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)
an acronym for a combination of abnormalities that represent vertebral anomalies, anorectal atresia, cardiac anomalies, tracheoesophageal fistula, renal anomalies, and limb anomalies; may also be referred to as VATER association
VACTERL association
Sonographic Appearance of ______
Lateral curvature of the spine
S-shaped spine
Scoliosis
Sonographic Appearance of _______
Abnormal posterior curvature of the spine
Kyphosis
form of acrania in which the entire cerebrum is located outside the skull
exencephaly
protrusion of brain tissue through a defect in the skull
encephalocele
LBWC, also referred to as _______ or ________, is a rare group of fetal defects. There are three postulated causes for this fatal condition: vascular occlusion, amnion rupture, or embryonic dysgenesis.
body stalk anomaly; short umbilical cord syndrome
The most common sonographic findings of LBWC are a ______ or ______ umbilical cord, ventral wall defects, limb defects, craniofacial defects (exencephaly or encephalocele), and scoliosis. The fetus will appear closely connected with the _______ and will have marked scoliosis
short or absent; placenta
________ has very similar sonographic findings and may actually be seen simultaneously with LBWC.
Amniotic band syndrome
Clinical Findings of Limb–Body Wall Complex
Elevated _______
MSAFP
Sonographic Findings of ________
1.Short or absent umbilical cord
2.Marked scoliosis
3.Various other anomalies including craniofacial and limb defects
Limb–Body Wall Complex
the abnormal development of a structure
dysplasia
________ denotes the abnormal development of a structure. _______ dysplasias exist as a large group of abnormalities of the skeletal system. More than 271 skeletal dysplasias have been identified.
Dysplasia; Skeletal
a disorder that results in abnormal bone growth and dwarfism
achondroplasia
most common nonlethal skeletal dysplasia that is characterized by rhizomelia
heterozygous achondroplasia
shortening of the proximal segment of a limb
rhizomelia
a way in which a disorder or trait can be inherited by a fetus; at least one of the parents has to be the carrier of the gene for the disease
autosomal dominant disorder
the fatal form of achondroplasia
homozygous achondroplasia
the angling of the frontal bones that produces an unusually prominent forehead
frontal bossing
a wide separation between the middle and ring finger
trident hand
________ is the most common nonlethal skeletal dysplasia. This is a type of ______ in which the proximal portions of the limbs, the humeri and femurs, are much shorter than the distal portion of the limbs, a condition known as _________.
Heterozygous achondroplasia; dwarfism; rhizomelia
Heterozygous achondroplasia is an __________, although, many times, it is the result of a spontaneous genetic mutation.
autosomal dominant disorder
Rhizomelia is typically detected when a notable difference in the gestational age measurements between the ________and the _______ is discovered, typically in the mid to late second trimester.
biparietal diameter; femur length
_________, which can occur when both parents are dwarfs, is usually fatal within the first 2 years of life.
Homozygous achondroplasia
Sonographic Findings of _________
1.Macrocrania
2.Frontal bossing
3.Flattened nasal bridge
4.Micromelia (resulting from rhizomelia)
5.Trident hand
Achondroplasia
_________ is a rare, lethal condition, resulting in absent mineralization of the skeletal bones. The term _________ is interpreted “not producing cartilage.” There are three types of __________—type 1A, type 1B, and type 2.
Achondrogenesis
rare, lethal condition resulting in abnormal development of the bones and cartilage
Achondrogenesis
Sonographic Findings of ________
1.Severely shortened limbs (micromelia)
2.Absent mineralization of the skull, spine, pelvis, and limbs
3.Large skull
4.Narrow chest and distended abdomen
5.Polyhydramnios
*may have rib fractures
Achondrogenesis
_________, commonly known as brittle bone disease, is a group of disorders that results in multiple fractures that can occur in utero.The fractures are a result of decreased mineralization and poor ossification
Osteogenesis imperfecta
Sonographic Findings of _______
1.Demineralization of the skull (transducer pressure can alter the shape of the skull)
2.Multiple fractures
3.Bell-shaped chest
Osteogenesis Imperfecta
There are ______ different types of osteogenesis imperfecta. Type ____, a uniformly fatal form of osteogenesis imperfecta, is the most severe type of the disease.Types I, III, and IV are typically diagnosed ______ birth.
