Amniotic Fluid Flashcards
What functions do the amniotic fluid provide for the baby?
(1) Protection
(2) Biochemical Processes
What two anatomical units provide the formation of amniotic fluid?
Amnion and Placenta
(T/F) Amniotic fluid is similar to plasma early in the pregnancy?
True
What two main actions occur when a fetus is swallowing and urinating?
(1) Intestinal Absorption
(2) Capillary Exchange
What occurs within the amniotic fluid when the fetus swallows?
It removes electrolytes and water from the fluid.
What occurs within the amniotic fluid when the fetus urinates?
Outputs urea, creatinine, and uric acid which is exchanged with the maternal plasma in a dynamic process.
What is the procedure called for the collection of amniotic fluid?
Amniocentesis
At what age is it a requirement for a mother to receive an amniocentesis?
> = 35 years old
A pregnant mother has a chromosomal abnormality, at what age of the fetus should amniotic fluid be collected to check for fetus abnormalities?
14-18 weeks
A pregnant mother has a first child with chromosomal abnormalities, at what age of the fetus should the amniotic fluid be collected to check for chromosomal abnormalities within the fetus?
14-18 weeks
A mother finds out she is pregnant, but she has a history of a metabolic disorder, at what age of the fetus should amniotic fluid be collected to ensure no additional stress is being brought the baby?
14-18 weeks
A mother if found to have elevated maternal alpha-fetoprotein in her most recent lab work. At what age of the fetus should amniotic fluid be collected to ensure the baby isn’t receiving any addition stress? What could happen to the baby?
14-18 weeks; suspected neural tube defect
At what age of the fetus should amniotic fluid be collected to assess fetal distress due to blood group incompatibility or infection?
20-42 weeks
At what age of the fetus should amniotic fluid be collected for the assessment of fetal lung maturity?
20-42 weeks
How much fluid can be received from one amniocentesis?
15-30 mL of amniotic fluid
What type of tube should the amniotic fluid be place in?
Sterile, plastic, amber colored container
If you were to use a glass tube instead of a plastic tube?
Fetal cells can stick to glass and cause an altered result.
Why is an amber colored tube important?
Light can cause bilirubin to break down a cause a false decrease.
For cell cultures, chromosomal studies, and microbial/viral cultures, at what temperature should you place the amniotic fluid sample?
Room temperature
For fetal lung maturity testing, at what temperature should you store the amniotic fluid sample?
Refrigerated
What type of testing would require centrifugation at high speeds?
Spectrophotometric Assays (bilirubin)
What type of testing would require centrifugation at low speeds?
Recovery of fetal cells (cell cultures)
How would you differentiate between amniotic fluid and urine for glucose testing?
Amniotic fluid contains glucose; urine (usually does not)
How would you differentiate between amniotic fluid and urine for protein testing?
Amniotic fluid typically has protein (2-8 g/dL); urine (usually) contains no protein.
How would you differentiate between amniotic fluid and urine for creatinine testing?
Amniotic fluid has similar creatinine levels to plasma until ~37 weeks; urine has creatinine levels 50-100x greater than plasma.
How would you differentiate between amniotic fluid and urine for ferning testing?
Amniotic fluid has ferning persent; urine has ferning absent.
What is the normal color of amniotic fluid?
Colorless to pale yellow
What could be the cause of amber/yellow amniotic fluid?
Bilirubin
What could be the cause of green amniotic fluid?
Meconium
What could be the cause of red amniotic fluid?
Blood contamination
What is meconium?
A gelatinous/mucoid type material that is formed within the fetal intestines (baby’s first poop).
What is the turbidity of amniotic fluid early in pregnancy?
Not very turbid
What is the turbidity of amniotic fluid as pregnancy progresses?
Becomes more turbid from fetal cells, hair, vernix, etc.
What does fetal lung maturity testing help indicate?
Respiratory distress after 40 weeks.
What is the minimum age of the fetus a doctor can order FLM testing and still provide an accurate result?
After 32 weeks; before will always indicate premature lung development.
(T/F) FLM testing will produce results that will indicate a lack of surfactant.
True
What is surfactant?
(1) Alters surface tension of alveoli (expiration)
2) Reduces the amount of pressure to reopen the alveoli (inspiration
For Lecithin/Sphingomyelin (L/S) Ratio testing, what is lecithin?
Surfactant
For Lecithin/Sphingomyelin (L/S) Ratio testing, what is sphingomyelin?
Phospholipid
At what age does the Lecithin/Sphingomyelin (L/S) Ratio begin to increase?
33 weeks
In terms of Lecithin/Sphingomyelin (L/S) Ratio, what occurs between 34 and 36 weeks?
Level of lecithin ↑, sphingomyelin → or ↓
For L/S Ratio, what does a result of >2.0 indicate?
Indicates fetal lung maturity
For L/S Ratio, what does <2.0 indicate?
Indicates immature lungs
For L/S Ratio testing, how can blood affect the results?
Blood can cause a false decrease.
For L/S Ratio testing, if a sample has blood contamination, and you receive a result of <2.0, how should you proceed?
Cancel the test; cannot use result (inaccurate)
For L/S Ratio testing, if a sample has blood contamination, and you receive a result of >2.0, how should you proceed?
Okay to use result; add comment to report.
How does meconium contaminated specimens affect the L/S Ratio result?
Should not be used at all; causes a false increase.
At what age is phosphatidylglycerol (PG) detected?
35 weeks gestation
What are some advantages of phosphatidylglycerol (PG) testing?
Can be faster (TLC vs. Agglutination) and it’s not affected by blood or meconium
What are some disadvantages of phosphatidylglycerol (PG) testing?
High false negative rate
At what age is Lamellar body counts tested?
20-24 weeks
What happens to the results if there is blood contamination within a Lamellar body count?
False increased from platelets; false decreased with clot
For Lamellar body counts, what is considered mature FLM?
> 50,000/uL
For Lamellar body counts, what is considered immature FLM?
<15,000/uL
What is another name for the Foam Stability Index (FSI)?
Shake Test
What do you add to Foam Stability Index (FSI) prior to shaking?
Ethanol
What ratio are you testing during a Foam Stability Index (FSI)?
Ethanol:Amniotic Fluid Ratios
What ratio is indicative of lung maturity for the Foam Stability Index (FSI)?
> 0.47
What is a disadvantage of the Foam Stability Index (FSI)?
Meconium or bloody samples can cause a false increase.
The amount of bilirubin present is ___ related to the ___ that is happening within the fetus.
The amount of bilirubin present is directly related to the hemolysis that is happening within the fetus.
The amount of bilirubin present is ___ related to the ___ that is happening within the fetus.
The amount of bilirubin present is directly related to the hemolysis that is happening within the fetus.
What testing method is done for amniotic fluid bilirubin determination?
Spectrophotometry
How would blood affect the bilirubin result?
Oxyhemoglobin peak absorbance between 410-540nm.
How would light affect the bilirubin result?
Falsely decrease bilirubin levels (bilirubin sensitive to light)
How would meconium affect the bilirubin result?
Absorbance between 350-400 nm; falsely low result.
What does each Zone indicate?
Zone I - minimally effected
Zone II - hemolysis occurring
Zone III - severe hemolysis
If an AmniSure test is positive, what is that indicative of?
Premature rupture of membranes (PROM) has occured.
What is an advantage of AmniSure testing?
Can work with contaminated samples.
What is AmniSure testing for?
Placental alpha-microglobulin-1 (PAMG-1)
