Amniotic Fluid

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What is the normal gestation period?

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Which of the following is a function of amniotic fluid?

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Initially, amniotic fluid is produced by the .

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Production of amniotic fluid in the first trimester is supplied by , approximately .

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Amniotic fluid in the first trimester is similar to the composition of the mother's plasma (plus some sloughed off cells from the fetus).

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In the 2nd trimester, is the main contributor.

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In the last half (to 1/3) of the pregnancy, regulation of the volume of amniotic fluid is
further influenced by the production of .

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Surfactants secreted by the fetus include

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The volume of amniotic fluid increases throughout the pregnancy and peaks during the (around 36 weeks gestation) before gradually prior to delivery.

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_______ is an excess accumulation of amniotic fluid due to failure of the fetus to
start swallowing the fluid.

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Polyhydramnios is associated with _ while oligohydramnios is associated with __.

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Check the answers that are associated with polyhydramnios.

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Check the answers associated with Oligohydramnios.

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As the pregnancy continues, the composition of amniotic fluid changes to reflect contributions from the fetus. Check the answers to the changes that we would see in this case.

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Amniotic fluid creatinine levels may be used to assess fetal age. At less than 36 weeks old, that should be mg/dL. At greater than 36 weeks old, that should be .

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Generally, amniocentesis can be performed anytime after 8 weeks gestation, but the purpose for
the procedure dictates when it is actually performed.

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Amniocentesis when used to screen for birth defects is performed between weeks.

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Amniocentesis, when performed to monitor fetal distress is performed between weeks.

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Check the appropriate boxes associated with amniotic fluid collection.

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is recommended for FLM (fetal lung maturity studies) to prevent loss of phospholipids (lung surfactants)

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Surfactants are unstable at room temperature but stable if refrigerated for up to 72 hours

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Centrifugation must be done much slower than for other specimen types. 140g are used to recover
fetal cells, 500g is used to separate supernatant containing phospholipids for FLM analysis. Higher
centrifugation forces will result in loss of phospholipids into the pellet with erroneous L/S ratio
(later). Other assays can be done in clear supernatant after centrifugation at 1500g (5 to 15
minutes).

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The mother's triple screen serum test includes , , and .

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Produced by the fetal liver during 1st trimester; elevated with open neural tube defects (such as spina bifida – neural tissue is exposed, not covered with skin) – elevated in amniotic fluid and also in the mother’s circulation. Low levels are associated with Down Syndrome.

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Low levels are a concern for maintaining the pregnancy. High levels are associated with down syndrome.

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High "unconjugated estriol" indicates a problem with the fetus development.

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Erroneous results can be obtained for ____ due to preeclampsia, anemia, and kidney disease.

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DHEA, a precursor hormone, is produced by the fetal adrenal glands and converted to estriol in the placenta.

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What is included in a Quad Screen?

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Inhibin-A is a protein produced by the fetus and ovaries. Elevated values, together with increased hCG, decreased AFP and estriol, are a better indication of Down syndrome.

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The fern test helps determined if there is premature rupture of the amniotic sac. Vaginal fluid is smeared on a glass slide and allowed to dry. If amniotic fluid is present, it will crystalize in a characteristic fern-like formation.

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All amniotic fluid is turbid to some degree

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A protein produced by the fetal liver during the 1st trimester and present in both fetal serum and fetal CSF

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These are tests that measure the various lung surfactants - lecithin, sphingomyelin, and .

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The Foam Stability Index (FSI) is a test that measures the relative amounts of ; it
correlates well with results of the L/S ratio and phosphatidyl glycerol assays.

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AFP Levels peak at 16 weeks (500µg/L) then slowly decrease. Only a small (<1%) amount is filtered by the kidney and excreted in fetal urine. As a result, small amounts of AFP are normally present (< 10 µg/L) in amniotic fluid.

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Check the tests associated with assessing AFP levels.

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AChE acetylcholinesterase is normally present in amniotic fluid (called pseudoacetylcholinesterase) and it will
migrate slow in electrophoresis. With open NTDs, another form specific to neural tissue will be present that
migrates much faster.

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Amniotic fluid - Bilirubin and the Liley Graph - Zone 1

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Amniotic fluid - Bilirubin and the Liley Graph - Zone 3

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FML maturity - baby is mature enough to avoid respiratory distress syndrome and
delivery will be induced. After how many weeks is this usually? Answer: After weeks

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When results of the Liley graph point to very early induction, fetal lung maturity must first
be assessed. This is done by testing the level of present in the amniotic
fluid.

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The most common complication of early delivery and is the leading cause of death in premature infants.

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The function of the surfactant is to keep the .

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The primary lung surfactant is

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production increases toward the end of the pregnancy; by 34-36 weeks the
amount of is present in sufficient amounts to prevent alveolar collapse.