four, II, after
Osteogenesis imperfecta type II results in multiple fractures in utero, skull demineralization (recognized by a lack of posterior shadowing), _______chest, and ________ fetal movement.
bell-shaped; decreased
_________ (“death-bearing”) dysplasia is the most common lethal skeletal dysplasia.
Thanatophoric
The fetus with thanatophoric dysplasia will have a ___________ with frontal bossing and hydrocephalus
cloverleaf skull
In addition with thanatophoric dysplasia, the shortened long bones take on a “_________” shape, because the diaphysis of the long bones will be ______ and have _______ metaphyseal ends
telephone receiver;bowed; prominent
the abnormal shape of the cranium caused by premature fusion of the sutures in which there is frontal bossing and a cloverleaf shape to the skull
cloverleaf skull
The thoracic and abdominal circumference will be remarkably dissimilar in thanatophoric dysplasia, leading to a bell-shaped chest. Specifically, the thorax will be remarkably narrow, resulting in _______ of the ______, whereas the abdomen will appear prominent. This disparity can be best recognized with a sagittal image of the fetus. To document that the chest is much smaller than the abdomen, a _______ circumference measurement can be obtained.
hypoplasia of the lungs; thoracic
Sonographic Findings of _______
1.Cloverleaf skull
2.Hydrocephalus
3.Depressed nasal bridge
4.Bell-shaped chest (narrow thorax)
5.Polyhydramnios
6.Redundant soft tissue (especially on the limbs)
7.Telephone receiver–shaped long bones
Thanatophoric Dysplasia
Fetuses with thanatophoric dysplasia typically die shortly after birth, succumbing most often to respiratory distress as a result of ________.
pulmonary hypoplasia
Caudal regression syndrome may also be referred to as ________
sacral agenesis
Maternal diabetes that existed before pregnancy; includes both type 1 and 2 diabetes mellitus
pregestational diabetes
The nondevelopment of the sacrum
sacral agenesis
syndrome associated with the absence of the sacrum and coccyx; also referred to as sacral agenesis
Caudal regression syndrome
Clinical Findings of Caudal Regression Syndrome
Uncontrolled maternal ___________
pregestational diabetes
Sonographic Findings of ________
1.Absent sacrum (sacral agenesis) and possibly part of the lumbar vertebra (abrupt ending of the spinal cord)
2.Possible abnormalities in the lower extremities like clubfeet
Caudal Regression Syndrome
The sonographic findings of caudal regression syndrome are absence of the ________ and ________
sacrum (sacral agenesis) and coccyx (coccygeal agenesis)
______ is also referred to as mermaid syndrome because of the fusion of the lower extremities that occurs with this disorder.
Sirenomelia
With Sirenomelia bilateral renal agenesis often accompanies this condition, it is almost always lethal. In turn, _________ and many other defects, including cardiac anomalies, genital absence, and a two-vessel cord, may be seen.
oligohydramnios
Clinical Findings of Sirenomelia
Uncontrolled __________
pregestational maternal diabetes
Sonographic Findings of ________
1.Fusion of the lower extremities
2.Bilateral renal agenesis
3.Oligohydramnios (possibly anhydramnios
Sirenomelia
a lower-than-normal amount of amniotic fluid for the gestational age
oligohydramnios
a type of neoplasm derived from germ cells of the gonads; may also be found outside the reproductive tract
germ cell tumor
the dilation of the renal collecting system resulting from the obstruction of the flow of urine from the kidney(s) to the bladder; also referred to as pelvocaliectasis or pelvicaliectasis
Hydronephrosis
includes the bones of the upper extremities, lower extremities, and pelvic girdle
appendicular skeleton
An SCT is a __________. This means that this mass contains elements of the three different germ cell layers: endoderm, mesoderm, and ectoderm.
germ cell tumor
_____________has been cited as the most common congenital neoplasm and is more frequently found in females. This tumor will typically appear as a complex or solid mass extending posteriorly and inferiorly from the distal fetal spine
Sacrococcygeal teratoma (SCT)
Sonographic Findings of __________
1.Complex mass extending from the distal fetal spine
2.Mass can be highly vascular
3.Hydronephrosis may be present (when mass invades the pelvis)
4.Fetal hydrops may be present
5.Cardiomegaly
*may lead to high-output congestive heart failure
Sacrococcygeal Teratoma
An SCT has the potential to grow inside the ______ and may cause obstruction of the urinary tract and destruction of the sacrum and pelvic bones. Large SCTs have ________ potential.
