fetal skeleton

1. The skeleton initially appears as ____________.

2. Then, it will later undergo __________.

1. Cartilaginous

2. Ossification

Skeletal dysplasia describes abnormal (1)_______ and (2)_______ of cartilage that results in bones that appear (3)__________, (4)______, (5)_________, or fail to form at all.

1. Growth

2. Density

3. Shortened

4. Thin

5. Deformed

When the sonographer evaluates the long bones, what 4 questions should they ask themselves?

• Are the bones mineralized correctly?

• Are they all present?

• Are the bones shortened?

• Are the bones bent or fractured?

Some skeletal dysplasias are lethal, meaning they are (1)____________ with life in their more (2)________ forms.

1. Incompatible

2. Severe

Nonlethal skeletal dysplasias tend to manifest in a ________ form.

Milder

Sometimes, abnormalities of the fetus can occur due to what 4 pathologies?

• Oligohydramnios

• Multiple gestations

• Uterine anomalies

• Amniotic band syndrome

A patient whose fetus is at risk for skeletal dysplasia will be referred for what?

A targeted US

Many skeletal dysplasias are (1)_________, but can also be (2)________.

1. Genetic

2. Sporadic

List the 7 evaluation factors for skeletal dysplasia.

• Assess limb shortening

• Assess bone contour

• Estimate degree of ossification

• Evaluate thoracic circumference and shape

• Survey for coexistent hand and foot anomalies

• Evaluate face and profile

• Survey for other associated anomalies (Heart defects and nonimmune hydrops)

When the sonographer is assessing limb shortening, all ______ bones should be measured.

Long

Skeletal dysplasia is suspected when limb length falls (1)________ than (2)___ standard deviations below the mean.

1. Greater

2. 2

What 3 findings should be noted when assessing bone contour?

• Thickness

• Abnormal bowing or curvature

• Fractures

What 2 factors an indicate hypomineralization?

• Decreased attenuation of bones

• Decreased shadowing

List 4 skeletal structures to pay close attention to.

• Cranium

• Spine

• Ribs

• Long bones

When evaluating thoracic circumference and shape, which 2 sonographic findings can indicate specific dysplasias?

• Long, narrow chest

• Bell-shaped chest

What is another term for bell shaped chest?

Champagne cork

When surveying hand and foot anomalies, which 2 pathologies should the sonographer look for?

• Talipes (club foot)

• Polydactyly

Why should the sonographer evaluate the face and profile?

To look for facial abnormalities

Rhizomelia is associated with what pathology?

Heterozygous achondraplasia

Rhizomelia is the (1)________ of the (2)________ segment of extremity.

1. Shortening

2. Proximal

Mesomelia is the (1)________ of the (2)________ segment of extremity.

1. Shortening

2. Middle

Acromelia is the (1)________ of the (2)________ segment of extremity.

1. Shortening

2. Distal

Micromelia is the (1)________ of the (2)________ limb of extremity.

1. Shortening

2. Entire

Phocomelia is the (1)________ of a (2)_______ of extremity.

1. Absence

2. Segment

Amelia is the (1)________ of the (2)_______ extremity.

1. Complete absence

2. Entire

Phocomelia will have either the _________ or _________ segment absent.

• Proximal

• Middle

What 2 structures are most commonly affected with rhizomelia?

• Humerus

• Femur

What 2 structures are most commonly affected with mesomelia?

• Radius/Ulna

• Tibia/Fibula

What 2 structures are most commonly affected with acromelia?

• Hands

• Feet

What 2 structures are most commonly affected with micromelia?

• Entire arm

• Entire leg

With phocomelia, the (1)__________ will be directly attached near the (2)_______.

1. Hands/Feet

2. Trunk

What 2 structures will be missing with amelia?

