M5: Amniotic Fluid (Part 4: Tests for Fetal Maturity) Flashcards
(5) parameters measured/detected for fetal maturity
Condition associated with fetal maturity?
Respiratory Distress Syndrome (RDS)
(5) parameters measured/detected for fetal maturity?
- Amount of Surfactant
- Lecithin-shingomyelin ratio
- Phosphatidyl glycerol
- Foam stavility index
- Lamellar bodies
(5) parameters measured/detected for fetal maturity
- aka Hyaline Membrane Disease
- Most frequent complication of preterm delivery
- Caused by an insufficiency of lung surfactant production and structural immaturity of the fetal lungs
Respiratory distress syndrome
(5) parameters measured/detected for fetal maturity
Normally appears in mature lungs and allows the
alveoli (air sacs of the lung) to remain open throughout the normal cycle of inhalation and exhalation.
Surfactant
(5) parameters measured/detected for fetal maturity
keeps the alveoli from collapsing by decreasing
surface tension and allows them to inflate with air more easily
Surfactant
(5) parameters measured/detected for fetal maturity
The amount of surfactant in fetal lungs can be estimated by?
measuring amount of surfactants in amniotic fluid
(5) parameters measured/detected for fetal maturity
Reference method to which tests of FLM are compared
Lecithin-sphingomyelin ratio
(5) parameters measured/detected for fetal maturity
is the primary component of the surfactants
(phospholipids, neutral lipids, and proteins) that make up the alveolar lining and account for alveolar stability
Lecithin
(5) parameters measured/detected for fetal maturity
is a lipid that is produced at a constant rate
after about 26 weeks’ gestation; therefore, it can serve as a control on which to base the rise in lecithin
Sphingomyelin
(5) parameters measured/detected for fetal maturity
T or F
sphingomyelin only appear in the amniotic fluid in amounts proportional to their concentrations in the fetus
Lecithin-sphingomyelin ratio
F (BOTH lecithin and shingomyelin)
(5) parameters measured/detected for fetal maturity
Before or After 35 weeks of gestation?
L/S ratio is usually less than 1.6 because large
amounts of lecithin are not being produced at
this time.
Lecithin-sphingomyelin ratio
Before 35 weeks’ gestation
(5) parameters measured/detected for fetal maturity
Before or After 35 weeks of gestation?
Lecithin concentration increases while the
sphingomyelin concentration remains constant
Lecithin-sphingomyelin ratio
After 35 weeks of gestation
(5) parameters measured/detected for fetal maturity
The L/S ratio will rise to 2.0 or higher as the lecithin
production increases to prevent alveolar collapse
Lecithin-sphingomyelin ratio
After 35 weeks of gestation
(5) parameters measured/detected for fetal maturity
when the L/S ratio reaches 2.0, a preterm
delivery is usually considered to be a relatively safe procedure
Lecithin-sphingomyelin ratio
After 35 weeks of gestation
(5) parameters measured/detected for fetal maturity
when the L/S ratio reaches 2.0, this is usually considered to be a relatively safe procedure
Lecithin-sphingomyelin ratio
preterm delivery
(5) parameters measured/detected for fetal maturity
when the L/S ratio reaches 2.0, aside from preterm delivery, what is the other indication?
Lecithin-sphingomyelin ratio
Indicates fetal maturity
(5) parameters measured/detected for fetal maturity
Results encountered in fluid contaminated with blood or meconium
Lecithin-sphingomyelin ratio
Falsely elevated results
both these substances contain lecithin and sphingomyelin
(5) parameters measured/detected for fetal maturity
Quantitative measurement of lecithin and sphingomyelin is performed using?
Lecithin-sphingomyelin ratio
thin-layer chromatography (TLC)
(5) parameters measured/detected for fetal maturity
SInce L/S ratio is labor intensive and subject to high CV, what did laboratories replace L/S ratio with?
(2)
- quantitative phosphatidyl glycerol immunoassays
- lamellar body density procedures
(5) parameters measured/detected for fetal maturity
- is also essential for adequate lung maturity
and can be detected after 35 weeks’ gestation - normally parallels that of lecithin, but its production is delayed in cases of maternal diabete
Phosphatidyl glycerol
(5) parameters measured/detected for fetal maturity
respiratory distress occurs in the
presence of an L/S ratio of?
2.0
(5) parameters measured/detected for fetal maturity
must include lecithin, sphingomyelin, and PG to provide an accurate measurement of FLM.
Phosphatidyl glycerol
thin-layer chromatography lung profile
(5) parameters measured/detected for fetal maturity
has provided a more rapid and easy to perform method for assessment of fetal maturity
Phosphatidyl glycerol
immunologic agglutination test for PG
(5) parameters measured/detected for fetal maturity
uses antisera containing polyclonal anti-PG antibodies that are specific for PG- containing lamellar bodies in the amniotic fluid
Phosphatidyl glycerol
Amniostat-FLM
(5) parameters measured/detected for fetal maturity
sizes of agglutinates inAmniostat-FLm is read macroscopically and the results are reported as either?
Phosphatidyl glycerol
Negative, Low or high positive
(5) parameters measured/detected for fetal maturity
Amniostat-FLM result
pulmonary immaturity
Phosphatidyl glycerol
Negative
(5) parameters measured/detected for fetal maturity
Amniostat-FLM result
pulmonary maturity
Phosphatidyl glycerol
Low or high positive
(5) parameters measured/detected for fetal maturity
T or F
Amniostat-FLM is affected by specimen contamination with blood and meconium
Phosphatidyl glycerol
f (Amniostat-FLM is NOT affected by specimen contamination with blood and meconium)
(5) parameters measured/detected for fetal maturity
- called the “foam” or “shake” test
- used to determine the presence of individual lung- surface lipid concentrations
- can be performed at the bedside or in the laboratory
Foam stability index
(5) parameters measured/detected for fetal maturity
(1) In foam stability index amniotic fluid is mixed with?
