Clinical Chemistry Ii Test 3 - Prenatal Testing

Front 1

How is amniotic fluid collected?

Back 1

Amniocentesis

Front 2

Amniocentesis

Back 2

Performed between 14-38 weeks, 15-30 mL collected Initial AF is an ultrafiltrate of mom’s plasma and has plasma-type values for electrolytes, urea, creatinine, etc.

Front 3

Why does amniotic fluid need to be kept from light?

Back 3

To maintain bilirubin levels

Front 4

What temperature does an amniotic fluid sample need to be kept?

Back 4

27-35 degrees for cell analysis

Front 5

What test of the amniotic fluid requires the sample to be put on ice?

Back 5

Fetal lung maturity testing because cell metabolism can change sample pH.

Front 6

What color is amniotic fluid during the first and second trimester?

Back 6

Yellowish

Front 7

What color is the amniotic fluid during the THIRD trimester?

Back 7

Colorless, turbid because of surfactant

Front 8

During maturation, the baby alters amniotic fluid. (T/F)

Back 8

True

Front 9

What analytes are increased by the baby urinating?

Back 9

Urea, uric acid, creatinine

Front 10

What analytes are increased by the baby breathing?

Back 10

Pulmonary lipids (lecithin, sphingomyelin, phosphatidylglycerol)

Front 11

What else is introduced into the amniotic fluid by the baby?

Back 11

Protein form fetal GI tract, skin, and respiratory tract
Hormones (GH, insulin, FSH, LH, ACG, ACTH, Esterdiol, T4

Front 12

What is the final volume at term?

Back 12

300 - 1500mL

Front 13

Oligohydramnios

Back 13

Low volume. Saline can be added

Front 14

Polyhydraminos

Back 14

Excessive volume

Front 15

What another name for lecithin?

Back 15

Dipalmitoyl phosphatidylcholine

Front 16

How do we test for HDN?

Back 16

Intrauterine hemolysis monitored by AF A450

Front 17

What is another name for HDN?

Back 17

Erythroblastosis fetalis

Front 18

What is HDN?

Back 18

ABO incompatability of (usually) Rh negative mother and Rh positive fetus, leading to antibody response and RBC hemolysis = bilirubin in amniotic fluid
Fetal anemia stimulates erythropoisis leading to elevated unconjugated bilirubin due to decreased conjugation by liver. Unconjugated bilirubin can cross the blood/brain barrier. Unconjugated bili (fat soluble) is toxic to CNS and causes kernicterus.

Front 19

What are the symptoms of HDN at birth?

Back 19

Anemia and kernicterus

Front 20

What are the diagnosing criteria for kernicterus?

Back 20

> 15 mg/dL tot. bilirubin
> 10 mg/dL for 2 weeks

Front 21

How do we measure bilirubin levels?

Back 21

Direct spectrophotometry. Measure bilirubin and its breakdown products from 400 to 700 nm,
draw a baseline and determine elevated absorbance at 450 nm.

Front 22

What are some interfering substances when measuring bilirubin.

Back 22

hemolysis (visible in sample and Hb peak), meconium (baby's feces), vernix (white gooey substances in AF, remove by centrifugation)

Reject hemolyzed and meconium samples

Front 23

At which zone on a Liley chart is intervention necessary?

Back 23

Zone 3. Either intraurterine transfusion or delivery (Check lung maturity first)

Front 24

What is surfactant and where is it secreted?

Back 24

Surfactant is a type of phospholipid, full of saturated fatty acids (phosphotidylcholine = lecithin, sphingomyelin, phosphotidylinositol). It is formed by type II pnemocytes and lines the alveolar epithelium.Surfactant maintains lung function by maintaining alveolar stability and reducing pressure needed to distend lungs (surface tension of alveolar wall)

Front 25

What are type I pneumocytes equipped for

Back 25

Gas exchange

Front 26

What are the components of surfactant?

Back 26

phosphotidylcholine = lecithin, sphingomyelin, phosphotidylinositol

Front 27

What is Respiratory Distress Syndrome (RDS) or hyaline membrane disease.

Back 27

Higher risk if delivery before 34 weeks.
Very small amount of lecithin and sphingomyelin
Alveoli collapse upon exhaling due to lack of surfactant
Collapse restricts gas exchange which causes respiratory acidosis and hypoxia

Front 28

What is RDS caused by?

Back 28

Respiratory distress syndrome is caused by the inability of immature lungs to produce pulmonary surfactant, the lipid conjugate that reduces surface tension in the lungs and promotes inflation of the lungs.

Front 29

What can be done to prevent RDS?

Back 29

Cortisol can be given to delay birth when preterm labor is indicated. And trigger the maturation process of the lungs when administered between 30-33 weeks of gestation AND within a week of birth.

Front 30

What is Pre-eclampsia?

Back 30

Pre-eclampsia is a condition of pregnant women marked by water retention (with swelling particularly in the feet, legs and hands), high blood pressure and protein in the urine.
Eclampsia is when pre-eclampsia progresses to a grand mal seizure

Front 31

What is a screening test for fetal lung maturity?

Back 31

Foam stability Index (FSI) or shake test

Front 32

How is the Foam stability test or shake test performed?

Back 32

Mix equal parts of amniotic fluid and methanol.
Amount of bubble correlates to the amount of surfactant in baby's lungs

Front 33

What is a L/S ratio?

