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OB 2 > The Prenatal Genetic: Workup At Risk > Flashcards

The Prenatal Genetic: Workup At Risk Flashcards

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1
Q

What are the indications for prenatal genetic testing?

A
  • Advanced maternal age (AMA) of 35 or greater at delivery
  • Family history of congenital abnormalities
  • Prior pregnancy with congenital abnormality
  • Prenatal exposure to noxious substances
  • Maternal diabetes

These factors increase the risk of genetic abnormalities in the fetus.

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2
Q

What is the triad of diagnostic prenatal testing?

A
  • Maternal serum markers (blood tests)
  • Invasive procedures: Amniocentesis (amnio) and Chorionic villus sampling (CVS)
  • OB ultrasound/First Trimester

This triad helps in assessing the risk of genetic anomalies.

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3
Q

What is the purpose of maternal serum testing?

A

To identify variations in pregnancy-produced substances circulating in the maternal blood that are statistically associated with congenital abnormalities.

This testing helps in early detection of potential issues.

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4
Q

What substances are included in the Quad Marker Screen Test?

A
  • hCG
  • Estriol
  • Inhibin A
  • Maternal serum alpha-fetoprotein (MSAFP)

These markers are tested to assess the risk of congenital anomalies.

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5
Q

What does a high level of Maternal Serum Alpha-Fetoprotein (AFP) indicate?

A
  • Incorrect gestational age
  • Multiple gestations
  • Open neural tube defects
  • Open abdominal wall defects
  • Esophageal and duodenal atresia
  • Placental abruption
  • Maternal co-morbidity

High AFP levels can indicate various fetal and maternal conditions.

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6
Q

What are the indications for amniocentesis?

A
  • Abnormal Quad screen blood test results
  • Previous fetus with aneuploidy
  • Parental balanced translocation
  • X-linked recessive disorders
  • Other genetic disorders
  • Fetal anomalies seen on imaging
  • Evaluation for intrauterine infection
  • Rh isoimmunization
  • Fetal sex identification
  • Polyhydramnios
  • Paternity testing

Amniocentesis is performed for various diagnostic purposes.

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7
Q

What are the risks and complications associated with Chorionic Villus Sampling (CVS)?

A
  • Miscarriage (0.5% loss rate)
  • Perforation of the amniotic sac
  • Unexplained mid-trimester oligohydramnios
  • Limb reduction defects
  • Rh sensitization
  • Maternal sepsis

CVS is associated with specific risks, particularly related to the timing and method of the procedure.

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8
Q

What is the normal value for Nuchal Translucency measurement?

A

Less than 2.5 mm

Nuchal translucency is measured between 11-14 weeks of gestation as a marker for aneuploidy.

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9
Q

What are soft markers for Trisomy 21?

A
  • Hyperechogenic bowel
  • Echogenic intracardiac foci
  • Choroid plexus cysts
  • Renal pyelectasis
  • Absent nasal bone
  • Nuchal thickening

These markers can indicate an increased risk for Down syndrome.

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10
Q

What is the significance of Nuchal Thickness measurement?

A

Good correlation with the risk of Down syndrome (trisomy 21) when adjusted for advanced maternal age (AMA).

Nuchal thickness is assessed in the second trimester and is a reliable marker for genetic abnormalities.

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11
Q

What does echogenic bowel indicate?

A
  • Associated with trisomies 13, 18, and 21
  • Cystic fibrosis
  • Congenital infections
  • Congenital malformations of the bowel
  • Intra-amniotic hemorrhage
  • Meconium ileus
  • Perinatal complications

Echogenic bowel is a significant finding that may require further investigation.

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12
Q

What is the normal range for renal pyelectasis during pregnancy?

A
  • 18-20 weeks: greater than 4.0 - 4.5 mm
  • 20-29 weeks: greater than 5.0 mm
  • 30-32 weeks: greater than 6.0 mm
  • 33-term: greater than 7.0 mm

Pyelectasis can indicate potential issues if measurements exceed normal values.

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13
Q

True or False: The nasal bone is a soft marker for several genetic syndromes.

A

True

Standardized measurements of the nasal bone can help assess the risk of genetic conditions.

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14
Q

What is the significance of renal pyelectasis values at 30-32 weeks?

A

Greater than 6.0 mm

Renal pyelectasis is a condition characterized by dilation of the renal pelvis.

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15
Q

What measurement indicates renal pyelectasis at 33-term weeks?

A

Greater than 7.0 mm

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16
Q

What are the sono signs of renal pyelectasis?

A
  • Unilateral or bilateral renal pelvis dilation
  • Resolves spontaneously by 26 weeks
  • No associated caliectasis or ureteral dilation
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17
Q

What distinguishes pyelectasis from hydronephrosis?

A

Pyelectasis is when the pelvis is stretched or enlarged, but not enough to diagnose hydronephrosis

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18
Q

Define aneuploidy.

A

Presence of an abnormal number of chromosomes in a cell

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19
Q

What is the typical human karyotype?

A

23 pairs of chromosomes (46 total): 22 autosomal sets and 1 sex set

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20
Q

What is a single-gene disease?

A

Medical conditions arising from a single gene, occurring in about 1% of all newborn infants

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21
Q

What is an autosomal recessive disorder?

A

Defective copy of the gene is contributed by each parent

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22
Q

What is an autosomal dominant disorder?

A

Only one defective gene is required to cause the associated disease

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23
Q

What is a triploidy?

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A

Presence of 3 chromosomes across the karyotype for a total of 69 instead of the normal 46

24
Q

What is trisomy?

