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97 Cards in this Set
- Front
- Back
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what is A optional process that involves information gathering, risk assessment, diagnosis and education for the benefit of the patient, her family and her unborn child?
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prenatal testing
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how many yrs has prenatal testing been in effect?
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40 yrs
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what are the goals of prenatal testing?
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To provide a way to identify pregnancies at risk
To provide a range of informed choices to the couple at risk for having a child with an abnormality To provide reassurance and to reduce anxiety, especially among high-risk groups To allow couples at risk for having a child with a specific birth defect to begin a pregnancy with the knowledge that the disorder could be confirmed by testing To allow couples the option of appropriate management for the impending birth of a child with a genetic disorder To allow timely diagnosis of affected fetus to permit termination of the pregnancy To enable prenatal treatment of affected fetus |
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what are the basics of prenatal testing?
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Non-invasive means of prenatal diagnosis used as primary screening
Available to ALL pregnant women Optional |
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what are the methods of the primary prenatal diagnosis?
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Routine prenatal history and physical
First trimester maternal serum screening and ultrasound Second trimester maternal serum screening and ultrasound |
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what is maternal serum screening?
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Noninvasive
Voluntary Not diagnostic |
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what's the goal of maternal serum screening?
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Goal: to identify patients at increased risk of a fetal disorder for the purpose of offering secondary prenatal diagnosis
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when is this screened for?
Open Neural Tube Defects Fetal Down’s Syndrome |
primary maternal serum screening
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when is this screened for?
Other chromosomal abnormalities Open abdominal wall defects |
secondary maternal serum screening
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when are these tests done?
Serum PAPP-A, Human Chorionic Gonadotrophin (Beta HCG) |
1st trimester (maternal serum screening)
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when are these tests done?
Triple Marker Screen (MSAFP, Beta HCG, estriol) Quadruple Marker Screen (add Inhibin) |
second trimester: maternal serum screening
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what is Fetal glycoprotein produced mainly in the liver?
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alpha-fetoprotein
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what path does alpha-fetoprotein take in body?
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Secreted into the fetal blood stream, and excreted through fetal kidneys into amniotic fluid
Also enters the maternal blood stream via placenta and can be assayed |
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what is alpha fetoprotein associated w/ ?
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Associated with open neural tube defects and abdominal wall defects
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when is this screened for?
Pregnancy location Multiples Viability Nuchal translucency |
ultrasound screening: 1st trimester
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when is this screened for?
Anatomic screen Placentation Umbilical Cord Amniotic Fluid |
ultrasound: second trimester
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when do you see this:
Markedly increased risk of chromosomal abnormalities Increased risk for miscarriage and perinatal death Increased incidence of cardiac defects, diaphragmatic hernia and other birth defects Increased incidence of genetic syndromes |
First Trimester Ultrasound Screening: Increased Nuchal Translucency
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when/how is this done?
Detection of fetal sex from 15 weeks gestation onward Evaluation of multiple organ systems Evaluates location and character of placenta Evaluates quantity and distribution of amniotic fluid |
Second Trimester Ultrasound Screening
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what are you looking for in Second Trimester Screening Ultrasound: Organ Systems?
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Neurologic: Brain structures, spinal cord
Cardiac: Four chamber heart, outflow tracts GI: stomach Renal: bladder, kidneys Limbs Genitalia Umbilical Cord Insertion Site |
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is ultrasound screening diagnostic for chromosomal abnormalities?
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NO!!
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Can ultrasound screening detect fetal abnormalities associated with chromosomal abnormalities?
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yes:
trisomy 21, 18, 13, or 45X among others The same abnormalities may occur as isolated findings in chromosomally normal fetuses |
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what are the major congenital abnormalities that can be screened for w/ ultrasound?
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Heart defects
Neural tube defects Abdominal wall defects Cystic hygroma +/- hydrops Renal malformations Intracranial malformations Skeletal abnormalities Etc., etc. |
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what Chromosomal Disorders are Associated Ultrasound Findings?
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Trisomy 21
Trisomy 18 Trisomy 13 Turner syndrome Triploidy Unbalanced chromosome rearrangements |
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when is 1st trimester screening performed?
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Ideally performed between 11 and 13 weeks
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what's good about 1st trimester screening?
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Provides risk assessment for Down syndrome and trisomy 18
First trimester maternal serum screening plus the measurement of subcutaneous edema of the fetal neck by ultrasonography (fetal nuchal translucency - NT) |
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what does the maternal serum screen measure in 1st trimester screening?
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pregnancy-associate plasma protein A (PAPP-A) and the hormone, human chorionic gonadotropin (hCG)
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if Isolated Increased Nuchal Translucency In chromosomally NORMAL fetuses, is a second trimester extensive ultrasound, and fetal echo are recommended?
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yes!
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what is the second trimester screening?
