovial fluid does not contain glucose

-The fluid glucose is markedly decreased relative to blood, suggesting an inflammatory or septic process

The fluid glucose is markedly decreased relative to blood, suggesting an inflammatory or septic process

A control slide for the detection of monosodium urate crystals is prepared with which material?

-Powdered EDTA

-Cholesterol plates

-Betamethasone acetate

-Starch granules

Betamethasone acetate

Two specimens are blood tinged. Specimen A has uneven streaks of blood, while Specimen B is uniformly bloody. Which statement is correct?

-Specimen A is more consistent with a true hemorrhagic joint disorder, whereas Specimen B suggests a traumatic tap

-Both specimens are consistent with a septic joint

-Specimen B is more consistent with a true hemorrhagic joint disorder, whereas Specimen A suggests a traumatic tap

-Both specimens are consistent with a crystal-induced disorder

Specimen B is more consistent with a true hemorrhagic joint disorder, whereas Specimen A suggests a traumatic tap

Needle-shaped, strongly birefringent crystals appear yellow when aligned parallel to the slow axis of the red compensator. Which crystal and birefringence are present?

-Monosodium urate with negative birefringence

-Monosodium urate with positive birefringence

-Calcium pyrophosphate dihydrate with negative birefringence

-Calcium pyrophosphate dihydrate with positive birefringence

Monosodium urate with negative birefringence

When is PCR most useful in the evaluation of synovial fluid infection?

-When the technologist needs to identify monosodium urate crystals

-When the cell count must be performed on a clotted specimen

-When fastidious or slow-growing organisms such as Borrelia burgdorferi or Mycobacterium tuberculosis are suspected

-When the Gram stain and culture are routinely replaced by PCR for every specimen

When fastidious or slow-growing organisms such as Borrelia burgdorferi or Mycobacterium tuberculosis are suspected

A 50-year-old man has a milky joint fluid, a markedly elevated serum uric acid, and needle-shaped, strongly birefringent crystals that are yellow when parallel to the slow axis. The patient also has a fever. Which action is most appropriate?

-Report the findings as gout only because crystals rule out infection

-Also perform Gram stain and culture, because infection can accompany crystal-induced arthritis

-Report the crystals as CPPD because the fluid is milky

-Discard the specimen because crystals and fever cannot coexist

Also perform Gram stain and culture, because infection can accompany crystal-induced arthritis

A MLS identifies vacuolated macrophages containing ingested neutrophils on a cytospin slide. What are these cells called?

-Mesothelial cells

-Reiter cells (neutrophages)

-Ragocytes

-Synoviocytes that are normal and not clinically significant

Reiter cells (neutrophages)

A MLS counts 63 cells in all nine large squares of a Neubauer chamber using a 1:2 dilution with saline. What is the WBC count (cells/uL)?

-70

-140

-126

-1,400

140

Weakly birefringent, rhomboid crystals located inside neutrophil vacuoles appear blue when parallel to the slow axis. Which crystal and disease are most likely?

-Monosodium urate; gout

-Calcium oxalate; renal dialysis

-Cholesterol; rheumatoid arthritis

-Calcium pyrophosphate dihydrate; pseudogout

Calcium pyrophosphate dihydrate; pseudogout

Which statement best explains why monosodium urate crystals appear yellow when aligned with the slow vibration axis?

-The crystals are not birefringent, so only the background color is seen

-The molecules run parallel to the long axis of the crystal and impede the fast light

-The molecules run perpendicular to the long axis of the crystal and impede the slow light

-The crystals absorb all light except yellow wavelengths from the compensator

The molecules run parallel to the long axis of the crystal and impede the fast light

A patient has clinical signs of a joint infection, but the synovial fluid lactate is normal. Which organism is a recognized exception that may produce a normal or low lactate?

-Haemophilus influenzae

-Staphylococcus aureus

-Neisseria gonorrhoeae

-Streptococcus species

Neisseria gonorrhoeae

A sexually active 22-year-old has an acutely painful knee, and Gram stain of the fluid shows gram-negative diplococci within neutrophils. Which medium is especially important for culture?

-Sabouraud dextrose agar

-Xylose lysine deoxycholate agar

-MacConkey agar

-Chocolate agar

Chocolate agar

Which laboratory finding best separates an inflammatory joint fluid from a noninflammatory fluid?

