Study guide Chapter 10 - OB

List risks of midtrimester amniocentesis.

Pregnancy loss, fetal hemorrhage if the placenta or cord is pierced, Rh sensitization.

List risk of CVS.

Pregnancy loss, infection, limb reduction defects. Rh sensitization, expense, unexpected need for added tests.

List typical purposes for an ultrasound examination during the first trimester.

Confirm pregnancy and its location, gestational age, whether pregnancy is multifetal; confirm fetal viability; adjunct to chorionic villus sampling; identify fetal markers that suggest major anomalies.

What is the purpose of Phosphatidylglycerol (PG) and phosphatifylnositol (PI) test from the amniotic fluid? What may alter amniotic fluid tests for fetal lung maturity?

Presence in the amniotic fluid confirms fetal lung maturity. Test may be affected by the presence of blood or meconium in the fluid.

lecithin/sphingomyelin ratio (L/S ratio)

Ratio of two phospholipids in amniotic fluid used to determine fetal lung maturity; ratio of 2:1 or greater usually indicates fetal lung maturity.

What lecithin/sphinomyelin (L/S) ratio suggests that the fetal lungs are mature? In what maternal disorder may this ratio not be associated with fetal lung maturity?

Ration of 2:1; diabetes mellitus

Fewer fetal movements than expected suggest possible..

Reduced placental perfusion with fetal hypoxia.

What is the correct client teaching to follow amniocentesis?

Report persistent contractions, vaginal bleeding, fluid leaking, or fever.

You are observing for fetal heart rate (FHR) accelerations in a nonstress test (NST) for a woman who is 26 weeks pregnant. The average FHR baseline is 145 to 155 beats per minute (BPM). Within 20 minutes, the FHR accelerated to 165 six times for 10 to 15 seconds. How should you interpret this information?

Results are reassuring because the FHR accelerated 10 bpm for 10 seconds.

List purposes for amniocentesis during the second trimester (midtrimester).

-Maternal age is greater than or equal to 35. -Chromosomal abnormally in close family member. -Gender determination for maternal carrier of X-linked disorder (such as hemophilia, Duchenne's muscular dystrophy). -Birth of previous infant with chromosomal abnormalities or an open neural tube or body wall defect. -Pregnancy after three or more spontaneous abortions. -Elevated levels of maternal serum alpha-fetoprotein or multiple-marker screen that remain unexplained. -Maternal Rh sensitization of materna Rh-negative blood to fetal Rh-positive blood.

Describe possible results and implications of a contraction stress test.

1. Negative (reassuring) - no late decelerations (decrease in the FHR that persist after the contraction ends) occurred in the FHR, although the fetus was stressed by three contractions of at least 40 seconds duration in a 10-minute period. 2. Positive (abnormal) - 50% or more of contractions are accompanied by late decelerations, even if there are fewer than three contraction in 10 minutes. 3. Equivocal (suspicious) - intermittent late FHR decelerations and significant variable decelerations. 4. Equivocal (tachysystole) _ FHR decelerations that occur in the presence of contractions that are closer than every 2 minutes or last longer than 90 seconds. 5. Unsatisfactory - fewer than three contractions in 10 minutes or any tracing that cannot be interpreted.

Chorionic villus sampling (CVS) is done between ______ and _____ weeks of pregancy. Results are usually available in what length of time?

10;12; preliminary results in 2 to 3 hours; 2 to 4 days for improved quality of test results; 7 days for tissue culture analysis; varying time of results for tests othee than karyotyping.

karyotype

A display of the chromosome pairs of a cell arranged by size and shape.

What is the appropriate client teaching related to maternal serum Alpha-fetoprotein (MSAFP) analysis?

Abnormal MSAFP levels should be followed by more specific test.

What risk are involved with percutuneous unbilical blood sampling (PUBS).

Bradycardia, prolonged bleeding, cord laceration, cord hematoma, thrombosis, and thromboembolism, preterm labor, preterm rupture of membranes, maternal blood sensitization.

What two methods are used to cause uterine contractions in a contraction stress test?

Breast self-stimulation, oxytocin infusion.

What is the purpose of TDx assay test from the amniotic fluid? What may alter amniotic fluid tests for fetal lung maturity?

Determines surfactant content in amniotic fluid. Test may be affected by the presence of blood or meconium in the fluid.

