Prenatal Growth Defects and Dx Flashcards

1
Q

When is a baby considered pre-term?

A

Born before 34 weeks (38 normal pregnancy)

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2
Q

When are the organ systems of the fetus well-established?

A

By the second month of gestation

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3
Q

When does the embryo gain the most length and weight?

A

Length: 3-6 months gestation

Weight: 7-9 months gestation

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4
Q

Low birth weight

A

Less than 5 lbs. 8 oz.

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5
Q

SGA and IUGR

A

Small for gestational age (SGA)

Intrauterine growth restriction (IUGR)

At or below 10th %

Toxic insult/hereditary - one of most common causes is multiple births

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6
Q

Barker’s hypothesis

A

Obesity
Hypertension
Hypercholesterolemia
Type 2 Diabetes
Cardiovascular Disease

(IUGR) - produces problems as adults

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7
Q

Twins

A

7-11/1000 dizogotic

3-4/1000 monozygotic

Only 29% of women pregnant with twins give birth
10-20% die at birth
12% of premature infants are twins
ARTs = 1-2% of all pregnancies = more multiple birth pregnancies

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8
Q

Dizygotic twinning

A

Two separate embryos, typically separate placentas (sometimes they fuse)

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9
Q

Twin transfusion syndrome

A

One embryo receives too much blood supply the other too little

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10
Q

Defects of the primitive streak

A

Can produce conjoined twins

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11
Q

When is the appearance and dissapearance of the herniated gut loop common?

A

Appearance: wk 6

Dissapearance (reduces): wk 10

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12
Q

At what point in gestation is a fetus viable outside of the womb?

A

7 months (when lungs begin to make surfactant)

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13
Q

Types of birth defects

A

Malformations: Most occur during the 3rd-8th weeks, but the 1st 2 weeks are important too!

Disruptions: Alterations in already formed structures(vascular accidents, amniotic bands)

Deformations: Mechanical forces alter a structure (Potter’s face - renal agenesis)

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14
Q

Abnormal gene signaling (classification of abnormal fetal development)

A

Malformation

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15
Q

Vascular accidents are classified as what type of malformation during fetal development?

A

Disruption

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16
Q

Amniotic bands

A

The amnion strands wraps around and constricts blood floow (extrimities)

AER disruption can also produce similar effects

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17
Q

Causes of birth defects

A
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18
Q

Microarrays

A

Specific DNA sequences hybridized to patient’s DNA or RNA. Detects mutations and changes in expression.

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19
Q

Exome sequencing

A

Sequencing coding regions (exons) of a patient’s DNA where most genetic variants occur and which represent only about 1% of a patient’s total DNA.

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20
Q

Increased incidence of trisomy 21 with increasing maternal age:

A

Age 25 = 1/2000

35 = 1/300

40 = 1/100

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21
Q

Turner syndrome

A

45 X monosomy

22
Q

Angelman Syndrome

A

15q11-15q13: maternal deletion (imprinting)

23
Q

Thalidomide

A

Characteristic limb defects (absence of the long bones)

24
Q

Zika virus

A

Can cause necrosis of brain tissue (microcephaly)

25
Q

Environmental causes of defects

A

Alcohol
Retinoids (acutane)
Thalidomide
Antieplileptic drugs (dilantin, valproic acid)
Radiation
Infections (Hyperthermia- even hot tub use)
Maternal diabetes
Obesity
Nutrional deficiencies
SSRIs
Zofran (heart defects)

26
Q

Things that affect whether or not a teratogen affects outcome:

A

Maternal and infant genotype

Developmental stage at time of exposure

Dose and duration of exposure

Mechanism of action and pathogenesis

27
Q

Microtia (small ears)
Birth Mark (pigmented area)

A

May indicate other abnormalities

One = 3% chance of a major defect
Two = 10% chance of a major defect
Three or more =20% chance of a major defect

28
Q

Prenatal Dx

A

Ultrasound

Maternal Serum Screening(Alpha-Feto-Protein; AFP)
NTDs, Omphaloceles, Ventral body wall defects, etc.
Down syndrome, Trisomy 18, Sex Chromosome Abnormalities

Non-invasive prenatal screening (NIPS: Cell free DNA)

Amniocentesis(Genetics, AFP, Ach)

Chorionic Villus Sampling (Genetics)

Older women(>35), History of birth defects, Chromosome anomalies

29
Q
A

6 week embryo

30
Q
A

Two gestational sacs

31
Q
A

Neural tube failing to close (spina bifida)

32
Q

How does folic acid prevent defects?

A

Dr. Sadler’s lab - believes that it affects DNA synthesis

Otherwise methylation (epigenetic control)

Prevents following defects:

NTDs (up to 70%)
Craniofacial
Urogenital
Cardiac

33
Q
A

Trisomy 21 (Down syndrome)

34
Q
A

Thalidomide

35
Q

When would you risk invasive prenatal testing?

A

If a woman was of advanced maternal age

If there was an abnormal ultrasound or serum screening test

If there was a family history of genetic problems

36
Q

What percentage of women pregnant with twins actually give birth sucessfully?

A

30%

37
Q
A

End of 8 weeks gestation

38
Q

What is the difference between small for gestational age (SGA) and intrauterine growth restriction (IUGR)?

A

SGA means small, but normal: IUGR means exposure to a toxic factor

39
Q

When an infant is born before surfactant is produced

A

Neonatal respiratory distress syndrome

40
Q
A

**Twin transfusion syndrome
**
Occurs when the placentas of twins grow too close together and begin to share a common blood supply.

41
Q

What is the most common malformation?

and Rate

A

Heart defects (1:100)

Most common is VST

42
Q

Neural tube defects

Rate

A

1:1000

43
Q

Cleft palate

Rate

A

1:700

44
Q

How does maternal insulin-dependent diabetes induce birth defects?

A

Combination of toxic factors:

Ketones
Hyper/hypoglycemia
Growth inhibiting substances

45
Q

What can cause elevated alpha-fetoprotein during gestation?

A

Omphalocele - a birth defect in which the infant’s intestine or other abdominal organs protrude through a hole in the belly button area and are covered with a membrane.

46
Q

What growth factor signaling is disrupted by talidomide?

A

Fibroblast growth factor (FGF)

Limb bud development begins at 4-5 weeks gestation

47
Q
A

Increased nuchal translucency indicates genetic disease (commonly seen in Down syndrome)

47
Q

What organ is most vulnerable to toxic insult after 8 wks gestation?

A

The brain

48
Q

Noninvasive prenatal screening

A

Cell free DNA (cfDNA) from maternal blood

49
Q

What prenatal screening tests can be performed at 14 weeks gestation?

A

Percutaneous umbilical blood sampling (PUBS)
Amniocentesis

50
Q

When can chorionic villus sampling (CVS) be performed?

A

The 8th week gestation