-A WBC count below 200/uL

-A viscosity that is equal to normal

-A markedly decreased glucose relative to the blood glucose together with an increased WBC count

-A normal glucose relative to the blood glucose

A markedly decreased glucose relative to the blood glucose together with an increased WBC count

A knee aspirate is received in three tubes. Which tube-test pairing is most appropriate?

-Plain nonanticoagulated tube for the cell count

-Sterile heparin or SPS tube for Gram stain and culture

-Sodium fluoride tube for Gram stain and culture

-Powdered EDTA tube for the cell count and crystal examination

Sterile heparin or SPS tube for Gram stain and culture

A rheumatology clinic asks why crystal examinations should be done as soon as possible after collection. What is the best explanation?

-Hyaluronic acid precipitates and traps the crystals in a clot

-Bacteria in the fluid convert urate crystals into calcium pyrophosphate

-Crystals become more birefringent with time, causing false-positive results

-Crystals can change or dissolve and cells can disintegrate during storage, so results may be altered

Crystals can change or dissolve and cells can disintegrate during storage, so results may be altered

A synovial fluid has a WBC count of 150/uL with 15% neutrophils and mostly monocytes, macrophages, and synovial lining cells. How should these results be interpreted?

-They fall within expected normal limits

-They indicate hemorrhage into the joint

-They indicate an inflammatory process because neutrophils are present

-They indicate septic arthritis

They fall within expected normal limits

A synovial fluid is milky but contains relatively few WBCs. Which cause of the milky appearance should the MLS investigate first?

-Contamination with sodium fluoride

-Fresh hemorrhage into the joint

-Crystals in suspension

-Normal hyaluronic acid content

Crystals in suspension

A MLS rotates a needle-shaped urate crystal so that its long axis is perpendicular to the slow axis of the compensator. What color is expected?

-Red

-Yellow

-Blue

-Colorless

Blue

A synovial fluid glucose is 55 mg/dL for a fasting patient whose simultaneous blood glucose is 98 mg/dL. What is the best interpretation?

-The fluid glucose is within 10 mg/dL of blood and is normal

-The fluid glucose is not clinically useful because synovial fluid does not contain glucose

-The fluid glucose is increased and indicates a noninflammatory process

-The fluid glucose is markedly decreased relative to blood, suggesting an inflammatory or septic process

The fluid glucose is markedly decreased relative to blood, suggesting an inflammatory or septic process

A MLS examining an unstained wet preparation of synovial fluid sees numerous small, sharp, refractile particles that polarize light. The fluid was collected in a tube containing a powdered anticoagulant. What is the best interpretation?

-The particles are CPPD crystals and the patient has pseudogout

-The particles are likely artifacts from the powdered anticoagulant and should not be reported as crystals

-The particles are monosodium urate crystals and the patient has gout

-The particles are corticosteroid crystals from a recent joint injection

 

The particles are likely artifacts from the powdered anticoagulant and should not be reported as crystals

A synovial fluid total protein is 5 g/dL. How should this result be interpreted?

-It is within normal limits

-It is above the normal limit and is associated with inflammatory or hemorrhagic disorders

-It rules out septic arthritis

-It is diagnostic of gout

It is above the normal limit and is associated with inflammatory or hemorrhagic disorders

Which approach best minimizes the chance of mistaking dust, scratches, or starch for crystals?

-Add acetic acid to the slide to dissolve any artifacts

-Stain every slide with Wright stain before viewing

-Examine a wet preparation made with clean slides and coverslips and compare findings with patient history

-Use powdered anticoagulant to preserve the crystals

Examine a wet preparation made with clean slides and coverslips and compare findings with patient history

A MLS identifies vacuolated macrophages containing ingested neutrophils on a cytospin slide. What are these cells called?

-Mesothelial cells

-Reiter cells (neutrophages)

-Ragocytes

-Synoviocytes that are normal and not clinically significant

Reiter cells (neutrophages)

A knee aspirate is received in three tubes. Which tube-test pairing is most appropriate?

-Plain nonanticoagulated tube for the cell count

-Sodium fluoride tube for Gram stain and culture

-Sterile heparin or SPS tube for Gram stain and culture

-Powdered EDTA tube for the cell count and crystal examination

Sterile heparin or SPS tube for Gram stain and culture

A patient with hemophilia presents with a swollen, painful knee, and the aspirate is uniformly bloody. Which classification best fits this fluid?