pelvis, malignant
the appendicular skeleton begins to form between the ______ and ______menstrual weeks. The ___________ includes the bones of the upper extremities, lower extremities, and pelvic girdle.
sixth and eighth; appendicular skeleton
The first sonographic appearances of the fetal limbs are referred to as ______. During the second trimester, the fetal limb bones take on more of an adult appearance and appear ______and will produce posterior shadowing.
limb buds; echogenic
The _______extremities include the phalanges (fingers), the metacarpals, carpals, radius, ulna, humerus, clavicle, and scapula. The________extremities consist of the phalanges (toes), metatarsals, tarsals, tibia, fibula, and femur
upper; lower
The tibia and fibula end at the same distal location. The tibia is the _______ of the two bones, and it is more medial in location.
larger
In the forearm, the ulna is _______ proximally compared to the radius and is associated with the side of the fifth digit (smallest finger). Thus, in the anatomic position, the radius is located _______ and associated with the _______.
longer; laterally; thumb
The sonographic determination of the shortening of a limb is made when the long bones measure more than _______ standard deviations below the norm for gestational age.
four
_________ is uncommon and described as the absence (aplasia) or underdevelopment (hypoplasia) of the radius. This abnormality can be seen in the presence of trisomy 13, trisomy 18, and several other syndrom.
Radial ray defect
Sonographic Findings of ________
1.Absent or hypoplastic radius
2.Various defects in other body systems: cardiac, possibly a clubhand (talipomanus), and VACTERL association
Radial Ray Defect
Clubfoot, also referred to as talipes or _________, is a malformation of the bones of the foot. The foot is most often inverted and rotated medially. The sonographic diagnosis of clubfoot can be made when the ______ and ____ lie in the same plane as the tibia and fibula.
talipes equinovarus; metatarsals and toes
If an abnormal foot shape is suspected, a ________measurement can be obtained by measuring from the skin edge of the heel (calcaneus) to the distal end of the longest toe.
foot length
Foot length has been used for gestational dating as well, and it has been shown to be nearly equivalent to the _______, resulting in a femur-to-foot ratio of approximately ______ after 14 weeks’ gestation.
femur length, 1.0
Sonographic Findings of _______
Metatarsals and toes lie in the same plane as the tibia and fibula
Clubfoot
Limb reduction can be caused by amniotic band syndrome, also referred to as _________. Sticky bands result from the rupture of the ______. These bands can entrap fetal parts and cause amputation of digits, limbs, and even the skull. Amniotic bands can also lead to peculiar _________clefting.
amniotic band sequence; amnion; facial
amniotic bands should not be confused with uterine ________. Amniotic bands may be seen with sonography, though, occasionally, only the results of the bands are seen. Uterine ________may be recognized as linear, thin membranes with a_________ base crossing the amniotic sac
synechiae, synechiae, broad
Sonographic Findings of _________
1.Amputation of fetal parts or severe edema in the affected area
2.Thin, linear bands may be seen
3.Facial clefting
Amniotic Band Syndrome
The thalamic tissue located within the third ventricle of the brain that can become enlarged with Arnold-Chiari II malformation is the:
a. corpus callosum
b. cerebellar vermis
c. cavum septum pellucidum
d. massa intermedia
d. massa intermedia
the brain and spinal cord are covered by what?
meninges
Absent hand
Acheiria
Shortening of the distal segment of a limb
Acromelia
Absent limb
Amelia
Absent foot
Apodia
Limitation of fetal limb motion as a result of joint contractures; most often affecting the hands and feet
Arthrogryposis
Deviation of a finger (e.g., absence of the middle fifth phalanx)
Clinodactyly
Absent part of an extremity distal to the elbow or knee
Hemimelia
Shortening of the middle segment of a limb
Mesomelia
Shortening of an entire limb
Micromelia
Having less than the normal number of digits
Oligodactyly
Absent long bones with the hands and feet arising from the shoulders and hips
Phocomelia
Having more than the normal number of digits
Polydactyly
Abnormal curved shape of the sole of the foot
Rocker-bottom foot
Exaggerated distance between the first toe and the second toe
Sandal gap
Fusion of digits (e.g., webbed toes)
Syndactyly
Clubhand
Talipomanus
Increases space between the third finger and the fourth finger
Trident hand