• Arm

• Leg

The shortening of the proximal segment (humerus/femur) of an extremity will be referred to as…

Rhizomelia

The shortening of the medial segment (radius/ulna, tibia/fibula) of an extremity will be referred to as…

Mesomelia

The shortening of the distal segment (hands/feet) of an extremity will be referred to as…

Acromelia

The shortening of the entire limb will be referred to as…

Micromelia

The absence of a segment of an extremity will be referred to as…

Phocomelia

The absence of an extremity will be referred to as…

Amelia

1. Is this image of the arm normal or abnormal?

2. If abnormal, what pathology is seen here?

1. Normal

2. Normal

1. Is this image of the arm normal or abnormal?

2. If abnormal, what pathology is seen here?

1. Abnormal

2. Rhizomelia

1. Is this image of the arm normal or abnormal?

2. If abnormal, what pathology is seen here?

1. Abnormal

2. Mesomelia

1. Is this image of the arm normal or abnormal?

2. If abnormal, what pathology is seen here?

1. Abnormal

2. Micromelia

1. Is this image of the arms normal or abnormal?

2. If abnormal, what pathology is seen here?

1. Abnormal

2. Phocomelia

What pathology is seen in this image?

Amelia

A small thoracic circumference can indicate ________________ thorax.

Bell-shaped

List the 4 common sonographic features seen in fatal skeletal dysplasias.

• Severe micromelia

• Small thoracic circumference

• Short ribs

• Poor ossification

List the 7 lethal skeletal dysplasias learned in this lecture.

• Thanatophoric dysplasia

• Short-rib polydactyly syndrome

• Homozygous achondraplasia

• Achondrogenesis

• Osteogenesis imperfecta II

• Congenital hypophosphatasia

• Campomelic dysplasia

Short-rib polydactyly syndrome will be ___% lethal.

70%

List the 5 non-lethal skeletal dysplasias learned in this lecture.

• Heterozygous achondroplasia

• Osteogenesis imperfecta I

• Osteogenesis imperfecta III

• Osteogenesis imperfecta IV

• Arthrogryposis

What is the name of the most common lethal skeletal dysplasia?

Thanatophoric Dysplasia

Thanatophoric dysplasia is _________ in occurrence.

Sporadic

List the 5 US findings of Thanatophoric dysplasia.

• Severe micromelia

• Kleeblattschadel (clover leaf skull)

• Platyspondyly

• Narrow thorax with shortened ribs and protuberant abdomen

• Large head with prominent forehead (frontal bossing)

Thanatophoric dysplasia will see severe micromelia, meaning the femur will be shaped how?

Like a telephone

What is another term for kleeblattschadel?

Cloverleaf skull

What is another term for cloverleaf skull?

Kleeblattschadel

Kleeblattschadel (cloverleaf skull) occurs as a result of what other pathology?

Premature craniosynostosis

What does platyspondyly mean?

Flattened vertebral bodies

How does platyspondyly appear on US? (2)

• Flat vertebral bodies

• Increased intervertebral disc space

Which 2 chest shape pathologies can be found with thanatophoric dysplasia?

• Bell shaped

• Champagne cork

What is the medial term for ‘large head with prominent forehead’?

Frontal bossing

1. What is abnormal about this image of the femur?

2. This image can be an US finding of what pathology?

1. ‘Telephone’ shaped (Severe micromelia)

2. Thanatophoric dysplasia

1. What is abnormal about this image?

2. This finding can be associated with what pathology?

1. Micromelia

2. Thanatophoric dysplasia

1. What is abnormal about this image?

2. This finding can be associated with what pathology?

1. Platyspondyly

2. Thanatophoric dysplasia

1. What is abnormal about this image?

2. This finding can be associated with what pathology?

1. Kleeblattschadel (Cloverleaf skull)

2. Thanatophoric dysplasia

1. What is abnormal about this image?

2. This finding can be associated with what pathologies?

1. Bell shaped thorax

2. Thanatophoric dysplasia and Osteogenesis Imperfecta Type 2

1. What is abnormal about this image?

2. This finding can be associated with what pathology?

1. Frontal bossing

2. Thanatophoric dysplasia

1. What is abnormal about this image?

2. This finding can be associated with what pathologies?

1. Kleeblattschadel (Cloverleaf skull)

2. Thanatophoric dysplasia

1. What is abnormal about this image?

2. This finding can be associated with what pathologies?

1. Champagne cork thorax

2. Thanatophoric dysplasia and short rib polydactyly syndrome

Short rib polydactyly syndrome is a __________ skeletal dysplasia.