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is a lipid that is produced at a constant steady rate after 26 weeks. The
exact role of has not yet been determined but is used as a reference for
lecithin.

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Prior to 35 weeks L/S is usually <, but as lecithin increases (and sphingomyelin
remains constant) the ratio increases. When it reaches it is considered safe to
deliver the baby.

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Lecithin and sphingomyelin are measured by

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parallels the production of lecithin except in cases of maternal diabetes where production is delayed. In this case RDS can occur with an L/S of 2.0.

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It is best to have an L/S ratio > 2.0 and detectable PGL to ensure FLM, however it’s only necessary
in women with gestational diabetes to measure all three.

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uses antisera specific for phosphatidyl glycerol; this is a semi-quantitative
agglutination slide test that is faster to perform than TLC. There is no interference by blood
or meconium but it has higher incidence of false negatives

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Phosphatidyl glycerol (PGL) is measured by (check all associated with it).

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Rapid tests for determining FLM (Check all that apply).

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The FSI is based on the fact that destroys ; it is an antifoaming agent.

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Amniotic Fluid - FSI

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Foam Stability Test - The presence of bubbles around the outside edge of the
liquid surface is a sign that a sufficient amount of these phospholipids are present to
support lung function. This test may be performed at the bedside by the physician.

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FSI: The ones with less ethanol should have less bubbles because ethanol is an antifoaming agent.

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The first tube that shows foaming gives us the FSI.

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FSI: If it corresponds to 47 or higher (0.47 mL ethanol or greater) that means there are enough phospholipids to over come the antifoaming action of the ethanol even at that higher amount and thus the lungs are mature enough.

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The storage form of lung surfactants

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As the lungs mature the increased lamellar body production reflects a decrease in phospholipids and L/S ratio.

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will increase the optical density of amniotic fluid.

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When measured at 650 nm, falsely increases the optical density, but does not.

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An OD reading of 0.150 correlates well with an L/S ratio ≥ 2.0 and the presence of phosphatidyl glycerol.

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In a lamellar body count, contamination from will falsely increase the counts since will be present.

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is a glycoprotein secreted during pregnancy by cells of the fetal membranes (amnion and chorion) that make the amniotic sac and the fetal side of the placenta. It acts as a glue that binds the placenta to the uterus.

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During weeks 22 to 35, the presence of may be used as a predictor for preterm delivery.
If detected, it might be necessary for the mother to be on bed rest for the remainder of the pregnancy. A negative test is a predictor that delivery over the next two weeks is unlikely

From the amniotic fluid lecture

Amniotic Fluid

What is the normal gestation period?

Which of the following is a function of amniotic fluid?

Initially, amniotic fluid is produced by the .

Production of amniotic fluid in the first trimester is supplied by , approximately .

Amniotic fluid in the first trimester is similar to the composition of the mother's plasma (plus some sloughed off cells from the fetus).

In the 2nd trimester, is the main contributor.

In the last half (to 1/3) of the pregnancy, regulation of the volume of amniotic fluid is further influenced by the production of .

Surfactants secreted by the fetus include

The volume of amniotic fluid increases throughout the pregnancy and peaks during the (around 36 weeks gestation) before gradually prior to delivery.

_______ is an excess accumulation of amniotic fluid due to failure of the fetus to start swallowing the fluid.

Polyhydramnios is associated with _____ while oligohydramnios is associated with ______.

Check the answers that are associated with polyhydramnios.

Check the answers associated with Oligohydramnios.

As the pregnancy continues, the composition of amniotic fluid changes to reflect contributions from the fetus. Check the answers to the changes that we would see in this case.

Amniotic fluid creatinine levels may be used to assess fetal age. At less than 36 weeks old, that should be mg/dL. At greater than 36 weeks old, that should be .

Generally, amniocentesis can be performed anytime after 8 weeks gestation, but the purpose for the procedure dictates when it is actually performed.

Amniocentesis when used to screen for birth defects is performed between weeks.

Amniocentesis, when performed to monitor fetal distress is performed between weeks.

Check the appropriate boxes associated with amniotic fluid collection.

In the last half (to 1/3) of the pregnancy, regulation of the volume of amniotic fluid is
further influenced by the production of .

_______ is an excess accumulation of amniotic fluid due to failure of the fetus to
start swallowing the fluid.

Polyhydramnios is associated with _ while oligohydramnios is associated with __.

Generally, amniocentesis can be performed anytime after 8 weeks gestation, but the purpose for
the procedure dictates when it is actually performed.

The Foam Stability Index (FSI) is a test that measures the relative amounts of ; it
correlates well with results of the L/S ratio and phosphatidyl glycerol assays.