Diagnostic ultrasound ( PDFDrive )

1220 PART IV Obstetric and Fetal Sonography
S
S
T
L
T
L
P
P
C
C
A
B
5 mm
FIG. 35.4 Vertebral Ossiication of T9 at 16 Weeks’ Gestation. (A) Specimen. (B) Radiograph. Ossiication extends quite far into the pedicles
(P) and laminae (L). Note the early ossiication in the base of the transverse processes (T). The width of the vertebra is about 5 mm. There is ossiication
within the centrum (C). S, Spinous process (cartilage); T, transverse process (cartilage). The distance between the arrowheads is 5 mm.
L
L
P
P
C
C
A
B
FIG. 35.5 Vertebral Ossiication of L5 at 17 Weeks’ Gestation. (A) Specimen. (B) Radiograph. There is usually enough ossiication at this
gestation in the pedicles (P) and laminae (L) to determine the true course of these structures in radiographs and sonograms. The width of the
vertebra is about 5 mm. There is ossiication within the centrum (C).
TABLE 35.2 Timing and Pattern of Fetal Spine Ossiication (10-22 Weeks’ Menstrual/
Gestational Age)
Age (Wk)
Events
10 Ossiication appears in lower thoracic spine vertebral bodies.
13 Some ossiication is present from C1 to L5 vertebral bodies and arches.
13-22 Neural arch ossiication simultaneously extends anteriorly into the pedicles and posteriorly into the laminae.
16 Enough neural arch ossiication appears to assess for spina biida to level L5.
19 Enough neural arch ossiication appears to assess for spina biida to level S1.
22 Enough neural arch ossiication appears to assess for spina biida to level S2.