Fetal Spine & Extremities

what are the 5 sections of the spine?

• cervical

• thoracic

• lumbar

• sacral

• coccyx

what are the 3 equidistant ossification centers of the vertebrae?

• one anterior ossification center:

  • vertebral body

• Two posterior ossification centers

  • pedicles and lamina

spinal defects are indicated by?

• asymmetry of the ossification centers

• splaying of the posterior centers

• a break in the overlying skin

most common area of spinal defects?

lumbar region

which scan plane is most diagnostic?

transverse plane

skin and subcutaneous tissues along the posterior fetal back are best visualized in this plane…

LONG

describe US evaluation of the spine in long

• two curvilinear lines extending from the cervical spine to the sacrum

• referred to as the railway sign

• required images are C, T, L, S spine

US evaluation of the spine coronally

• spacing between lines is wider than in sag

• cannot visualize the entire spine in one image due to fetal bedning/arching

• required images are C,T,L,S spine

purpose of fetal extremity exams

to demonstrate and document

• # of extremities

• digits

• contour of extremities

• echoegenicity and shadowing

upper extremity

• upper arm

  • humerus

• forearm

  • radius

  • ulna

• hand

  • digits

lower extremity

• upper leg

  • femur

• lower leg

  • tibia

  • fibula

• foot

  • digits

describe US evaluation of humerus

• long humerus found in sagittal plane-lateral from midline

• shaft and acoustic shadow noted

• cartilaginous head and distal elbow

US evaluation of radius and ulna

• trace humerus to elbow to image radius and ulna

• sag plane splays long axis of each bone

• ulna is longer and located medially

• radius is shorter than ulna and located laterally on thumb

Us evaluation of hands

• count the digits

• is the hand clenched all the time? try to specifically isolate the pinky finger

clenched fist

polydactyl

US evaluation of femur

distal epiphysis seen at the knee by 35 weeks

US evaluation of tibia and fibula

• tibia lie medially and is larger than fibula

• fibula lies laterally

US evaluation of feet

• club foot suspected with abnormal flexion/inversion

• toes should not be visualized with tib/fib