Amniotic Fluid Flashcards
This a colorless to Pale-yellow fluid found in the membranous sac around the fetus called as AMNION
AMNIOTIC FLUID
What are the functions of Amnionic Fluid?
FUNCTIONS:
1. Cushion for fetus
2. Allows fetal movement
3. Stabilizes temperature
4. Proper lung development
What is the normal value of Amniotic Fluid?
NORMAL VOLUME: 800 to 1,200 mL [3rd trimester]
Note:
▪ Increases throughout pregnancy
▪ Gradually decreases before delivery
What is the ultimate source of amniotic fluid water and solutes?
PLACENTA
What trimester does a 35 mL is derived from the circulation coming from the mother?
1st trimester
After the 1st trimester, the major constituent of amniotic fluid is?
FETAL URINE
The fetus already released LUNG FLUID, which may contribute to the volume of the amniotic fluid
During the 3rd trimester:
During the 3rd trimester of pregnancy, fetus release what kind of fluid? Which contributes to the volume of the amniotic fluid?
LUNG FLUID
The normal volume of the amniotic fluid is regulated by the balance of:
Production of:
Fetal urine and Lung fluid
The normal volume of the amniotic fluid is regulated by the balance of:
Absorption of Amniotic fluid by:
▪ Fetal swallowing
▪ Intramembranous flow
▪ ↑ in the normal volume of amniotic fluid
▪>1,200mL
▪ ↓ fetal swallowing of urine
▪ Neural tube defects
POLYHYDRAMNIOS
▪ ↓ in the normal volume of amniotic fluid
▪ <800mL
▪ ↑ fetal swallowing of urine
▪ Membrane leakage
▪ Urinary tract deformities*
OLIGOHYDRAMNIOS
Deformities in Urinary Tract impairs urination thus
Decreases urine output [decreased urine output also indicates decreased amniotic fluid]
What is the method collection of Amniotic Fluid?
Amniocentesis
This safe to perform among pregnant women on the 14th week of gestation [early 2nd trimester]
Amniocentesis
Amniocentesis is safe to perform among pregnant women on the what time frame?
14th week of gestation [early 2nd trimester]
The MAXIMUM VOLUME of Amniocentesis is?
30 mL
The first 2 to 3 mL is discarded because it may be contaminated with:
▪ Maternal Blood
▪ Tissue Fluid
▪ Cells
Can be assessed for Chromosomal Studies e.g. Trisomy 21 / Down Syndrome
16th week / 2nd Trimester Amniocentesis
Assessment of Fetal Lung Maturity and Fetal Hemolytic Disease
3rd Trimester Amniocentesis
The specimen must be placed on ICE during delivery
IF not performed immediately, must be refrigerated
Test for Fetal Lung Maturity (FLM)
Must the kept at room temperature or Body temperature
Test for Cytogenetic Studies / Microbial Studies
For detection of Bilirubin, a photosensitive analyte thus, it must be protected from light by using:
▪ Amber colored bottle
▪ Foil
▪ Black Plastic cover
Test for HDN
For detection of Bilirubin, a photosensitive analyte thus, it must be protected from light by using:
▪ Amber colored bottle
▪ Foil
▪ Black Plastic cover
There may be a possibility of _________ of the urinary bladder of the mother
accidental puncture
PROTEIN (+)
GLUCOSE (+)
UREA <30 mg/dL
CREATININE <3.5 mg/dL
Amniotic Fluid
PROTEIN (-)
GLUCOSE (-)
UREA >30 mg/dL
CREATININE >10 mg/dL
Maternal Urine
Why Protein and Glucose are less reliable as compared to Urea and Creatinine?
If the mother has conditions e.g. Proteinuria or Glucosuria, Maternal Urine may be False Positive (+)
Detects ruptured amniotic membranes
FERN TEST
What is specimen used in FERN TEST?
Vaginal Fluid
What are the procedures in FERN TEST?
PROCEDURE:
1. Spread on a glass slide
2. Allowed to air dry at room temperature
3. Observe under the microscope
Amniotic Fluid appears as Fern Like Crystals
Due to protein and NaCl present on Amniotic Fluid
AMNIOTIC FLUID COLOR: Colorless to Pale- Yellow
Normal
AMNIOTIC FLUID COLOR: Blood-Streaked
Traumatic tap
Abdominal Trauma
Intra-amniotic Hemorrhage
AMNIOTIC FLUID COLOR : Yellow
↑ Bilirubin [HDN]
AMNIOTIC FLUID COLOR: Dark Green
Meconium
[1st fetal bowel movement]
AMNIOTIC FLUID COLOR: Dark Red-brown
Fetal Death / Fetal Demise
What are the test in AMNIOTIC FLUID?
Test for HDN
Test for Neural Tube Defects
Test for Fetal Lung Maturity
Test for Fetal Age
Anti-D antibodies that can destroy large numbers of fetal RBCs
Results in RBC degradation product e.g. Bilirubin
HDN / ERYTHROBLASTOSIS FETALIS
a.k.a Optical density 450
Test for HDN
Absorbance of Amniotic Fluid:
▪ NORMAL: ↑365 nm, ↓550 nm
▪ HDN: ↑450 nm [maximum bilirubin absorbance]
Results on HDN TEST are plotted on a what graph?
