Amniotic Fluid Flashcards
Amniotic fluid is Found around the developing fetus inside a membranous sac called
Amnion
Main function of amniotic fluid
- cushion and protect the developing fetus
- serves a key role in the exchange of water and molecules between the fetus and the maternal circulation
Amniotic fluid is formed from the
Placenta
Volume of amniotic fluid increases steadily throughout the pregnancy up to a maximum of
1100-1500 mL at 36 weeks of gestation.
When fetal urine production begins, the chemical composition of the amniotic fluid changes
Increased production creatinine
At commencement of fetal urine production, fetal swallowing of amniotic fluid begins and this regulates the formation of
fetal urine.
Decreased fetal swallowing resulting in increase amniotic fluid volume
HYDRAMNIOS:
Decreased amounts of amniotic fluid. Can occur with premature rupture of the membranes and Congenital malformations
OLIGOHYDRAMNIOS:
amniotic fluid volume greater than 1200 mL is
Polyhydramnios
excessive accumulation of amniotic fluid, amniotic fluid volume greater than 1200 mL is
Polyhydramnios
collection of amniotic fluid
AMNIOCENTESIS
Amniocentesis can be collected either by
Transabdominal or transvaginal
Needle aspiration is introduced into the amniotic sac, usually transabdominally with simultaneous use of
Ultrasound
The addition of ultrasound has helped to make the procedure safer especially if performed between
15 - 18 weeks of gestation for genetic studies
Amount of amniotic fluid collected is usually
10-20 mL (max of 30)
less desirable as cells have more tendency to adhere to its surface
Glass containers
Color of normal amniotic fluid
Colorless to pale yellow
Amniotic fluid is slightly turbid due to
Fetal cells, vernix, hair
(protective coating that forms on baby’s skin in utero)
Vernix
Specimen for Cell Culture and Chromosomal Studies
- stored at Room temperature
- to keep the fetal cells alive
Specimen for phospholipid analysis
transported on ice and centrifuged at 500 g and the supernatant saved for testing.
if blood is present in specimen for phospholipid analysis
specimen should be centrifuged to prevent hemolysis from altering the test results
Specimen for chemical analysis
Stored at any length of time but must be centrifuged.
If samples for chemical analysis need to be stored more
24 hours, they must be
Frozen
Microscopic test to differentiate amniotic fluid from maternal urine.
Fern test
In fern test - is spread out on a glass slide and allowed to dry at room temperature.
Vaginal fluid
It is a test used to evaluate pre-mature rupture of the membranes.
Fern test
Colorless amniotic fluid may indicate
Normal (MAY SHOW SLIGHT TO MODERATE TURBIDITY)
BLOOD STREAKED
TRAUMATIC TAP, ABDOMINAL TRAUMA, INTRA AMNIOTIC HEMORRHAGE
YELLOW
HEMOLYTIC DISEASE OF THE NEWBORN
DARK GREEN
MECONIUM
DARK RED BROWN
FETAL DEATH
L/S RATIO (Lecithin/Sphingomyelin) principle
Thin Layer Chromatography
Amniostat FLM principle
Agglutination immunoassay
L/S RATIO (Lecithin/Sphingomyelin) details
Sphingomyelin is used as internal standard,
Amniostat FLM details
Uses antisera specific to phosphatidylglycerol.
greatly affected by blood and meconium contamination
L/S RATIO (Lecithin/Sphingomyelin)
Not affected by blood and meconium contamination
Amniostat FLM
L/S RATIO (Lecithin/Sphingomyelin) NORMAL VALUES:
> 2.0
NORMAL VALUES: of amniostat FLM
Positive
FOAM STABILITY INDEX principle
Modified Foam shake
FOAM STABILITY INDEX details
95% ethanol used as anti-foaming agent
Normal values of foam stability index
> 47
MICROVISCOSITY principle
Fluorescence polarization
MICROVISCOSITY normal values
> 55 mg/g
MICROVISCOSITY details
Albumin used as internal standard
LAMELLAR BODY COUNT principle
Resistance pulse counting
LAMELLAR BODY COUNT details
Uses the platelet channel of hematology analyzers
LAMELLAR BODY COUNT normal values
> 32,000/mL