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A

Presence of 3 chromosomes instead of the normal 2

25
What is monosomy?
The lack of 1 chromosome of the normal complement
26
What is Turner syndrome?
A congenital genetic condition in which one of the sex chromosomes is absent while the other is an X chromosome
27
What are some associated abnormalities of Turner syndrome?
* IUGR * Shortened Limbs * Cardiac anomalies: coarctation of aorta, bicuspid aortic valve
28
What is Beckwith-Wiedemann Syndrome?
Congenital overgrowth syndrome resulting in macroglossia, enlarged internal organs, and omphalocele
29
What are the common cardiac anomalies associated with Trisomy 21?
* Endocardial cushion defect * VSD * Atrial septal defect
30
What is the incidence of Trisomy 21 in live births?
1 in 600-800 newborns
31
What are soft sono markers for assessing Down syndrome?
* Nuchal fold thickening * Hyperechoic bowel * Mildly shortened femur and/or humerus * Echogenic intracardiac foci * Fetal pyelectasis
32
What are the main characteristics of Trisomy 18?
* Median survival is 2.5-14.5 days * 90-95% do not survive the first year
33
What are common anomalies associated with Trisomy 18?
* Cardiac: Atrial septal defects, VSD * CNS: Dandy-Walker malformation, neural tube defects * Face and neck: Short neck, prominent occiput, micrognathia
34
What are the common anomalies of Trisomy 13?
* Cardiac: Hypoplastic left heart syndrome, VSD * CNS: Holoprosencephaly, agenesis of the corpus callosum * Face and neck: Micrognathia, cleft lip/palate
35
What is the incidence of Trisomy 13 in live births?
1 in 13,000-20,000 live births
36
What is Amniotic Band Syndrome?
Collection of multiple bizarre anomalies caused by constricting bands of amniotic tissue
37
What are the syndromal findings associated with Amniotic Band Syndrome?
* Limb defects * Craniofacial defects * Visceral defects
38
What is Sirenomelia also known as?
Mermaid Syndrome
39
What are common anomalies associated with Sirenomelia?
* Renal agenesis * Abdominal wall defects * Single umbilical artery
40
What are the sonographic markers for Trisomy 18?
* Brachycephaly * Choroid Plexus Cysts
41
What are the common associated abnormalities of Meckel-Gruber Syndrome?
* Renal cystic dysplasia * CNS anomalies * Developmental defects of the liver
42
What is orchidism?
A condition characterized by the absence of one or both testes. ## Footnote Orchidism can lead to various associated abnormalities.
43
What is rhizomelic shortening of the limbs?
A type of limb shortening characterized by disproportionate shortening of the proximal segments of the limbs. ## Footnote It can be associated with various congenital disorders.
44
What are common associated abnormalities with limb shortening?
* Pulmonary hypoplasia * Cardiac anomalies (50%) ## Footnote Cardiac anomalies may not always be present.
45
What is Meckel-Gruber Syndrome?
A lethal autosomal recessive disorder characterized by renal cystic dysplasia, CNS anomalies, liver defects, and pulmonary hypoplasia due to chronic oligohydramnios. ## Footnote Occurs in approximately 1 in 13,250 to 140,000 live births.
46
What are the key renal features of Meckel-Gruber Syndrome?
The kidneys appear similar to polycystic renal disease, with renal parenchyma replaced by cysts of varying size. ## Footnote This leads to the elimination of normal renal function.
47
How does oligohydramnios contribute to mortality in Meckel-Gruber Syndrome?
Lack of amniotic fluid causes fetal lungs to fail to mature, leading to pulmonary hypoplasia. ## Footnote This is a significant factor in the assured mortality associated with the syndrome.
48
What are the syndromal findings in Meckel-Gruber Syndrome?
* Polydactyly * Cystic dysplastic kidneys * Holoprosencephaly/encephalocele ## Footnote These findings aid in the diagnosis of the syndrome.
49
What is VACTERL Association?
A constellation of nonrandom congenital anomalies arising from the embryonic mesoderm. ## Footnote The cause is unknown.
50
What does the acronym VACTERL stand for?
* V - Vertebral anomalies * A - Anorectal anomalies * C - Cardiac anomalies/Cleft lip * T - Tracheoesophageal fistula * E - Esophageal atresia * R - Radial ray anomalies * L - Limb anomalies ## Footnote These anomalies occur simultaneously in a fetus.
51
What are common sono signs of VACTERL Association?
Polyhydramnios and various other listed anomalies. ## Footnote Also includes lumbosacral hemivertebrae and radial ray anomalies.
52
What does CHARGE stand for?
* C - Coloboma * H - Heart defects * A - Atresia (Choanal) * R - Retardation (mental) * G - Genital hypoplasia * E - Ear abnormalities/deafness ## Footnote CHARGE is sometimes classified as a syndrome.
53
What are associated anomalies of CHARGE Association?
* Microphthalmia * Anophthalmia * Facial clefts * IUGR * Congenital renal anomalies * Esophageal/tracheoesophageal fistula ## Footnote These anomalies can occur alongside the features of CHARGE.
54
What is Tetralogy of Fallot?
A congenital heart defect characterized by four specific heart anomalies. ## Footnote It includes pulmonary artery stenosis, ventricular septal defect, right ventricular outflow tract obstruction, and right ventricular hypertrophy.
55
What are the sonographic findings in Tetralogy of Fallot?
* Y-shaped overriding aorta * Outflow from both ventricles * VSD * Right ventricular outflow anomalies * Right ventricle hypertrophy ## Footnote These findings help in the diagnosis of Tetralogy of Fallot.

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