Oligohydramnios

Less amniotic fluid than normal

List indications for performing percutuneous unbilical blood sampling (PUBS).

Management of Rh disease; genetic studies; diagnosis of abnormal fetal blood clotting factors; treatment of fetal blood diseases or delivery of therapeutic drugs that cannot be delivered to the fetus in another way.

hydramnios

More amniotic fluid than normal.

What is multiple-maker screening, and what is it purpose? What follow-up test may be needed?

Multiple-marker screening includes maternal serum alph-fetoprotein, human chorionic gonadotropin, unconjugated estrilos, and sometime inhibinn A. Screening increases detection of trisomies, such as trisomy 18 and trisomy 21. Follow-up for abnormal levels may include amniocentesis with karyotyping.

What conditions are suggested by alpha-fetoprotein levels that are high?

Open neural tube defects (anencephaly, spina bifida). Esophageal obstruction. Abdominal wall defect (omphlocele, gastroschisis) Increased amount leaked by fetal kidney (hydronephrosis) Threated abortion. Fetal demise. Normal fetus in conjunction with one or more of the following: Amniotic fluid contaminated with fetal blood (during amniocentesis, percutaneous umbilical blood sampling. Underestimation of fetal age. Maternal insulin-dependent diabetes (such as type I) Incorrect maternal weight (lower than the true weight) Multifetal gestation.

The fetal heartbeat should be visible on ultrasound by the ....

Sixth week following the last menstrual period.

baseline risk

The risk, usually in reference to birth defects or spontaneous abortion, of the general population of pregnant women who have no identified high-risk factors or invasive procedures.

late deceleration

The slowing of the fetal heart rate after the onset of a uterine contraction and persisting after the contraction ends.

Mid trimester amniocentesis results for genetic studies are known in approximately what length of time?

Three to seven days for chromosome analysis, depending on the test. More rapid results may include analysis using DNA probes, fluorescent probes (fluorescent in-situ hybridization (FISH). or spectral karyotyping. Time required to test for specific disorders varies.

In which type of ultrasound examination, transvaginal or transabdominal, is a full bladder often needed? What is the reason? What effect may this have on the woman?

Tranabdominal. Elevates the uterus and displaces the gas-filled intestine if needed. Discomfort in bladder area when scanned.

vibroacoustic stimulation

Use of sound stimulation to elicit fetal movement and acceleration (speeding up) of the fetal heart rate.

What is the purpose of a vibroacoustic stimulation test (VAS)?

VAS identifies whether fetal heart rate (FHR) accelerations occur in response to sound stimulation' it shortens nonstress test (NST) or confirms a nonreactive NDT. VAS can be used in the intrapartum period to clarify questionable problems.

bilirubin

Waste product of eryghrocyte (red blood cells) breakdown.

meningocele

a congenital anomaly of the central nervous system in which a sac protruding from the brain or the spinal meninges contains cerebrospinal fluid (but no nerve tissue)

neural tube defect

a congenital defect in closure of the bony encasement of the spinal cord or skull. includes defects such as anencephaly, spina bifida, meningocele, myelomeningocele and others

placenta previa

abnormally low implantation of the placenta on the uterine wall

anencephaly

defect in closure of the cephalic portion of the neural tube that results in incomplete development of the brain and bones of the skull; the most drastic neural tube defect usually results in a stillbirth

inhibin A

hormone produced by placenta levels of HCG & inhibin A are higher when a woman has increased risk of fetal Down syndrome lower than normal levels can also indicate Down syndrome risk

contraction stress test

method for evaluating fetal status during the antepartum period by observing the response of the fetal heart to intermittent stress of uterine contractions.

chorionic

pertaining to the outermost layer of the two membranes surrounding the embryo; it forms the fetal part of the placenta

Alpha-fetoprotein (AFI)

plasma protein produced by the fetus.

estriols

protein from placenta and fetal liver

cordocentesis

sampling of fetal blood drawn from the umbilical vein and preformed under ultrasound guidance

Chorionic villus sampling

sampling of placental tissue for microscopic and chemical examination to detect fetal abnormalities

human chorionic gonadotropin

stimulates the corpus luteum to grow and secrete estrogen and progesterone at a higher rate; pregnancy tests work by detecting this in women's urine

nonstress test

this test determines the fetal well-being, measured by the ability of the fetus to respond to its bodymovement by accelerations of the heart rate.

What conditions are suggested by alpha-fetoprotein levels that are low?

