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.