LEC 01 - AMNIOTIC FLUID Flashcards
The fluid that bathes the fetus throughout its gestation
AMNIOTIC FLUID
_____ : produced by the amnion and the placenta from maternal plasma
Early pregnancy
____ exchange between the fetus and the surrounding medium (product of fetal metabolism)
Water-solute
UNDER COLLECTION
___ is preferred
Transabdominal amniocentesis
THREE METHODS UNDER COLLECTION
- With ultrasonic examination
- Vaginal amniocentesis
- Aspirate 10-20 ml in several sterile syringes
UNDER COLLECTION
High risk of infection and possible contamination of vaginal cells
Vaginal amniocentesis
UNDER COLLECTION
Aspirate 10-20 ml in several sterile syringes
Discard the first ___ ml
2-3
VOLUME
12 weeks gestation:
25-50 ml
VOLUME
37 weeks gestation:
800-1200 ml
Decreased fetal swallowing, congenital fetal malformations
Polyhydramnios
VOLUME
__ : < 800 ml
Oligohydramnios
Premature rupture of amniotic membrane
Oligohydramnios
VOLUME
__ : > 1200 ml
Polyhydramnios
no amniotic fluid
Anhydramnios
PHYSICAL EXAMINATION
Color
* Normal:
colorless or pale yellow
PHYSICAL EXAMINATION
Color
___ : yellow or amber
Presence of bilirubin
PHYSICAL EXAMINATION
Color
___ : green (gelatinous material that forms in fetal intestine as a result of swallowed AF and fetal intestinal secretions)
Presence of meconium
PHYSICAL EXAMINATION
Color
Fetal death:
dark red-brown
PHYSICAL EXAMINATION
Color
Blood contamination:
pale pink to red
T OR F
PHYSICAL EXAMINATION
* Early pregnancy: turbid
* Later stages of pregnancy: not very turbid
F
* Early pregnancy: not very turbid
* Later stages of pregnancy: turbid
Used to evaluate premature rupture of membranes
Fern test
Presence of ‘fern-like’ crystals on a dried vaginal fluid:
positive screen for AF
Amniotic fluid has ___ and ___ levels equal to plasma
urea AND creatinine
Creatinine comparison is challenging at ≥ __ weeks of gestation
37
CHEMICAL EXAMINATION
rarely performed test?
FETAL LUNG MATURITY TESTS
TESTS FOR FETAL DISTRESS :
GIVE ME THOSE 4 UNDER THIS
- HEMOLYTIC DISEASE OF THE NEWBORN/AMNIOTIC FLUID BILIRUBIN
- NEURAL TUBE DEFECTS
- GENETIC TESTING (e.g., trisomy 21, 18, 13; family history)
- FETAL INFECTIONS (TORCH complex)
To assess if the fetus can survive outside of the uterus in cases of anticipated premature delivery
FETAL LUNG MATURITY TESTS
A common cause of death in newborns due to insufficient surfactant production at the alveolar surfaces
Respiratory distress syndrome
SURFACTANTS
__ % phospholipids, __ % protein
90% phospholipids
10% protein
SURFACTANTS
Packaged into storage granules called ___ , secreted by type 2 pneumocytes
lamellar bodies
__ keep the alveoli from collapsing by reducing the surface tension during breathing
Surfactants
FETAL LUNG MATURITY TESTS:
GIVE ME THOSE 5 UNDER THIS
-Lecithin/sphingomyelin ratio: reference method
-Phosphatidylglycerol
-Foam stability index
-Lamellar body count
-Fluorescence polarization assay: obsolete test
THE VERY FIRST FETAL LUNG MATURITY TESTS
WHAT ARE THE pulmonary surfactants : REFERENCE METHOD
Lecithin (major) and sphingomyelin
T OR F
Lecithin/sphingomyelin ratio:
34-36 weeks: lecithin decreases; sphingomyelin remains constant or increases (produced at about 26 weeks)
F
lecithin increases; sphingomyelin remains constant or decreases
T OF F
Lecithin/sphingomyelin ratio:
< 2.0: immature lungs
> or equal to 2.0: fetal lung maturity
T
Lecithin/sphingomyelin ratio:
Measured using ___ and there should be no blood or meconium contamination
TLC
A phospholipid that enhances the spread of surfactants across the alveolar surface
Phosphatidylglycerol
Phosphatidylglycerol
Not detectable until ___ weeks gestation
35
Phosphatidylglycerol
Use TLC or agglutination slide test
___ : contains anti-PG antibodies
Reporting: negative, low positive, and high positive
Amniostat-FLM
Also known as the ‘shake test’
Foam stability index
Foam stability index
Amniotic fluid + ___ , then shake for 15 seconds= production of foam and bubbles that remain stable for 15 minutes after shaking
95% ethanol
Foam stability index
Presence of foam means ?
sufficient amount of phospholipids
Foam stability index
if the AF is contaminated with blood or meconium?
Falsely mature results
Storage of pulmonary surfactants
LAMELLAR BODY COUNT
T OR F
The number of lamellar bodies in AF correlates with the number of lecithin present in the lungs
F
phospholipids NOT LECITHIN
LAMELLAR BODY COUNT
___ : > 50,000/microliter in an uncentrifuged sample
Fetal lung maturity
Oldest routinely performed test on AF (for fetal anemia due to HDFN)
AMNIOTIC FLUID BILIRUBIN
AMNIOTIC FLUID BILIRUBIN
Measured using __
spectrophotometry
AMNIOTIC FLUID BILIRUBIN
The optical density of the fluid is measured in intervals between __ and __
350 nm AND 580 nm
AMNIOTIC FLUID BILIRUBIN
Highest OD at ___ and decreases linearly to 550 nm: normal
365 nm
Detected by measuring maternal serum alpha-fetoprotein (AFP)
NEURAL TUBE DEFECT
NEURAL TUBE DEFECT
Reported in terms of ___
multiples of the median (MoM)
NEURAL TUBE DEFECT
Elevated results are followed by measurement of
amniotic acetylcholinesterase