-Noninflammatory

-Septic

-Crystal-induced inflammatory

-Hemorrhagic

Hemorrhagic

Which statement best explains why monosodium urate crystals appear yellow when aligned with the slow vibration axis?

-The crystals absorb all light except yellow wavelengths from the compensator

-The molecules run parallel to the long axis of the crystal and impede the fast light

-The molecules run perpendicular to the long axis of the crystal and impede the slow light

-The crystals are not birefringent, so only the background color is seen

The molecules run parallel to the long axis of the crystal and impede the fast light

When is PCR most useful in the evaluation of synovial fluid infection?

-When fastidious or slow-growing organisms such as Borrelia burgdorferi or Mycobacterium tuberculosis are suspected

-When the cell count must be performed on a clotted specimen

-When the Gram stain and culture are routinely replaced by PCR for every specimen

-When the technologist needs to identify monosodium urate crystals

When fastidious or slow-growing organisms such as Borrelia burgdorferi or Mycobacterium tuberculosis are suspecte

A synovial fluid is milky but contains relatively few WBCs. Which cause of the milky appearance should the MLS investigate first?

-Crystals in suspension

-Contamination with sodium fluoride

-Normal hyaluronic acid content

-Fresh hemorrhage into the joint

Crystals in suspension

Macrophages containing brown, refractile granules of hemosiderin are seen in a synovial fluid differential. With which condition are these findings associated?

- Septic arthritis caused by Staphylococcus

-Gout

-Corticosteroid injection

-Pigmented villonodular synovitis

Pigmented villonodular synovitis

A control slide for the detection of monosodium urate crystals is prepared with which material?

-Cholesterol plates

-Starch granules

-Powdered EDTA

-Betamethasone acetate

Betamethasone acetate

A patient has clinical signs of a joint infection, but the synovial fluid lactate is normal. Which organism is a recognized exception that may produce a normal or low lactate?

- Neisseria gonorrhoeae

-Streptococcus species

-Haemophilus influenzae

-Staphylococcus aureus

Neisseria gonorrhoeae

A patient on long-term renal dialysis has joint pain, and crystals are found in the synovial fluid. Which crystal is most likely associated with this history?

-Calcium oxalate

-Corticosteroid

-Monosodium urate

-Cholesterol

Calcium oxalate

A MLS is told that 40 mL of fluid was aspirated from a patient's knee. How should this volume be interpreted?

-It confirms that the fluid is septic

-It is within the normal volume for a knee joint

It confirms that the fluid is a traumatic tap

It is well above the normal volume and indicates an effusion, possibly from inflammation

A sexually active 22-year-old has an acutely painful knee, and Gram stain of the fluid shows gram-negative diplococci within neutrophils. Which medium is especially important for culture?

-Chocolate agar

-MacConkey agar

-Sabouraud dextrose agar

-Xylose lysine deoxycholate agar

Chocolate agar

Which crystal characteristic best helps distinguish gout from pseudogout on a routine wet preparation viewed under polarized light?

-MSU crystals are needle shaped and more brightly birefringent than the rhomboid, weakly birefringent CPPD crystals

-Both crystals are nonbirefringent and are identified by stain

-Both crystals are needle shaped and cannot be separated on shape

-MSU crystals are rhomboid and less brightly birefringent than needle-shaped CPPD crystals

MSU crystals are needle shaped and more brightly birefringent than the rhomboid, weakly birefringent CPPD crystals

A clear, deeper-yellow synovial fluid is received from a patient with joint swelling. What does this appearance most likely represent?

-A normal synovial fluid

-A bacterial infection, because infected fluid is always yellow

-An effusion associated with a noninflammatory or inflammatory process

-A traumatic tap

An effusion associated with a noninflammatory or inflammatory process

A MLS counts 63 cells in all nine large squares of a Neubauer chamber using a 1:2 dilution with saline. What is the WBC count (cells/uL)?

-1,400

-70

-126

-140

140

A synovial fluid has 12,000 WBC/uL with predominantly lymphocytes, a glucose of 40 mg/dL (blood glucose 95 mg/dL), and ragocytes. Which classification and condition fit best?

-Septic; bacterial arthritis

-Inflammatory; rheumatoid arthritis

-Hemorrhagic; hemophilia

-Noninflammatory; osteoarthritis

Inflammatory; rheumatoid arthritis