Chromosomial trisorries (e.g. Down syndrome, or trisomy 21). gestational trophoblactic disease. Normal fetus in conjunction with: Overestimation of gestaion age Increased maternal weight (higher than true weight)

List purposes for amniocentesis during the third trimester.

Evaluate fetal lung maturity, identify fetal hemolytic disease.

What is the significance of oligohydramnios?

During fetal hypoxemia, blood is shunted away from the kidneys and lungs and toward the brain, resulting in a lower amniotic fluid volume. It may indicate chronic fetal hypoxia.

The biophysical profile assesses which fetal parameters?

FHR activity as in the NST. Fetal breathing movements. Gross fetal movements. Fetal tone. Amniotic fluid volume.

The basic principle of the contraction stress text is to observe the response of the ______ to the stress of ______.

FHR; uterine contractions.

A woman who is assessing fetal movements each day should notify her health care provider if...

Fetal movements are fewer than the minimum set by the provider.

Ultrasonography

Imaging technique that uses high-frequency sound waves to visualize internal body structures.

uteroplacental insufficiency

Inability of the placenta to exchange oxygen, carbon dioxide, nutrients, and waste products properly between the maternal and fetal circulations.

percutaneous umbilical blood sampling (PUBS)

Insertion of a needle directly into a fetal umbilical vessel under ultrasound guidance; two potential complications: fetal hemorrhage and risk of infection. Used for prenatal diagnosis of inherited blood disorders such as hemophilia A, karyotyping, detection of fetal infection, determination of acid-base status and assessment and treatment of isoimmunization. Generally performed after 16 weeks' gestation.

biophysical profile (BPP)

A biophysical profile is a prenatal ultrasound evaluation of fetal wellbeing, involving a scoring system. It is often done when a non-stress test is non reactive, or for other obstetrical indications. this assessment evaluates: fetal breathing movements, gross body movements, fetal tone, reactive fetal heart rate, qualitative amniotic fluid volume. each component is scored as 2 or 0. a "good" score is a 10, and 6 - 8 is ok as long as amniotic fluid scores a 2.

phosphatidylglycerol (PG)

A major phospholipid component of surfactant; presence in amniotic fluid indicates fetal lung maturity

phosphatidylinositol (PI)

A phospholipid component of surfactant that is produced and secreted in increasing amounts as fetal lungs mature

Amniocentesis

A technique of prenatal diagnosis in which amniotic fluid, obtained by aspiration from a needle inserted into the uterus, is analyzed to detect certain genetic and congenital defects in the fetus.

Under what circimstances is an accurate gestational age especially important? How is it assessed by ultrasonography? When is the gestational age determination most accurate?

Accurate gestational age is needed for best maternal serum alpha-fetoprotein evaluation, to identify intrauterine growth restriction or if there is a question about the expected date of birth. It is most accurately assessed during the first trimester by measuring the crown-rump length. During the last half of pregnancy, gestational age is assessed by several measurements including the biparietal diameter, femur length, and abdominal circumference. From 24 to 32 weeks of gestation, two or three serial ultrasound measures taken 2 weeks apart can better establish gestational age when they are compared with standard fetal growth curves.

multiple-marker screening

Analysis of maternal serum for abnormal levels of alpha-fetoprotein, human chorionic gonadotropin, and estriols that may predict chromosomal abnormalities of the fetus; often called triple-screen. Addition of tests such as inhibin A has improved accuracy of the results, leading to alternate names for this package of tests.

surfactant

Combination of lipoproteins produced by the lungs of the mature fetus to reduce surface tension in the alveoli, this promoting lung expansion after birth.

List typical purposes for an ultrasound examination during the second and third trimester.

Confirm fetal viability, gestational age and growth; locate placenta; determine fetal presentation and anatomy; evaluate amniotic fluid volume and fetal movement; adjust to amniocentesis and percutanious umbilical blood sampling; evaluate umbilical cord.

myelomeningocele

a congenital defect of the central nervous system in which a sac containing part of the spinal cord and its meninges protrude through a gap in the vertebral column

spina bifida

a congenital defect that occurs during early pregnancy when the spinal canal fails to close completely around the spinal cord to protect it

ultrasound

a procedure that uses high-frequency sound waves to determine the size and position of a developing fetus

delta OD 450

a test used to measure the change in optical density of the amniotic fluid caused by staining with bilirubin