The Fetal Ultrasound Assessment of Fetal Skeletal System Skeletal System  Extremities  Spine  Calvarium

Carol B. Benson, MD No Disclosures

Extremities

Assess To Exclude Calderon Femur length Size Skeletal dysplasia Presence Absent limb Amniotic band syndrome Bones of forearms Radial hypoplasia Hand position Clenched fists Foot position Clubfoot Rockerbottom foot

Michel arm 3 bones

Caraballo nl hand Femur Length

Foot Normal for gestational age = Mean ± 2 SD Femur length falls 2 - 4 SD below mean Most are growth restricted Without skeletal dysplasia Femur length falls > 4 SD below mean Usually a skeletal dysplasia Bones appear abnormal by US

Steimle Femur length Long Bones are Too Short

 Skeletal dysplasia  Dysotosis  Malformation  Deformation amniotic band syndrome restrictive uterine environment

Lethal Skeletal Dysplasias Nonlethal Skeletal Dysplasias Neonate cannot survive Infants typically survive usually due to respiratory failure Ultrasound diagnosis typically Ultrasound diagnosis typically not made in 2nd trimester made in 2nd trimester sometimes made in 3rd trimester  Thanatophoric dysplasia  Heterozygous achondroplasia  Osteogenesis imperfecta Type 2  Osteogenesis imperfecta Types 1&4  Achondrogenesis  Asphyxiating thoracic dystrophy  Congenital hypophosphatasia  Short rib – polydactyly syndrome Skeletal Dysplasias Thanatophoric Dwarf

Ultrasound assessment Most common lethal skeletal dysplasia Degree of shortening of long bones Severe rhizomelia typically > 4 SD below mean for GA (proximal shortening) Distribution of involved bones Bowed long bones extremities, spine, calvarium, ribs Narrowed thorax – short ribs Bony abnormalities Flattened vertebral bodies ↓ mineralization, fractures, bowing Cloverleaf skull Polydactyly Megalencephaly – temporal lobe with excess sulcation/fissures

Thanatophoric dysplasia

Kristian 19w thanatophoric

Kristian 19w thanatophoric

FEM

Osteogenesis Imperfecta Osteogenesis Imperfecta Type 2 Type 2

Type 2 — Autosomal recessive Lethal Ultrasound findings — Type 2 Lopez OI Fractures Deformities Poor mineralization Soft skull Types 1, 3, & 4 — Autosomal dominant Nonlethal Osteogenesis Imperfecta Type 2 Osteogenesis Imperfecta Type 2

Lopez OI Astacio OI 3D

Osteogenesis Imperfecta Osteogenesis Imperfecta Type 1 Type 1 & 4 Type 1 & 4 — Autosomal dominant Nonlethal Ultrasound findings — Type 1 & 4 McBride OI type 4 Lagging growth of long bones 3rd trimester Bowing of long bones Mild deformities Poor mineralization Soft skull

Osteogenesis Imperfecta Type 4 Osteogenesis Imperfecta Type 4

Jones fem fx Al-Owfi OI type 4 OI 4

2.4 cm 2.0 cm

18 weeks Arthrogryposis Arthrogryposis Multiplex Congenita

Multiple joint contractures Etiologies Ultrasound findings  Limitation to movement Contractures Oligohydramnios Fetal growth restriction Multiple gestation Polyhydramnios Bicornuate uterus Hydrops  Abnormal nerve function  Abnormal musculature  Defective connective tissue

Arthrogryposis

Eires arthrogryposis

Beausoleil arthrogryposis

Arthrogryposis from Larsen syndrome (rare genetic syndrome) McGuigan arthrogryposis

Banerjee Larsen syn arthrogryposis Abnormal Hands & Forearms Radial Ray Anomalies Associated with Inherently abnormal Malformation Syndromes Dysplasia Cornelia de Lange Fanconi anemia Normal tissues effected by external Holt-Oram factors Radial aplasia-Thrombocytopenia Deformation Poland syndrome uterine constraints Nager acrofacial dysostosis amniotic band syndrome VACTERL Disruption (e.g., teratogen) Trisomies 13 & 18

Radial Ray Defect Abnormal Thumb Hypoplastic radius VACTERL Abnormal thumb VACTERL

Martins hypopl Henebry VACTERL radius VACTERL abnl thumb

Absent radius Limb Reduction Defects

Terminal transverse deletions (e.g., absent hands) Landry absent radius tri 18 Isolated sporadic, unilateral amniotic band syndrome vascular accident Syndromes Orofacial (e.g., Poland) Amniotic bands Penney absent toes ABS Osgood absent hand

Nager Acrofacial Dysostosis

Characteristics

Osgood absent Mandibulofacial dysostosis hand 3D bones Hypoplastic mandible External ear abnormalities ± Auditory canal atresia Upper extremity reduction defects Radial ray defects

