M5: Amniotic Fluid (Part 4: Tests for Fetal Maturity) Flashcards

1
Q

(5) parameters measured/detected for fetal maturity

Condition associated with fetal maturity?

A

Respiratory Distress Syndrome (RDS)

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2
Q

(5) parameters measured/detected for fetal maturity?

A
  1. Amount of Surfactant
  2. Lecithin-shingomyelin ratio
  3. Phosphatidyl glycerol
  4. Foam stavility index
  5. Lamellar bodies
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3
Q

(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
A

Respiratory distress syndrome

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4
Q

(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.

A

Surfactant

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5
Q

(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

A

Surfactant

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6
Q

(5) parameters measured/detected for fetal maturity

The amount of surfactant in fetal lungs can be estimated by?

A

measuring amount of surfactants in amniotic fluid

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7
Q

(5) parameters measured/detected for fetal maturity

Reference method to which tests of FLM are compared

A

Lecithin-sphingomyelin ratio

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8
Q

(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

A

Lecithin

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9
Q

(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

A

Sphingomyelin

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10
Q

(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

A

F (BOTH lecithin and shingomyelin)

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11
Q

(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

A

Before 35 weeks’ gestation

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12
Q

(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

A

After 35 weeks of gestation

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13
Q

(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

A

After 35 weeks of gestation

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14
Q

(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

A

After 35 weeks of gestation

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15
Q

(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

A

preterm delivery

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16
Q

(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

A

Indicates fetal maturity

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17
Q

(5) parameters measured/detected for fetal maturity

Results encountered in fluid contaminated with blood or meconium

Lecithin-sphingomyelin ratio

A

Falsely elevated results

both these substances contain lecithin and sphingomyelin

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18
Q

(5) parameters measured/detected for fetal maturity

Quantitative measurement of lecithin and sphingomyelin is performed using?

Lecithin-sphingomyelin ratio

A

thin-layer chromatography (TLC)

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19
Q

(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)

A
  • quantitative phosphatidyl glycerol immunoassays
  • lamellar body density procedures
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20
Q

(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
A

Phosphatidyl glycerol

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21
Q

(5) parameters measured/detected for fetal maturity

respiratory distress occurs in the
presence of an L/S ratio of?

A

2.0

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22
Q

(5) parameters measured/detected for fetal maturity

must include lecithin, sphingomyelin, and PG to provide an accurate measurement of FLM.

Phosphatidyl glycerol

A

thin-layer chromatography lung profile

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23
Q

(5) parameters measured/detected for fetal maturity

has provided a more rapid and easy to perform method for assessment of fetal maturity

Phosphatidyl glycerol

A

immunologic agglutination test for PG

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24
Q

(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

A

Amniostat-FLM

25
Q

(5) parameters measured/detected for fetal maturity

sizes of agglutinates inAmniostat-FLm is read macroscopically and the results are reported as either?

Phosphatidyl glycerol

A

Negative, Low or high positive

26
Q

(5) parameters measured/detected for fetal maturity

Amniostat-FLM result

pulmonary immaturity

Phosphatidyl glycerol

A

Negative

27
Q

(5) parameters measured/detected for fetal maturity

Amniostat-FLM result

pulmonary maturity

Phosphatidyl glycerol

A

Low or high positive

28
Q

(5) parameters measured/detected for fetal maturity

T or F

Amniostat-FLM is affected by specimen contamination with blood and meconium

Phosphatidyl glycerol

A

f (Amniostat-FLM is NOT affected by specimen contamination with blood and meconium)

29
Q

(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
A

Foam stability index

30
Q

(5) parameters measured/detected for fetal maturity

(1) In foam stability index amniotic fluid is mixed with?

Foam stability index

A

95% ethanol

31
Q

(5) parameters measured/detected for fetal maturity

(2) After mixing, fluid is shaken for how many seconds?

Foam stability index

A

15 seconds

32
Q

(5) parameters measured/detected for fetal maturity

(3) After shaking, it should be allowed to?

Foam stability index

A

sit undisturbed for 15 minutes

33
Q

(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

A

continuous line of bubbles around the outside edge

34
Q

(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

A

Presence of bubbles

35
Q

(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

A

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)

36
Q

(5) parameters measured/detected for fetal maturity

Reference value for foam stability index which indicates FLM?

Foam stability index

A

value of 47 or higher
>47

37
Q

(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

A

T

38
Q

(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

A

F (cannot be used with contaminated amniotic fluid because blood and meconium also reduce surface tension, yielding a falsely mature index result)

39
Q

(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
A

Lamellar bodies

40
Q

(5) parameters measured/detected for fetal maturity

Surfactant is composed of (blank) phospholipid and (blank) protein

Lamellar bodies

percentage

A

90% phospholipid, 10% protein

41
Q

(5) parameters measured/detected for fetal maturity

Surfactant is packaged into layered storage granules called ?

A

lamellar bodies

42
Q

(5) parameters measured/detected for fetal maturity

Lamellar bodies are secreted by?

A

type II pneumocytes of the fetal
lung at about 24 weeks of gestation

absorbed into the alveolar spaces to provide surfactant

43
Q

(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

A

T

44
Q

(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

A

T

45
Q

(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

A

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

46
Q

(5) parameters measured/detected for fetal maturity

T or F

The presence of lamellar bodies decreases the OD of the amniotic fluid.

A

F (The presence of lamellar bodies increases the OD of the amniotic fluid)

47
Q

(5) parameters measured/detected for fetal maturity

Specimens are centrifuged at?

Lamellar bodies

A

2000 g for 10 minutes

48
Q

(5) parameters measured/detected for fetal maturity

Specimens are examined using wavelength of?

Lamellar bodies

A

650 nm

49
Q

(5) parameters measured/detected for fetal maturity

Reference value for lamellar body count which indicates FLM

Lamellar bodies

A

> 50,000/uL

50
Q

(5) parameters measured/detected for fetal maturity

LBC value below 15,000/μL is considered?

Lamellar bodies

A

immature

Results in between these two values are considered indeterminate and further testing using alternate methods is recommended

51
Q

(5) parameters measured/detected for fetal maturity

T or F

Lamellar body count procedure rules out interference and other contaminants such as meconium

A

F (does rule out pther interference but NOT other contaminants such as meconium)

52
Q

SUMMARY

Determine test based on refrence value and significance:

Ref. value: A450 >.025
Significance: Hemolytic disease of the newborn

A

Bilirubin scan

53
Q

Determine test based on refrence value and significance:

Ref. value: <2.0 MoM
Significance: Neural tube disorders

A

Alpha-fetoprotein

54
Q

Determine test based on refrence value and significance:

Ref. value: ≥2.0
Significance: FLM

A

Lecithin-sphingomyelin
ratio

55
Q

Determine test based on refrence value and significance:

Ref. value: Positive
Significance: FLM/PG

Fetal lung maturity/phosphatidyl glycerol

A

Amniostat fetal lung
maturity

56
Q

Determine test based on refrence value and significance:

Ref. value: ≥47
Significance: FLM

A

Foam Stability Index

57
Q

Determine test based on refrence value and significance:

Ref. value: ≥0.150
Significance: FLM

A

Optical density 650 nm

58
Q

Determine test based on refrence value and significance:

Ref. value: ≥32,000/mL
Significance: FLM

A

Lamellar body count