Amniotic Fluid Flashcards
Amniotic Fluid is present in the?
Amnion
How is Amniotic fluid volume regulated?
production of fetal urine and lung fluid and absorption from fetal swallowing.
What is intramembranous flow?
Absorption of amniotic fluid water and solutes into the fetal vascular system.
Amniotic fluid increases throughout pregnancy, when does it reach its peak and how much?
1L in third trimester
What is the major contributor to amniotic fluid volume?
fetal urine
What regulates the increase in fluid volume from fetal urine?
fetal swallowing
Failure of fetus to swallow resulting in excessive accumulation of amniotic fluid is called?
What does this indicate?
- Polyhydraminos
- fetal distress
What is the ultimate source of amniotic fluid water and solutes?
Placenta
How does the composition of amniotic fluid change with fetal production of urine?
- Increase - creatinine, urea and uric acid
- Decrease - glucose and protein
Prior to 36 weeks gestation, what is the amniotic fluid cratinine range?
What happens when it rises above?
- 1.5 - 2.0 mg/dL
- >2.0 a means of determining fetal age
In amniotic fluid:
Creatinine and urea does not exceed?
How much creatining and urea is found in urine?
- Creatinine 3.5 mg/dL
- Urea 30 mg/dL
- Creatinine 10 mg/dL
- Urea 300 mg/dL
What test can differetiate amniotic fluid from urine?
What is a positive result?
- Fern test
- Fern-like crystals present in vaginal smear
How is Amniotic fluid collected?
Aminocentesis
How much amniotic fluid is drawn?
What is done with the first 2 - 3 mL?
- 30mL
- disgarded as may be contaminated with maternal blood
Aminiotic fluid specimens for cytogenetic tests should be kept at?
room temp
What test differentiates wource of blood (maternal or fetal) in amniotic fluid?
Kleihauer-Betke test for fetal hemoglobin
What produces a green color in amniotic fluid?
Merconium (newborns first poop)
A very dark brown color is associated with?
fetal death
Hemolytic Diseases of the Newborn (HDN) The destruction of fetal red blood cells and appearance of What RBC degration product?
What is measure to determin the extent of hemolysis?
- unconjugated bilirubin
- Bilirubin
Measurement of amniotic fluid bilirubin done byspectrophotometric analysis.
Optical Density (OD) of fluid is measured in intervals between?
What is th OD in normal fluid?
What is the OD when bilirubin is present?
- 365 nm - 550nm
- 365 nm and decreases to 550nm
- rise seen at 450nm
**** Absorbace difference is plotted on a Liley graph
The lily graph plot the difference in absorbance against?
How many zones afre there and what is each ones significance?
- Gestational age
- three zones
- Zone 1 mildy affected
- Zone 2 careful monitoring required
- Zone 3 severly affected, intervention throu induction of labor or intrauterine transfer
Increased levels of alpha-fetoportein (AFP) are indicative of?
Increased levels are found where and why?
- Neural tube defects
- anacephaly
- spina bifida
- maternal serum and amniotic fluid when skin fails to close over neural tissue
AFP levels are reported as?
What value is considered abnormal?
- MoM (multiples of the median)
- A value 2x the median value (>2 MoM)
Elevated AFP levels are follwed by measurement of what test?
What is it more specific for?
Amniotic acetylecholinesterase (AChE)
Neural tube disorders, not done on a bloody specimen
