amniotic fluid Flashcards
: AMNIOTIC FLUID
- Found in the
amnion
mainly delivered from the maternal
circulation which contributes approximately 35 mL of
amniotic fluid
First trimester:
mainly come from fetal urine
(major contributor of amniotic fluid volume after first
trimester)
Succeeding trimesters
(major contributor of amniotic fluid volume after first
trimester)
fetal urine
excessive accumulation of amniotic fluid
Polyhydramnios
assessment of fetal pulmonary maturity or
fetal hemolytic disease
Third Trimester
General Collection:safely performed after the __ week of
gestation
14th
decrease in amniotic fluid; caused by
increased fetal swallowing, urinary tract deformities, and
membrane leakage
Oligohydramnios
t is also associated with fetal structural anomalies,
cardiac arrythmias, congenital infections, and
chromosomal abnormalities.
Polyhydramnios:
Indicates fetal distress associated with neural tube
defects
Polyhydramnios
assessment of
genetic defects and chromosomal analysis
- Second Trimester (16th week of gestation):
Associated with congenital malformations, premature
rupture of amniotic membranes, and umbilical cord
compression that may result decelerated heart rate and
fetal death
Oligohydramnios:
: involves needle aspiration of amniotic fluid
through transabdominal amniocentesis or vaginal
amniocentesis
Amniocentesis
Maximum of__ ml using sterile syringes (discard first __
ml because it might be contaminated with maternal blood,
tissue fluid, and cells
30 mL; 2-3 mL
20
th to 42nd Weeks of Gestation
- Fetal lung maturity
- Fetal distress
- Rh HDN
- Infection
color: meconium (first defecation of the fetus)
Dark-green
increased amniotic fluid volume
Hydramnios
color: bilirubin, hemolytic disease of the newborn
Yellow:
placed on ice and refrigerate prior to
testing, refrigerated up to 72 hours prior to testing
Fetal Lung Maturity:
maintained at room or ref
temperature, to prolong the life cells to be studied
Cytogenetic studies:
must be protected from light at all times
(amber bottles)
Bilirubin analysis
separate from cells immediately using
centrifugation or filtration
Chemical testing
normal color of amniotic fluid
colorless
color: fetal death
dark red brown
color: : traumatic collection, abdominal trauma,
intra-amniotic hemorrhage
Blood-streaked
decreased amniotic fluid volume
Oligohydramnios:
amniotic fluid urea level
3.5mg/DL
amniotic fluid creatine level
30mg/dL
Maternal urine urea level
10mg/dL
maternal urine creatinine level
300 mg/dL
serves as the control or basis for lecithin
increase
Sphingomyelin:
found in the lungs, it allows the alveoli to open
for the fetus to properly inhale and exhale
Surfactant:
L:S
After 36th week of gestation:
Lecithin > Sphingomyelin
It determines the total surfactant in the lungs
Test for Fetal Lung Maturity
L/S Ratio indicates fetal lung maturity
> 2.0
Foam Stability Index : indicates fetal lung immaturity
Value of < 47
most frequent
complication of early delivery caused by the lack of
lung surfactant
Respiratory distress syndrome
Lung surfactant that may be assayed in place of L/S Ratio
- Production similar to lecithin except for diabetic mothers
(delayed)
Phosphatidylglycerol/Phosphatidylinositol
Considered as the reference method
Lecithin/Sphingomyelin Ratio
Normal L/S ratio
: 2:1
maintains alveolar stability
Lecithin:
Semiquantitative measure of the amount of surfactants
present
Foam Stability Index
L:S
Up to 26th week of gestation:
Lecithin < Sphingomyelin
L:S
36th week of gestation:
Lecithin = Sphingomyelin
Measures the change in microviscosity which decreases in
the presence of phospholipids
- Uses fluorescence polarization (Abbott TDx Analyzer) and
albumin as the internal standard
Microviscosity
L/S Ratio;; indicates fetal lung immaturity
< 1.6
Assayed using TLC or Amniostat-FLM (this uses antisera
specific for phosphatidylglycerol and is not affected by
specimen contamination with blood)
Phosphatidylglycerol/Phosphatidylinositol
Lamellar Bodies indicated fetal lung
maturity
> 32,000/m:
Shaking amniotic fluid with 95% ethanol for 15 seconds
- (+) Result: presence of bubble for 15 minutes
Foam/Shake Test
optical density of bilirubin peak
peak @ 450 nm)
Foam Stability Index; indicates fetal lung maturity
Value of ≥ 47
decreased fluorescence, high polarization
Dye-albumin
ellar Bodies
- Lamellar bodies containing surfactants and produced by
Type II pneumocytes
longer fluorescence, low polarization
- Dye-surfactant
Used for the evaluation of hemolytic disease of the
newborn caused by Rh or ABO incompatibilities
Bilirubin Analysis
Normal pregnancy: bilirubin?
decreases
bilirubin plotted on
Liley graph
Performed for the detection of neural tube defects
Alpha-fetoprotein
congenital absence of all or a major part
of the brain
Anencephaly
zone bilirubin severely affected → intervention required
(deliver/treat)
Zone 3
zone bilirubin non-affected/mildly affected → observe for
fetal stress
Zone 1
highest AFP
concentration
12th to 15th week of gestation:
AFP concentration
declines
After 15th week of gestation:
congenital cleft of the spinal column
- Produced by the fetal liver and are present in amniotic fluid
and maternal serum
Spina bifida
AFP: indicates abnormal result
MoM > 2.0: i
zone bilirubin moderately affected → requires close
monitoring and treatment
Zone 2:
Increases as the baby nears term and concentration is 1.5
to 2.0 mg/dL prior to 36th week of gestation
Creatinine Concentration
Precaution: sample should not be contaminated with blood
Acetylcholinesterase Level
Component of nerve tissue that is elevated in amniotic fluid
in neural tube defects
Acetylcholinesterase Level
Used as a confirmatory test for an elevated AFP
Acetylcholinesterase Level
Creatinine Concentration is measured by
Jaffe’s reaction
Creatinine Concentration ; indicates that the pregnancy is over 36 weeks
> 2.0 mg/dL