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Anatomic Ultrasound
Triple Screen or Quad Screen MS-AFP Free b-hCG Unconjugated estriol +/- inhibin A |
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what can Second Trimester Maternal Serum Screening show?
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Detection rates for autosomal trisomies (13, 18, 21)
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what might Unexplained Elevations of MS-AFP or b-hCG show?
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Incorrect gestational age
Multiple gestations (i.e. twins, triplets) Preeclampsia Abruption Premature labor SGA – small for gestational age Undiagnosed fetal anomalies Recent fetal demise Stillbirth Placental dysfunction |
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what results in triple screen indicate trisomy 21?
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Elevated b-hCG
Low Estriol (uE3) Low AFP |
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what results in quad screen indicate trisomy 21?
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Elevated Inhibin A
Elevated b-hCG Low Estriol (uE3) Low AFP |
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what screening results indicate trisomy 18?
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All serum markers are low
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are maternal serum markers and ultrasound assessment definitive diagnostic tests?
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NO!
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what do negative screening results suggest?
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that the risk for having a child with Down syndrome, another autosomal trisomy, or an ONTD is reduced, but is not zero
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what is this?
Methods of prenatal diagnosis aimed at assessment of specific populations May involve non-invasive and/or invasive methods Not intended for the normal pregnancy with normal primary screening |
secondary prenatal diagnosis
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what does this indicate:
Advanced maternal age > 35 Family history of chromosome abnormality Family history of genetic disorder diagnosed by biochemical or DNA analysis Family history of birth defects Increased risk of neural tube defect (NTD) Abnormal fetal ultrasound Abnormal maternal serum screening Maternal medical condition, teratogenic exposure, or congenital anomaly |
you should do a secondary prenatal diagnosis
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what are the 3 phases of the secondary prenatal diagnosis?
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Identification of at-risk pregnancies
Past medical and pregnancy histories, family history, abnormal routine screening tests Thorough risk assessment and genetic counseling Discussion of diagnostic procedures and availability of testing to corroborate the etiology of the underlying problem |
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what risk assessments and genetic counseling should be offered to couple concerning secondary prenatal diagnosis?
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Risk that the fetus will be affected
Nature and probable consequences for the affected fetus and the family Risks and limitations of the procedures Time limitations for generation of reports Possibilities for failure or repeat procedures Interpretation issues Options for the couple with an affected fetus |
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what are the non-invasive methods of prenatal diagnosis?
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Extensive Ultrasound
Fetal Echocardiography |
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what are the invasive methods of prenatal diagnosis?
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Amniocentesis
Chorionic villus sampling Percutaneous Umbilical Blood Sampling (PUBS) or Cordocentesis |
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what's the ultrasounds mostly used for?
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detection of structural abnormalities.
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what are the advantages of using ultrasound in diagnosis?
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Approximately 90% of the congenital heart defects can be detected by thorough ultrasound evaluation.
US is particularly sensitive in detecting ONTD. One major advantage, is that it allows identification of malformation patterns without distortion of the fetal environment. |
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what's the disadvantage in using ultrasound in diagnosis?
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does not pick up all birth defects.
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what is a Procedure for removing a sample of amniotic fluid transabdominally ?
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amniocentesis
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what is fluid from amniocentesis used for?
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Fetal cells are cultured from this fluid and analyzed
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when is an amniocentesis performed? what is the most common time frame?
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May be performed as early as 11 weeks, and all the way through until term
*Most commonly performed at 15-19 weeks |
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what are the risks of amniocentesis?
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1/1600 (0.6%) risk of miscarriage
Uterine cramping Transient spotting Infection (rare) Spontaneous rupture of membranes Blood group sensitization (RhoGAM) Remote chance of fetal injury in early amniocentesis (10 to 14 weeks) |
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when is clubfoot seen?
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seen in early amnio and CVS at 9 weeks
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what is Withdrawal of small amount of chorionic tissue?
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Chorionic Villus Sampling (CVS)
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how do you get biopsy for CVS?
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Biopsy obtained trans-cervical or trans-abdominal
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WHEN do you get CVS done?
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11-12 weeks of pregnancy
Early results allow early intervention if desired |
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can CVS assay maternal serum markers?
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NO!
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what are the risks in CVS?
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1/100-1/200 (1.0 to 0.5%) risk of miscarriage
Uterine cramping or vaginal bleeding Infection (~1%) Limb abnormalities (<1/3000 before 11 weeks) Blood group sensitization |
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what are the contraindications of CVS?
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Threatened Abortion
Maternal STD infection Uncertain gestational dating Maternal anatomic abnormalities |
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how accurate is a CVS?
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Chromosome analysis (99%)
Mosaicism (~1%) Maternal cell contamination |
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what do you follow up a CVS with?
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MSAFP to screening after 15 weeks
Ultrasound at 16-20 weeks |
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when is PUBS performed?
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Performed at 19 to 21 weeks of pregnancy
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what is PUBS?
