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OB/GYN 303 > Module 6: Chromosomal Abnormalities > Flashcards

Module 6: Chromosomal Abnormalities Flashcards

1
Q

What is the most common abnormality among spontaneously aborted fetuses?

A

Turner’s (45xo)

95% are aborted

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2
Q

What is non-disjunction?

A

The meiotic error that causes aneuploidy where a chromosome pair fails to separate during meiosis.

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3
Q

What is the value of mild renal dilation?

A

Greater than or equal to 5mm

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4
Q

What is the prognosis of T13?

A

Lethal/poor

70% are still born
85% die in 1st year

Survivors = profound mental retardation

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5
Q

What is another name for T18?

A

Edward syndrome

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6
Q

What heart defects are seen with T13?

A
  • VSD

- Hypoplastic left heart

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7
Q

What are the levels on the triple screen in the presence of T18?

A

MS-AFP decreased

uE3 decreased

B hCG decreased

(All decreased)

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8
Q

What heart defect is most common in T18?

A

Large VSD

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9
Q

What is PAPP-A?

A

Pregnancy Associated Plasma Protein A

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10
Q

Why are autosomal trisomies rarely seen?

A

Lethal (SA)

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11
Q

How can clinodactyly be identified on U/S?

A

Overlapping digits in fist

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12
Q

What is another name for T13?

A

Patau syndrome

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13
Q

What is the triple screen detection rate of trisomy 21?

A

60%

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14
Q

What is the prognosis of Turners babies that survive birth?

A

Few life threatening anomalies and normal intellect

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15
Q

What increases the risk of T13?

A

Advanced maternal age

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16
Q

How often do chromosomal abnormalities occur?

A

1/160 live births

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17
Q

What increases the risk of trisomy 21?

A

Maternal age

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18
Q

What is a marker for Triploidy?

A

Markedly high BhCG (8x higher than normal)

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19
Q

What is Micrognathia?

A

Underdeveloped jaw

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20
Q

What is the chromosome make-up in aneuploidy?

A

A sperm or oocyte has 2 copies of a particular chromosome or no copies instead of one copy in the haploid state.

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21
Q

What is Cystic hygroma?

A

Multiple cysts in lymphatic system

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22
Q

What is the 2nd most common chromosome abnormality at birth?

A

T18/Edwards

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23
Q

How common is trisomy 21?

A

1/700 births

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24
Q

What is the level of PAPP-A in the presence of T21?

A

Decreased

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25
Q

What is triploidy NOT associated with unlike the other trisomys?

A

Maternal age

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26
Q

What are the biochemical markers at 1st trimester screen?

A
  • B-hCG

- PAPP-A

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27
Q

Once fertilized how may chromosomes are present in aneuploidy?

A

45 or 47

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28
Q

What is the most important LESS specific appearance of T18?

A

Strawberry shaped head

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29
Q

Does maternal age increase the risk of Turners?

A

No, maternal age is not a factor.

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30
Q

What is turners syndrome?

A

Missing one of the sex chromosomes (an x or a y from the paternal side) (45xo)

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31
Q

What is Alobar Holoprosencephaly? (4 points)

A
  • Little to no cortical mantle
  • Single Horseshoe ventricle
  • Fused thalami
  • Absent 3rd ventricle and falx
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32
Q

What is the major cause of increased infant mortality in trisomy 21?

A

Cardiac abnormalities

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33
Q

What is duodenal atresia known as?

A

“Double bubble”

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34
Q

What substances are tested in the quad screen?

A
  1. AFP
  2. uE3
  3. B-hCG
  4. Inhibit A
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35
Q

Look at the images

A

…

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36
Q

What is aneuploidy?

A

“Bad set” - State of having abnormal number of chromosomes (1 extra or 1 less).

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37
Q

What gender are people with Turners and what condition are they all affected by?

A

All are females and all are sterile

38
Q

What is the poor prognosis of T18 due to?

A

Heart and GI defects

39
Q

What heart defect is common with Turner’s?

A

Coarctation of the aorta

40
Q

How often are triploidy cases due to a diploid egg?

A

40 %

41
Q

What is the specific US appearance of Trisomy 21? (6)

A
  1. Thick nuchal fold
  2. Heart defect
  3. Mild renal dilation
  4. Duodenal atresia
  5. Tracheoesophageal fistula
  6. Shortened long bones
42
Q

What is lobar Holoprosencephaly? (2)

A
  • Fused anterior horns that are squared off

- Incomplete falx and 3rd ventricle

43
Q

How often are triploidy cases fertilized with two sperm?

A

60%

44
Q

What is the medical term for mild renal dilation?

A

Pelviectasis/Pyelectosis

45
Q

What is the prognosis of T18?

A

Almost always lethal

50% die in 1st 2 months
95% die in 1st year

46
Q

How does the prognosis of triplody differ between paternal and maternal?

A

Paternal = Half will miscarry

Maternal = More live births than paternal

47
Q

What is hypotelorism?

A

Abnormally close eyes

48
Q

What is the specific U/S appearance of T18? (6)

A
  • Choroid plexus cysts
  • Early onset of symmetric IUGR with poly hydramnios
  • Clenched fists/clinodactyly
  • Club feet
  • Rocker bottom feet
  • Heart defects
49
Q

What is clinodactyly?