Lethal

Short rib polydactyly syndrome is characterized by what 4 factors?

• Short ribs

• Narrow thorax

• Short limbs (micromelia)

• Polydactyly

Infants with short rib polydactyly syndrome die due to what pathology?

Pulmonary hypoplasia

List 5 sonographic findings of short rib polydactyly syndrome.

• CNA anomalies

• Cardiovascular system anomalies

• GU tract anomalies

• Face anomalies

• Polyhydramnios

1. What is abnormal about this image?

2. This finding can be associated with what pathology?

1. Short ribs and narrow thorax

2. Short rib polydactyly syndrome

1. What is abnormal about this image?

2. This finding can be associated with what pathology?

1. Polydactyly

2. Short rib polydactyly syndrome

1. What is abnormal about this image?

2. This finding can be associated with what pathology?

1. Short ribs, narrow thorax, and short limbs (micromelia)

2. Short rib polydactyly syndrome

Dwarfism refers to ___________, ______ stature.

• Disproportionately

• Short

Achondroplasia is associated with…

Dwarfism

Achondroplasia produces ________, _______ bones.

• Short

• Squatty

List the 2 types of achondroplasia.

• Heterozygous achondroplasia

• Homozygous achondroplasia

Which form of achondroplasia occurs 80% of the time?

Heterozygous achondroplasia

Which form of achondroplasia occurs 20% of the time?

Homozygous achondroplasia

What is the name of the most common nonlethal skeletal dysplasia?

Heterozygous achondroplasia

Which form of heterozygous achondroplasia has a good survival rate, normal intelligence, and a normal life span?

Heterozygous achondroplasia

Which form of achondroplasia is considered lethal?

Homozygous achondroplasia

What are the 2 sonographic findings of homozygous achondroplasia?

• Severely narrow thorax

• Rhizomelia

Most infants with homozygous achondroplasia will die shortly after birth due to ____________ complications.

Respiratory

List the 4 US findings of achondroplasia.

• Rhizomelia

• Trident hands

• Frontal bossing

• Macrocephaly

Define trident hands.

Increased space between the 3rd and 4th digits

1. What is abnormal about this image?

2. This finding can be associated with what pathology?

1. Trident hands

2. Achondroplasia

1. The femur is at a shortened length in this image. What is that referred to as?

2. This finding can be associated with what pathology?

1. Rhizomelia

2. Achondroplasia

1. What is abnormal about this image?

2. This finding can be associated with what pathologies?

1. Frontal bossing

2. Achondroplasia and thanatophoric dysplasia

Achondrogenesis is a rare, _______ skeletal dysplasia.

Lethal

Infants suffering from achondrogenesis will either be (1)_________ or (2)_____ shortly after birth from (3)_____________________.

1. Stillborn

2. Die

3. Pulmonary hypoplasia

1. What is achondrogenesis caused from?

2. What 2 pathologies will achondrogenesis result in?

1. Cartilage abnormalities

2. Abnormal bone formation and hypomineralization

List the 6 US findings of achondrogenesis.

• Decreased or absent ossification of spine

• Severe micromelia

• Decreased cranial ossification

• Short thorax and short ribs

• Micrognathia

• Polyhydramnios

Define micrognathia.

Abnormally small jaw

Decreased cranial ossification will be seen because the sonographer will be able to ________ the skull.

Compress

1. What is abnormal about this image?

2. This finding can be associated with what pathologies?

1. Decreased or absent ossification of the spine

2. Achondrogenesis

1. What is abnormal about this image?

2. This finding can be associated with what pathologies?

1. Decreased or absent ossification of the spine

2. Achondrogenesis

1. What is abnormal about this image?

2. This finding can be associated with what pathologies?

1. Decreased cranial ossification

2. Achondrogenesis