Module 10: Fetal Skeletal Dysplasia's Flashcards Preview

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Flashcards in Module 10: Fetal Skeletal Dysplasia's Deck (62)
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1
Q

When does endochondral ossification begin?

A

10 menstrual weeks

2
Q

When do the mandible and maxilla ossify?

A

8 to 10 menstrual weeks

3
Q

When does the clavicle ossify?

A

After the mandible and maxilla

4
Q

ALL long bones ossify by the end of when?

A

1st trimester

5
Q

Secondary epiphyseal ossification of the distal femur should occur when?

A

32 weeks or greater

6
Q

Secondary epiphyseal ossification of the distal humerus should occur by?

A

> 38 weeks

7
Q

What may delay the progression of the secondary epiphyseal ossification center?

A

IUGR

8
Q

What is the femoral growth rate until 27 weeks?

A

3 mm/wk

9
Q

What is the femoral growth rate from 28 weeks until term?

A

1 mm/wk

10
Q

What are four indications for skeletal dysplasia?

A

Specific genetic risk, apparent limb abnormality, associated abnormality, abnormal amniotic fluid level

11
Q

What are the three errors of morphogenesis?

A

Malformation, deformation, and disruption

12
Q

What does malformation mean in terms of errors of morphogenesis?

A

Abnormal formation of tissue (could be genetic or due to maternal drug use)

13
Q

What does deformation mean in terms of errors of morphogenesis?

A

Normally developed, but abnormal force alters structure shape

14
Q

What is something that could cause deformation?

A

Oligohydramnios

15
Q

What does disruption mean in terms of errors of morphogenesis?

A

Normally developed, but abnormal interference causes tissue destruction

16
Q

What are some examples of disruption?

A

Vascular occlusion (limb reduction), and tearing (amniotic bands) causing tissue destruction

17
Q

What are the five patterns of shortening?

A

Rhizomelia, mesomelia, acromelia, micromelia, and phocomelia

18
Q

What is rhizomelia?

A

Shortening of the proximal portion of limbs

19
Q

What is mesomelia?

A

Shortening of the middle portion of limbs

20
Q

What is acromelia?

A

Shortening of the distal portion of limbs

21
Q

What is micromelia?

A

Shortening of all portions of limbs

22
Q

What is phocomelia?

A

Shortening of the hands and feet attached to the body

23
Q

How many standard deviations are shortened bones?

A

> 4

24
Q

What kind of follow up would a 2-4 SD require?

A

Follow up in 2-4 weeks to ensure normal growth

25
Q

Which dysplasia’s have a better diagnosis?

A

Ones that manifest later with less severe features

26
Q

What should the femur measure at 18 weeks?

A

2.5 cm

27
Q

What comparison can help assist in the diagnosis of a skeletal dysplasia?

A

Comparison of the long bones to fetal feet

28
Q

Lethal skeletal dysplasias can be what two things?

A

Sporadic dominant or AR inheritance pattern

29
Q

What are three common lethal skeletal dysplasias?

A

Thanatophoric dysplasia, achondrogenesis, osteogenesis imperfecta II

30
Q

What are three rare lethal skeletal dysplasias?

A

Congenital hypophosphatasia, camptomelic dysplasia, homozygous achondroplasia

31
Q

What percentage of common lethal dysplasias are either thanatophoric or achondrogenesis?

A

60%

32
Q

When is a dysplasia considered lethal?

A

Severe micromelia, decreased thoracic circumference, pulmonary hypoplasia

33
Q

If you see ‘consanguinity’ on a req, what does it mean?

A

Couple are relatives (AR traits more prevalent)

34
Q

What is the most common skeletal dysplasia?

A

Thanatophoric dysplasia

35
Q

Thanatophoric dysplasia is a mutation of what?

A

FGFR3 (fibroblast growth factor receptor 3)

36
Q

What are the lethal features of thanatophoric dysplasia?

A

Micromelia, Kleeblattschadel (clover-leaf skull), narrow throax, and platyspondyly

37
Q

Which type of TD is most common?

A

Type I

38
Q

What does Type I TD include?

A

Extreme rhizomelia, bowed bones, normal trunk length, platyspondyly, and frontal bossing

39
Q

What does Type II TD include?

A

Straighter long bones, taller vertebral bodies, and Kleeblattshadel

40
Q

In what plane can Type II Kleeblattschadel be seen best?

A

Through the axial planes of the fetal brain

41
Q

What should the femur to foot ratio be in a normal fetus?

A

1

42
Q

What does platyspondyly describe?

A

Thin vertebral bodies with thick intervertebral spaces

43
Q

What can a narrow chest be referred to as?

A

Bell shaped chest

44
Q

What is seen with achondrogenesis?

A

Decreased mineralization

45
Q

Is achondrogenesis dominant or recessive?

A

Autosomal recessive (parents are often relatives)

46
Q

Which type of achondrogenesis is most common at what percent?

A

Type II at 80%

47
Q

Which type of achondrogenesis is more severe?

A

Type I

48
Q

What is the main difference between the lethality’s of Type I and II achondrogenesis?

A

Type I has abnormal cranial ossification while Type II has a normal cranium

49
Q

What are the sonographic features of achondrogenesis?

A

Micromelia, small throax, decreased mineralization, fractures and bowing of limbs, and may have severe hydrops

50
Q

Osteogenesis imperfecta describes defective what?

A

Collagen

51
Q

Which type of osteogenesis imperfecta is most common?

A

IIA at 80% and is lethal

52
Q

Which types of osteogenesis imperfecta are considered mild?

A

I, III, and IV

53
Q

What are examples of rare lethal skeletal dysplasias?

A

Congenital hypophosphatasia, camptomelic dysplasia, homozygous achondroplasia

54
Q

What is congenital hypophosphatasia?

A

Autosomal recessive abnormality that is characterized by abnormal bone mineralization due to alkaline phosphatase deficiency

55
Q

What can congenital hypophasphatasia mimic?

A

OI IIA

56
Q

Camptomelic dysplasia is also known as what?

A

Bent bone dysplasia

57
Q

What are features of comptomelic dysplasia?

A

Bowing of most long bones, club feet, absent or hypoplastic fibulae, narrow thorax

58
Q

What are examples of non-lethal skeletal abnormalities?

A

Heterozygous achondroplasia, asphyxiating thoracic dysplasia, and diastrophic dysplasia

59
Q

What are the features of heterozygous achondroplasia?

A

Moderate rhizomelia, large calvarium, frontal bossing, and normal thorax

60
Q

What is the most common non-lethal dysplasia?

A

Heterozygous achondroplasia

61
Q

What is asphyxiating thoracic dysplasia?

A

Moderate rhizomelia, long and narrow thorax, cystic renal dysplasia, and polydactyly

62
Q

What is another name for club foot?

A

Talipes equinovarus