Back 33

Compare the amount of lecithin (L) to the amount of sphingomyelin (S) in amniotic fluid in order to determine whether the type II pneumocytes have begun to secrete surfactant.
Sphingomyelin has no surfactant activity and is used to correct for dilutional effect of the volume of amniotic fluid

Front 34

In L/S ratio, if L/S > 2.0 and PG+

Back 34

low risk for RDS

Front 35

In L/S ratio, if L/S > 2.0 or PG+ (not both)

Back 35

Medium risk for RDS

Front 36

In L/S ratio, if L/S < 2.0 and PG-

Back 36

high risk for RDS (delivery should be delayed if possible)

Front 37

Diabetic mothers need > 2.5 and PG+ to be considered low risk. (T/F)

Back 37

True

Front 38

What is PG

Back 38

Qualitative immunoassay
> 2 mg/L indicates low risk for RDS
Not a ratio, therefore does not correct for large or small volume of AF

Front 39

What is Amniotic surfactant to Albumin ratio or Fetal lung maturity test (FLMT)?

Back 39

The assay is performed on a special fluorescence polarization instrument
"Mature fetal lungs" are indicated by values greater than 50 mg surfactant per gram of albumin

Front 40

What are lamellar bodies?

Back 40

Lamellar bodies are the storage form of surfactant and are similar in size to normal platelets.

Front 41

How is a Lamellar Body Count performed?

Back 41

They can be counted on a automated cell counter
A count of these bodies estimates the amount of surfactant present
A lamellar body count >30,000/μl is highly predictive of pulmonary maturity, while a count <10,000/μl suggests a risk for Respiratory Distress Syndrome
Lamellar body count methods are faster and less technique dependent than traditional phospholipids analysis

Front 42

What technique is used to measure bilirubin levels in amniotic fluid?

Back 42

Spectophotometry

Front 43

What technique is used to measure the surfactant to albumin ratio?

Back 43

Fluorescence polarization

Front 44

What technique is used to measure the L:S ratio?

Back 44

Chromatography

Front 45

Neural tube forms ____________ and _____________ during development

Back 45

brain and spinal cord

Front 46

What is spina bifida?

Back 46

A condition where the neural tubes do not close (tissue does not cover spinal cord) and the baby's spinal fluid seeps into AF and AF gets absorbed into mom's plasma

Front 47

What is encephalocele?

Back 47

a protrusion of brain through an abnormal opening

Front 48

What is anencepha?

Back 48

a condition in which the fetus does not develop a cerebrum

Front 49

What does the baby's liver make In all the neural tube defects instead of albumin longer than it should?

Back 49

Alpha fetal protein measured in mom's plasma by immunoassay. Increase result is preliminary indicator of open neural tube defect, must be followed by ultrasound and AFAFP. Ultrasound because AFP can be increased with multiple pregnancies.

Front 50

What is the most significant protein that is found in the second trimester fetus?

Back 50

AFP

Front 51

What is AFP and where is it produced?

Back 51

a transport protein produced by the fetal liver with a function similar to that of albumin

Front 52

What does AFP bind and transport?

Back 52

binds and transports substances that are not very water soluble such as steroid hormones, vitamins, lipids and bilirubin

Front 53

Where is AFP found?

Back 53

found in amniotic fluid and maternal circulation only in small amounts under normal circumstances due to its large molecular weight and inability to diffuse readily to maternal circulation from the feto-placental circulation

Front 54

In what conditions is AFP elevated?

Back 54

OPEN NEURAL TUBE DEFECTS, Trisomy 13, twins or other multiple gestations, underestimated gestational age

Front 55

In what conditions is AFP decreased?

Back 55

DOWN'S SYNDROM, Trisomy 18

Front 56

When is AFAFP measured?

Back 56

Between 15 and 21 weeks of pregnancy
<15th week – too little to accurately measure
>21st week– normal range is too wide to detect accurately

Front 57

How are the results reported in an AFP?

Back 57

Results reported in MOM (multiples of median = how many times normal)
Normal is <2.0 MOM unit

Front 58

AFAFP is increased in ________% of ONTD cases.

Back 58

90%

Front 59

Folic acid can reduce the risk of ONTD. (T/F)

Back 59

True

Front 60

How do you calculate MoM units?

Back 60

Serum AFP / avg. of fetus' at that gestational age
If elevated, quad screen can be performed

Front 61

What is Downs syndrome?

Back 61

Down syndrome is a congenital disorder of the autosomal chromosome 21 with either a trisomy or three copies of the long arm, or translocations of the long arm

Front 62

What are the lab markers for Down's syndrome?

Back 62

decreased MSAFP, decreased unconjugated estriol and increased chorionic gonadotropin levels. (Triple Screen) Add inhibin becomes quad screen.

Front 63

What is the definitive tst for Down's syndrome?

Back 63

fetal karyotyping

Front 64

What is Trisomy 18?

Back 64

Trisomy 18, an extra copy of chromosome 18, results in open neural tube defects, and death of the infant within a few months.

Front 65

What screen is used to determine whether or not the patient has trisomy 18?

Back 65

The triple screen of maternal serum provides the same type of abnormal results as does Down’s syndrome while fetal karyotyping is the definitive test and will differentiate trisomy 21 from 18

Front 66

Multiple pregnancies (twins) can result in nearly double the amount of alpha fetoprotein found in maternal circulation. (T/F)

Back 66

True

Front 67

Multiples of median (MoM) is a statistical application of the biochemical marker used to normalize values for reference ranges that change readily with age or other factors. (T/F)

Back 67

True

Front 68

What is the fetal fibronectin test?

Back 68

Test used to predict imminent delivery within the next few weeks. Fibronectin is a glue like protein used to hold baby in womb. protein breakdown before labor and release in uterus. indicative of imminent delivery (within 2 weeks)

Front 69

(TPQ) Decreased maternal AFP and increased hCG suggest high risk for what clinical condition?

Back 69

Down's syndrome

Front 70

(TPQ) what is the unit for AFP?

Back 70

MoM