LILEY GRAPH
Nonaffected / mildly affected fetus
Zone 1
Moderately affected fetus
▪ Close monitoring is required
Zone II
Severely affected fetus
▪ Requires intervention
Zone III
What are the interferences on HDN TEST?
INTERFERENCES:
▪ Presence of cells / meconium
▪ Presence of debris
▪ Presence of hemoglobin [410 nm peak absorbance]
Birth defect where there is incomplete closing of the backbone and membranes around the spinal cord.
SPINA BIFIDA / SPLIT SPINE
Absence of major portion of the brain and scalp
ANENCEPHALY
Major protein produced by Fetal Liver during early gestation [18th week]
Screening Test
ALPHA-FETOPROTEIN (AFP)
AFP is increased in?
Spina Bifida, Anencephaly
▪ Both Amniotic Fluid and Maternal Serum increase during pregnancy
▪ AFP will continuously increase if the skin fails to close the Neural Tissues
AFP is decreased in?
Down Syndrome
CONFIRMATORY TEST:
▪ Must not be performed if the sample is bloody
▪ Blood contains AcHE = False ↑ in Amniotic Fluid
Acetylcholinesterase (AChE)
Most frequent complication of early delivery
7th most common cause of morbidity and mortality among premature infants
RESPIRATORY DISTRESS SYNDROME
RESPIRATORY DISTRESS SYNDROME is caused by insufficient?
LUNG SURFACTANTS [Phospholipids]
Main analyte measured in Amniotic Fluid to check for Lung Maturity
It allows the alveoli to open and close during inhalation and exhalation
LUNG SURFACTANTS [Phospholipids]
TESTS FOR NEURAL TUBE DEFECTS
ALPHA-FETOPROTEIN (AFP)
TESTS FOR FETAL LUNG MATURITY
LECITHIN / SPHINGOMYELIN (L/S) RATIO
AMNIOSTAT-FLM
FOAM TEST / SHAKE TEST
MICROVISCOSITY
LAMELLAR-BODY COUNT
OD 650 nm
This the Reference Method
LECITHIN / SPHINGOMYELIN (L/S) RATIO
Primary component of Lung surfactant; A phospholipid; Low production during the 35th week and below however, after 35th week, its production increases
LECITHIN
Produced at a constant rate; Control
SPHINGOMYELIN
↓Lecithin; ↑Sphingomyelin
35th week and below
↑Lecithin; ↓Sphingomyelin
After 35th week
<35th week
<1.6 L/S Ratio
Mature fetal lungs → Preterm delivery is safe
≥2.0 L/S Ratio
Presence of Blood and Meconium
False Increase
Immunologic test for PHOSPHATIDYLGLYCEROL
The production of Phosphatidylglycerol is parallel to the production of Lecithin
Advantage: Not affected by Blood and Meconium
Disadvantage: Production is ↓ among Diabetic mothers
AMNIOSTAT-FLM
A mechanical test in assessing Fetal Lung Maturity
FOAM TEST / SHAKE TEST
Amniotic Fluid + 95% ethanol ————> stand for 15 mins
Shake for 15 seconds
Presence of Foam / Bubbles
▪ Indicates sufficient Phospholipid present in the
Amniotic Fluid
Mature Fetal Lung
A modification of Foam Test
FOAM STABILITY INDEX
0.5 increasing amount of shake for 15 secs
+ 95% ethanol ————————> Stand for 15 mins
Amniotic Fluid (0.47 - 0.55 mL)
Mature Fetal Lung:
A semi-quantitative test
Foam / Bubbles = ≥0.47 indicates MFL
Measured by Fluorescence Polarization
Surfactant-to-Albumin (S/A) Ratio is measured:
↑Phospholipid, ↓ Microviscosity
Dye Bound to Albumin: ↓Fluorescence, ↑Polarization
Dye Bound to Surfactant: ↑Fluorescence, ↓Polarization
MICROVISCOSITY
Stored form of Phospholipid in the fetus
LAMELLAR-BODY COUNT
This one is produce lung surfactants stored in the form of LAMELLAR BODIES
Type II Pneumocytes
METHODS: (LAMELLAR-BODY COUNT)
▪ Diameter of Lamellar Bodies is similar to the diameter of Platelets which is why we can use the platelet channel of Hematology analyzer
Impedance, Optical Scatter Methods
LAMELLAR-BODY COUNT
Adequate Fetal Lung Maturity:
> 32,000 /uL
↑ Lamellar Bodies = ↑ Optical Density
OD of ≥0.150 is equivalent to:
L/S Ratio: >2.0 [indicates mature fetal lung] Presence of: Phosphatidyl Glycerol
OD 650 nm
AMNIOTIC FLUID CREATININE
TEST FOR FETAL AGE
<36 weeks gestation: 1.5 to 2.0 mg/dL
36 weeks gestation: >2.0 mg/dL
AMNIOTIC FLUID CREATININE