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Percutaneous umbilical blood sampling
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what are the risks of PUBS?
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Incidence of fetal loss due to the procedure is approximately 2 to 3%
Risk of fetal hemorrhage High risk of failure to obtain adequate specimen |
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WHAT IS Procedure to obtain a sample of fetal blood directly from the umbilical cord with ultrasound guidance?
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PUBS
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what are the uses of PUBS?
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to follow up an ultrasound exam that has shown some fetal abnormality
When culture of amniotic fluid cells fails or yields ambiguous results When DNA diagnosis of a disorder requires fetal plasma or blood cells |
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what's the incidence of down syndrome?
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1/800 live births
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what are the clinical features of down syndrome?
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Mild to moderate mental retardation
Characteristic facial appearance Congenital heart defects (40-50%) Gastrointestinal obstructions (10%) |
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what are the structural abnormalities found in ultrasound screening of down syndrome?
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Congenital heart defect
Duodenal atresia |
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what are the markers seen in ultrasound findings in down syndrome?
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Nuchal thickening
Echogenic bowel Shortened humerus and femur Echogenic intracardiac foci Renal pyelectasis Shortened middle phalanx of fifth finger Absent nasal bone |
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what's the incidence of trisomy 13?
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1/22,000 live births
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what are the symptoms of trisomy 13?
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Profound mental and motor retardation
Holoprosencephaly (2/3) Microcephaly Congenital heart defects (90%) Low set ears, cleft lip/palate, polydactyly |
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what are the ultrasound findings for trisomy 13?
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Holoprosencephaly with associated findings
Cleft lip/cleft palate Polydactyly Congenital heart defect IUGR Omphalocele Urogenital anomalies Neural tube defect |
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what's the incidence for Turner syndrome?
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1/4000 female births
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what are the symptoms of turner syndrome?
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Short stature
Ovarian dysgenesis and infertility Webbed neck Normal IQ Renal and Cardiac defects |
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what's the prognosis for a baby w/ turner syndrome?
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>95% of 45,X conceptions result in miscarriage (cystic hygroma w/ hydrops )
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what are the ultrasound findings of turner syndrome?
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Cystic hygroma
Non immune hydrops Congenital heart defect (20%) Horseshoe kidney and other renal anomalies (60%) |
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when do neural tube defects occur?
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Occurs during 3rd to 4th week of fetal embryonic development
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what's the spectrum of neural tube defects?
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anencephaly and spina bifida
Severity and prognosis depends on location and extent of lesion |
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what does morbidity of neural tube defects include?
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Morbidity includes paralysis, incontinence, developmental delay
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what are ONTDs?
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open neural tube defects
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what's the incidence of ONTDs?
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1/1000 live births in U.S
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do babies w/ ONTDs usually have a family history of ONTDs?
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95% do not have a previous family history
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why does ONTD happen?
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12-15% due to chromosomal abnormalities, single gene defects, teratogens
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how can folic acid supplementation affect ONTD?
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Folic acid supplementation prior to conception can reduce individual risk by 50%
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Elevated _________ is associated with increased risk for ONTD
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MSAFP
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what does MSAFP stand for?
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maternal serum alpha-fetoprotein
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what's the sensitivity of MSAFP?
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Sensitivity: 80% for open spina bifida, and 90% for anencephaly
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will MSAFP detect closed neural defects?
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NO! Will not detect closed defects, but may detect other fetal defects
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when is MSAFP most accurate? what's the cutoff pt for accuracy?
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Most accurate between 16-18 wks, no normative values available after 20 weeks
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what's AFP influenced by?
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gestational age, maternal weight, race, diabetic status, multiple gestation
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what are cutoff values for MSAFP?
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2.0 MoM to 2.5 MOM
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what's the sensitivity for ultrasound detection of ONTDs?
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Sensitivity is 80-95%
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what are ass ultrasound findings of ONTDs?
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lemon sign, banana sign
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is hydrocephalus something that you see in ONTDs?
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Hydrocephalus occurs in majority, but may not appear until later
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how should Screening methods and tests be provided?
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through informed consent
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what is crucial prior to a procedure and after the test results are obtained?
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genetic counseling
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who is primary and secondary prenatal diagnosis available to?
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Primary prenatal diagnosis is available to all couples
Secondary prenatal diagnosis is offered in the event of increased risk |
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Pregnancy outcome may be altered after prenatal diagnosis and it is important to provide these couples with___________
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psychological support
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what questions should be answered prior to prenatal testing?
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Why do you think I should have this test?
What can this test tell me? What are the risks of this test? If the test finds a problem, how will it affect the baby? If the test finds the problem, what can be done? |
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what simplified questions basically need to ask couple?
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Do you want to know if there is anything wrong with your baby before it is born?
How far are you willing to go to find out? Will you consider termination for an abnormal fetus? |