Polydactyly Supernumerary fingers or toes Skeletal dysplasias Alshamsi Nager’s Short-rib polydactyly Chondroectodermal dysplasia Asphyxiating thoracic dysplasia Trisomy 13 Meckel-Gruber syndrome Autosomal dominant polydactyly usually post-axial Polydactyly with Meckel-Gruber Polydactyly

MacGowan polydactyly with Isabelle Meckel Gruber Polydactyly

Hand Foot 13 weeks 17 weeks

Polydactyly Ectrodactyly

V-shaped defect (cleft) in middle of hands &/or feet with missing digits Torres ± Syndactyly Polydactyly 25 weeks Associated Genetic syndromes, e.g. Split-hand-foot malformation Silver-Russell 19 weeks Cornelia de Lange

Dowd ectrodact hands & feet Ligibel cleft hand missing finger

Appleton absent finger

Cleft hand Clinodactyly Clinodactyly & short Overlapping Digits middle phalanx Deviation or deflection of finger(s) Subenko clinodactyly Curving of 5th finger towards 4th Trisomy 21 Overlapping digits Normal Trisomy 13 Trisomy 18

Clenched hands – Trisomy 18

Sin abnl hands

Dixon clinodactyly

Clubfoot Clubfoot Etiology Genetic Lashley clubfeet A variety of syndromes Chromosomal defects 13 weeks Environmental Severe oligohydramnios Uterine anomalies Ultrasound findings Bones of the foot lie in parallel to bones of lower leg 21 weeks Rockerbottom feet – Trisomy 18 Rockerbottom Foot

Etiology Woodland Trisomy 18 rockerbottom feet Skeletal dysplasia Ultrasound findings Rounded bottom of foot

Rockerbottom feet Amniotic Band Syndrome Early rupture of amnion

Atlas BRB rockerbottom feet  Fibrous bands entrap or adhere to fetus  Limb amputations or deformities Encephaloceles Facial clefts Ventral wall defects Ectopia cordis

Amniotic Band Syndrome Amniotic Band Syndrome Ultrasound Findings Fetal deformities Dailey ABS Skeletal anomalous hand Craniofacial Ventral wall Adherent bands

DDx: Amniotic “sheets” Amniotic Band Syndrome Spinal Abnormalities

 Meningomyelocele Juris ABS missing hand  Hemivertebra 13 weeks  Scoliosis  Diastomatomyelia  Caudal regression / sacral agenesis  Sacrococcygeal teratoma 21 weeks

Meningomyelocele

Guilmet Meningomyelocele

Normal

Meningomyelocele

Meningocele

Bardales tri 18 Meningomyelocele Spina bifida Protrusion of membranes & fluid No protrusion of nerve roots Often skin covered Ultrasound findings splaying of posterior elements cystic mass protruding 19 weeks

Reif 20w Cabral 19w 3D Meningocele Meningocele

Hemivertebrae Hemivertebrae

Associated with a variety of syndromes Johnson hemivertebrae Ultrasound findings Kink in spine Mismatch of posterior ossification centers

Hemivertebrae

1

5 Rossman hemivert Hazen Hemivert 10

13 Sacral agenesis Sacral Agenesis

MacDougall  Hypoplasia / absence sacral agen 2 or more sacral vertebrae  In fetuses of diabetic mothers with poor glucose control

Sacral agenesis Caudal Regression

Benson sacral agenesis  Sacral agenesis + Anomalies of pelvis and lower extremities  In fetuses of diabetic mothers with poor glucose control

Caudal regression Sacrococcygeal Teratoma

Germ cell tumor arising Kelshan caudal regression in presacral area Ultrasound findings Mass arising from lower sacrum Extending posteriorly and inferiorly ± Hydrops ± Extension anteriorly into pelvis Sacrococcygeal Teratoma Sacral erosion Cranial Anomalies

 Craniosynostosis Bonica SCT  Trigonocephaly (Trisomy 13)  Cloverleaf skull (Thanatophoric dysplasia)  Lemon sign (Chiari II malformation)  Strawberry skull (Trisomy 18)

Craniosynostosis Craniosynostosis Premature closure of one or more cranial sutures; Male:Female = 2:1 Complications: Abnormal head shape Harrigan craniosyn Abnormal faces Neurologic deficits e.g., hearing loss Prenatal diagnosis Typically not possible before 3rd trimester 26 weeks

Trigonocephaly – Trisomy 13 Trigonocephaly

Craniosynostosis with premature

Britt tri 13 fusion of metopic suture trigonoceph (anterior midline, forehead) Associated with Trisomy 13

Semilobar 35 weeks Holoprosencephaly Cloverleaf skull – Thanatophoric dysplasia Cloverleaf Skull

Craniosynostosis causing trilobed shape Cole thanat skull prominent forehead Associated with Thanatophoric dysplasia

37 weeks

Lemon-Shaped Cranium Nogueria lemon sign Associated with Chiari II malformation Meningomyelocele

Lemon Sign with Meningomyelocele

Strawberry-Shaped Cranium Strawberry-Shaped Cranium Trisomy 18 – 15 weeks

Associated with Trisomy 18 Schindler strawb sk