Foam stability index
95% ethanol
(5) parameters measured/detected for fetal maturity
(2) After mixing, fluid is shaken for how many seconds?
Foam stability index
15 seconds
(5) parameters measured/detected for fetal maturity
(3) After shaking, it should be allowed to?
Foam stability index
sit undisturbed for 15 minutes
(5) parameters measured/detected for fetal maturity
At the end of this time, the surface of the fluid is
observed for the presence of?
Foam stability index
continuous line of bubbles around the outside edge
(5) parameters measured/detected for fetal maturity
indicates that a sufficient amount of phospholipid is available to reduce the surface tension of the fluid even in the presence of alcohol, an antifoaming agent
Foam stability index
Presence of bubbles
(5) parameters measured/detected for fetal maturity
Which is correct
modified foam test
a. 0.5 ul of amniotic fluid
b. 95% ethanol
c. 0.60 mL in 0.01 mL increments of ethanol
d. ALL
e. None
Foam stability index
b. 95% ethanol
a. 0.5 ul of amniotic fluid (should be mL)
c. 0.60 mL in 0.01 mL (should be 0.42-0.55 mL range)
(5) parameters measured/detected for fetal maturity
Reference value for foam stability index which indicates FLM?
Foam stability index
value of 47 or higher
>47
(5) parameters measured/detected for fetal maturity
T or F
The Foam Stability Index has shown good correlation with the L/S ratio and tests for phosphatidyl glycerol
Foam stability index
T
(5) parameters measured/detected for fetal maturity
T or F
Foam stability index can be used with contaminated amniotic fluid because blood and meconium also reduce surface tension, yielding a falsely mature index result
Foam stability index
F (cannot be used with contaminated amniotic fluid because blood and meconium also reduce surface tension, yielding a falsely mature index result)
(5) parameters measured/detected for fetal maturity
- These are densely packed layers of phospholipids that represent a storage form of pulmonary surfactant
- Similar to that of small platelets, ranging in size from 1.7 to 7.3 fL, or 1 to 5μm
Lamellar bodies
(5) parameters measured/detected for fetal maturity
Surfactant is composed of (blank) phospholipid and (blank) protein
Lamellar bodies
percentage
90% phospholipid, 10% protein
(5) parameters measured/detected for fetal maturity
Surfactant is packaged into layered storage granules called ?
lamellar bodies
(5) parameters measured/detected for fetal maturity
Lamellar bodies are secreted by?
type II pneumocytes of the fetal
lung at about 24 weeks of gestation
absorbed into the alveolar spaces to provide surfactant
(5) parameters measured/detected for fetal maturity
T or F
about 26 weeks of gestation and increase in concentration from 50,000 to 200,000 per microliter by the end of the third trimester
Lamellar bodies
T
(5) parameters measured/detected for fetal maturity
T or F
As the fetal lung matures, increased lamellar body production is reflected by an increase in amniotic fluid phospholipids and the L/S ratio
Lamellar bodies
T
(5) parameters measured/detected for fetal maturity
Directly proportional or inversely proportional?
No. of lamellar bodies = ?
Lamellar bodies
correlation with amount of phospholipid and L/S ratio
Directly proportional with phospholipids and L/S ratio
lamellar bodies present in the amniotic fluid correlates with the amount of phospholipid present in the fetal lungs
(5) parameters measured/detected for fetal maturity
T or F
The presence of lamellar bodies decreases the OD of the amniotic fluid.
F (The presence of lamellar bodies increases the OD of the amniotic fluid)
(5) parameters measured/detected for fetal maturity
Specimens are centrifuged at?
Lamellar bodies
2000 g for 10 minutes
(5) parameters measured/detected for fetal maturity
Specimens are examined using wavelength of?
Lamellar bodies
650 nm
(5) parameters measured/detected for fetal maturity
Reference value for lamellar body count which indicates FLM
Lamellar bodies
> 50,000/uL
(5) parameters measured/detected for fetal maturity
LBC value below 15,000/μL is considered?
Lamellar bodies
immature
Results in between these two values are considered indeterminate and further testing using alternate methods is recommended
(5) parameters measured/detected for fetal maturity
T or F
Lamellar body count procedure rules out interference and other contaminants such as meconium
F (does rule out pther interference but NOT other contaminants such as meconium)
SUMMARY
Determine test based on refrence value and significance:
Ref. value: A450 >.025
Significance: Hemolytic disease of the newborn
Bilirubin scan
Determine test based on refrence value and significance:
Ref. value: <2.0 MoM
Significance: Neural tube disorders
Alpha-fetoprotein
Determine test based on refrence value and significance:
Ref. value: ≥2.0
Significance: FLM
Lecithin-sphingomyelin
ratio
Determine test based on refrence value and significance:
Ref. value: Positive
Significance: FLM/PG
Fetal lung maturity/phosphatidyl glycerol
Amniostat fetal lung
maturity
Determine test based on refrence value and significance:
Ref. value: ≥47
Significance: FLM
Foam Stability Index
Determine test based on refrence value and significance:
Ref. value: ≥0.150
Significance: FLM
Optical density 650 nm
Determine test based on refrence value and significance:
Ref. value: ≥32,000/mL
Significance: FLM
Lamellar body count
