Ch. 26 The Fetal Spine and Musculoskeletal System Flashcards
The axial skeleton begins to form between the _____ and ______ menstrual weeks. It consists of the bones of the ______and _____.
sixth and eighth; cranium and spine
As bones grow and accumulate minerals, they are said to ossify. It is this ossification that allows sonographers to readily visualize these structures as ________reflections that produce _________. As the pregnancy progresses, the skull and skeletal bones become more echogenic.
echogenic; acoustic shadowing
What 5 sections does the fetal spine cosists of?
cervical, thoracic, lumbar, sacrum, and coccyx
The spine is typically imaged in three scan planes: ______, ______, and ______
sagittal, transverse, and coronal
Each fetal vertebra consists of three echogenic ossification centers: one ______ and two_________.
centrum; neural processes
The centrum will eventually form the ________, whereas the neural process of each vertebra will become the lamina, pedicle, transverse process, spinous process, and articular process.
vertebral body
Between the two laminae and posterior to the centrum lies the _________, the structure that runs the length of the spine and contains the ________.
vertebral column; spinal cord
The echogenic laminae are normally angled ______, whereas with spina bifida, the defective laminae will be angled ______ or be said to ______. The spinal cord appears as a hypoechoic linear structure that extends from the base of the cranium to the distal spine.
inward; outward; splay
embryologic formation that results from fusion of the two folded ends of the neural plate
neural tube
protrusions of intracranial contents through a defect in the skull
cephaloceles
neural tube defect that is described as the absence of the cranium and cerebral hemispheres
anencephaly
_________ and _______ are the most common neural defects, occurring in 1 in every 1,000 pregnancies
Anencephaly and spina bifida
blood screening test that evaluates maternal levels of alpha-fetoprotein, estriol, and human chorionic gonadotropin (as well as other labs) during a pregnancy for neural tube defects and chromosomal abnormalities
maternal serum screening
a maternal blood test that typically includes an analysis of human chorionic gonadotropin, alpha-fetoprotein, and estriol
triple screen
Reportedly, as many as 80% of spina bifida cases can be detected with ________screening in combination with sonography. _____ is initially produced by the yolk sac, fetal gastrointestinal tract, and the fetal liver.
alpha-fetoprotein (AFP)
_____ exits the fetus through an opening in the neural tube if one is present, such as with open spina bifida or anencephaly, thus allowing a greater amount to pass into the maternal circulation.
AFP
It is important to note that an elevation in AFP does ______ necessarily mean that spina bifida is present. _______ MSAFP is also associated with omphalocele, gastroschisis, multiple gestations, and fetal death.
not; Elevated
________ spina bifida is not associated with elevated MSAFP because of the skin covering.
closed
Fortunately, studies have shown that a supplement of just 0.4 mg a day of ________ in a woman’s diet significantly reduces the likelihood of her fetus developing spina bifida and other neural tube defects. In high-risk patients, as much as _____ mg a day may be prescribed.
folate (folic acid); 4
a vitamin that has been shown to significantly reduce the likelihood of a fetus suffering from a neural tube defect; also referred to as folic acid
folate
a group of neural tube defects that describe some manifestation of incomplete closure of the spine
spinal dysraphism
herniation of the cranial or spinal meninges because of an open cranial or spinal defect; contains cerebrospinal fluid, but no nerve tissue
meningocele
mass that results from open spina bifida that contains the spinal cord and the meninges; also referred to as a myelomeningocele
meningomyelocele (myelomeningocele)
closed spinal lesions that are completely covered by skin and can be difficult to identify sonographically; also referred to as closed spina bifida
spina bifida occulta (hidden)
most common form of spina bifida; results in open lesions that are typically not covered by skin and a mass that protrudes from the spine; also referred to as open spina bifida
spina bifida aperta (open)
________ is a neural tube defect that occurs when the embryonic neural tube fails to close. ________may also be referred to as spinal dysraphism, meningocele, and meningomyelocele (myelomeningocele).
Spina bifida
Spina bifida can be subdivided into two types: spina bifida _______ (hidden) and spina bifida _______(open)
occulta; aperta
________ lesions are closed lesions, meaning that they are typically covered by skin and thus can be difficult to identify sonographically in utero. Therefore, with spina bifida _______, although the vertebrae fail to close, there is no herniation of the spinal contents outside the spinal column.