A

An abnormal

50
Q

What is uE3?

A

Unconjugated estriol

51
Q

How does the hCG levels differ between paternal and maternal triploidy?

A

Paternal = increased hCG

Maternal = low in 2nd trimester due to small placenta

52
Q

What is semilobar Holoprosencephaly? (4 points)

A
  • Brain mantle present
  • Single horseshoe ventricle
  • Incomplete fusion of thalami
  • Absent falx and 3rd ventricle
53
Q

What is Microphthalmia?

A

One or both eyes are abnormally small

54
Q

What are the 3 classifications of Holoprosencephaly?

A
  1. Lobar
  2. Semilobar
  3. Alobar
55
Q

How does IUGR differ between maternal and paternal triploidy?

A

Paternal = small symmetrical IUGR

Maternal = asymmetric IUGR

56
Q

What are the levels on the triple screen in the presence of T21?

A

MS-AFP decreased

UE3 decreased

B hCG increased

57
Q

What is radial ray syndrome?

A

Absent radius resulting in clubbed hand

58
Q

What is Holoprosencephaly?

A

A severe abnomality that occurs when the forebrain fails to develop into two separate hemispheres

59
Q

What abnormality is NOT detected with triple screen?

A

T13

60
Q

What heart defects are common with Trisomy 21? (4)

A
  • AVSD
  • VSD
  • ASD
  • Echogenic foci in LV or RV
61
Q

What are the less specific US appearances of T21? (7)

A
  • Cystic hygroma
  • Non immune hydrops
  • Clinodactyly
  • Echogenic bowel
  • Omphalocele
  • Mild ventriculomegaly
  • Sandal foot toes
62
Q

What is hydrops?

A

Severe edema of the fetus

63
Q

How does the placenta differ between maternal and paternal triploidy?

A

Paternal = Large cystic placenta

Maternal = small placenta

64
Q

What are the U/S appearances of triploidy? (11)

A
  • Holoprosencephaly
  • Agenesis of the corpus callosum
  • Meningomyelocele
  • Arnold Chiari malformation
  • Ventriculomegaly
  • Heart defects
  • Facial clefts
  • Syndactyly
  • Club feet
  • Cystic hygroma
  • Omphalocele
65
Q

What is turners syndrome called?

A

Monosomy

66
Q

What is the most common live born abnormality?

A

Trisomy 21 (downs syndrome)

67
Q

What is coarctation of the aorta?

A

An abnormal narrowing of the descending aorta (ductus arteriosis area).

68
Q

What are the less specific sonographic features of T13? (8)

A
  • Polydactyly
  • Clinodactyly
  • Club feet
  • Rocker bottom feet
  • Cystic hygroma
  • Severe heart defects
  • Polycystic kidneys (echogenic kidneys)
  • Enlarged cisterna magna
69
Q

What is increased Inhibin suggestive of?

A

Down syndrome

70
Q

What eye defects occur with T13?

A
  • Microphthalmia
  • Hypotelorism
  • Cyclopia
71
Q

What bones will be shortened in T21?

A

Long bones:

Femur and humerus

72
Q

What is the specific U/S appearance of T13? (6)

A
  • Midline defects (holoprosencephaly)
  • Cleft lip/palate
  • Eye defects
  • Proboscis or absent nose
  • Omphalocele
  • Microcephaly/IUGR
73
Q

What is Triploidy associated with?

A

Partial molar pregnancy

74
Q

What are the less specific US appearances of T18? (9)

A
  • Strawb head
  • Cleft lip/palate
  • Omphalocele
  • Diaphragmatic hernia
  • Single umbilical artery
  • Radial ray syndrome
  • Micrognathia
  • Cystic hygroma
  • Enlarged cysterna magna
75
Q

What is proboscis?

A

Large, elongated nose

76
Q

What is the occurrence/prognosis of Triploidy?

A

Rare and usually lethal

77
Q

How common is T13?

A

1 in 5000-10000 births

78
Q

What is triploidy?

A

Form of polyploidy, complete extra set of chromosomes (69xxy)

79
Q

What are the specific U/S features of Turner’s? (6)

A
  • Cystic Hygroma with septations
  • Hydrops
  • Heart defects
  • Renal agenesis
  • Horseshoe kidney
  • Pelvic kidney
80
Q

What substances are tested with triple screen?

A
  1. MS-AFP
  2. B hCG
  3. UE3
81
Q

What are the textbook stats for maternal/paternal triploidy?

A

Paternal = 90%

Maternal = 10%

82
Q

What is T18 associated with?

A

Late maternal age

83
Q

What is trisomy?

A

One extra complete or partial chromosome (47xy)

84
Q

What is B-hCG?

A

Beta human chorionic gonadotropin

85
Q

What is syndactyly?

A

When one or more digits are fused

86
Q

What abnormalities can be detected with triple screen?

A

T21 and T18

87
Q

What will be increased in the presence of tracheoesophageal fistula?

A

Increased AFI

88
Q

What is the term for triploidy resulting from a diploid egg?

A

Maternal/digyny

89
Q

What is the term for triploidy resulting from two sperm?

A

Paternal/diandry

90
Q

How common is T18?

A

1 in every 3000-5000 births

91
Q

What is euploid?

A

Means “good set” - Having a normal number of chromosomes.

OB/GYN 303 (21 decks)

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