Occult; occulta
-Closed defect
-Skin surface abnormality noted on postnatal physical examination can be a sacral dimple, tuft of hair, hemangioma, or lipoma
Spina bifida occulta
-Typically, an open defect
-May also be referred to as spina bifida cystica
-Mass is referred to as a meningocele or meningomyelocele (myelomeningocele) depending upon contents
Spina bifida aperta
an opening in the skin over the distal spine
sacral dimple
a benign tumor composed of blood vessels
hemangioma
a benign fatty tumor
lipoma
Spina bifida ______, which is an open lesion, is the most common form of spina bifida and the type more frequently recognized in utero. ________ lesions are not covered by skin and will often result in a mass that protrudes beyond the bony defect, making them more readily identifiable with sonography.
aperta; open
If the mass only contains spinal cord, it is referred to as a _______.
myelocele
________contain meninges only, whereas _________ (spina bifida cystic) contain meninges and nerve roots
Meningoceles; meningomyeloceles
The most common location of spina bifida is the _______ region, although it can occur anywhere along the spine. It is also important to note that the higher the location of spina bifida, the _______ the neurologic impairment.
lumbosacral; greater
the sonographic sign associated with a lemon-shaped cranium; most often found in the fetus with spina bifida
“lemon sign”
Spina bifida is often initially recognized by its associated cranial findings, a group of abnormalities referred to as ___________.
Arnold–Chiari II malformation
The pressure of a large mass in the distal spine pulling on the spinal cord causes malformations of the cranium and intracranial contents. The _______ bones become flattened (bifrontal concavity) and will yield a _______-shaped cranium (Fig.26-6). This “_______ sign,” often described as scalloping of the frontal bones, presents a distinct finding on sonography.
frontal; lemon; lemon
posterior portion of the cranium located near the cerebellum and containing the cisterna magna
posterior fossa
the portion of the brain located in the inferior posterior part of the skull that is responsible for motor output, sensory perception, and equilibrium
cerebellum
the sonographic sign of the cerebellum being curved in the presence of spina bifida
“banana sign”
the abnormal lateral ventricle shape in which there is a small frontal horn and enlarged occipital horn
colpocephaly
It is most helpful to analyze the _______ of the cranium for abnormalities when a lemon sign is suspected. The ________ will become displaced inferiorly and posteriorly and appear curved in the presence of spina bifida (gives the “banana sign)
posterior fossa; cerebellum
It is important to note that the fetus with _______ spina bifida will lack these intracranial findings
closed
As a result of the cerebellum being displaced inferiorly (with banana sign), the ________is completely obliterated or nonexistent. The lateral ventricles will also be enlarged and distorted in shape. The frontal horns will be _______ and slit like, whereas the occipital horns will be ______, a condition known as _______.
cisterna magna; small; enlarged; colpocephaly
Keep in mind that spina bifida is associated with two yellow fruits—the _______ and the ________.
banana and lemon
Once cranial findings are suggestive of spina bifida, a thorough analysis of the spine should be performed. In the presence of spina bifida, the posterior ossification elements or laminae will often appear______ in the transverse plane
splayed
A meningocele will appear as a ______cystic mass protruding from the spine, whereas a myelomeningocele tends to appear more _______
simple; complex
Open fetal surgery can be performed on the fetus with spina bifida when a mass is identified on the spine, even as early as ___ weeks. The ultimate goal of this procedure is to prevent, or at least minimize, the _______ deficits associated with spina bifida. During the operation, the uterus, amniotic sac, and fetus are accessed, and the open defect is surgically repaired. After the spinal repair is made, the fetus is placed back into the uterus for continued growth and maturation. In recent years, ______ surgery has presented some promise as a novel approach to fetal spina bifida repair as well.
16; neurologic; fetoscopic
Clinical Findings of Open Spina Bifida Aperta (Open)
Elevated _______
MSAFP
Sonographic Findings of Spina Bifida _________
1.Splaying of the laminae in the area of the defect
2.Cystic mass (meningocele) or complex mass (myelomeningocele) protruding from the spine
3.Lemon sign—lemon-shaped cranium with flattened frontal bones
4..Banana sign—banana-shaped cerebellum
5.Obliterated cisterna magna
6.Colpocephaly
7.Hydrocephalus
Aperta (Open)
Clinical Findings of Spina Bifida ______
1.In utero—normal laboratory values
2.Postnatal—sacral dimple, hemangioma, lipoma, or excessive hair is identified directly over the distal spine
Occulta
Scoliosis is a deformity of the spine in which there is an abnormal ______ curvature. The spine will appear ___shaped in the affected region of scoliosis. Scoliosis typically involves the _____and _______ spine.
lateral; S; thoracic and upper lumbar
Kyphosis is an abnormal _______ curvature of the spine.
posterior
the combonation of both scoliosis and kyphosis in the fetus
kyphoscoliosis
the anomaly of the spine in which there is absence of all or part of a vertebral body and posterior element
hemivertebrae
group of abnormalities associated with the entrapment of fetal parts in the amnion, often resulting in fetal amputations or clefting
amniotic band syndrome
a group of disorders with sonographic findings including a short or absent umbilical cord, ventral wall defects, limb defects, craniofacial defects, and scoliosis
limb–body wall complex (LBWC)