OB 2 Quiz 1 Flashcards
(93 cards)
1
Q
What characterizes macroglossia?
A
Abnormally large tongue extending beyond the lips; tongue remains out regardless of fetal swallowing
* US findings: tongue persistently or repeatedly protrudes beyond fetal lips
* Complication: Polyhydramnios due to impaired swallowing
Associated disorders:
- Beckwith-Wiedemann syndrome
- Acromegaly
- Primary amyloidosis
- Congenital hypothyroidism
- Down syndrome
- Apert syndrome
2
Q
What marks the completion of full facial development?
A
Palate development is complete by the end of the first trimester
3
Q
What is the difference between the soft and hard palate?
A
The soft palate is at the back while the hard palate is the bony part closer to the teeth. Functions of soft palate include aiding speech, swallowing, and breathing.
The soft palate and hard palate form the roof of the mouth.
4
Q
What does the term facial cleft refer to?
A
A wide spectrum of clefting defects usually involving the upper lip, the palate, or both
5
Q
What are the prevalence statistics for facial clefts?
A
- 1 in 700 births
- 50% both lip and palate affected
- 25% only lip affected
- 25% only palate affected
- Unilateral in 75% of cases
- Craniofacial anomalies have constituted approximately 1/3 of all congenital defects
6
Q
What are the anterior cleft palate anomalies?
A
- Upper lip with premaxillary cleft
- Complete unilateral cleft lip
- Complete bilateral cleft lip
7
Q
What are the posterior cleft palate anomalies?
A
- Simple cleft palate
- Unilateral cleft lip and palate
- Complete (bilateral) cleft palate extending to the incisive fossa
8
Q
How are normal orbits characterized in imaging?
A
Reasonable size and equal distance
- Binocular distance is always measured outer canthi of the eyes.
- Interorbital distance is measurement between the orbits.
9
Q
What is cystic hygroma?
A
Benign lymphatic anomaly characterized by cystic areas within the neck’s soft tissues
- Associated with: Chromosomal abnormalities
- Ultrasound: Cystic mass near chest wall or behind fetal head/neck
- May also see ascites, edema, placentomegaly
10
Q
What is myelomeningocele
A
Protrusion of a sac from a spinal defect that contains the spinal cord and meninges
It is the most serious type of spina bifida.
11
Q
Where is the choroid plexus located and what does it do?
A
In the lateral ventricles; it produces cerebrospinal fluid (CSF)
Composed of capillary network, pia mater, and choroid epithelial cells.
12
Q
What structures make up the CNS and how common are CNS abnormalities?
A
- Brain and spinal cord
- 1–2 per 1,000 births (or 1 in 100 by some sources)
13
Q
What is the main role of cerebrospinal fluid (CSF)?
A
Cushions the brain, removes waste, allows the brain to float
14
Q
What is the difference between meningocele and myelomeningocele?
A
- Meningocele: meninges protrude
- Myelomeningocele: spinal cord + meninges protrude (most severe)
15
Q
What are common symptoms of myelomeningocele?
A
Bowel/bladder issues, leg paralysis or sensory loss
16
Q
What is hydrocephalus?
A
Congenital dilatation of the ventricular system.
17
Q
What are the four etiological classifications of hydrocephalus?
A
- Aqueductal stenosis: 43%
- Communicating hydrocephalus: 38%
- Dandy Walker: 12%
- Idiopathic: 7%
18
Q
What are the sonographic findings of hydrocephalus?
A
- Normal ventricle configuration but dilated
- Atrium of lateral ventricle > 10 mm
- Dangling choroid plexus
- Dense brain echogenicity
- Other associated fetal anomalies
19
Q
Differentiate between ventriculomegaly and hydrocephalus.
A
- Ventriculomegaly: refers primarily to ventricle enlargement
- Hydrocephalus: refers to the whole ventricular system’s dilatation due to outflow obstruction.
20
Q
What is hydranencephaly?
A
Total or near total absence of cerebral hemispheres with normal meninges and skull.
- Caused by: Occlusion of the middle cerebral artery (MCA) or internal carotid arteries
- Falx is present (helps distinguish from holoprosencephaly) - THIS IS HYDRANECEPHALY
- Single ventricle or absent/partially present
- No cerebral cortex visible
- Brainstem preserved
Structures typically unaffected:
* Midbrain
* Cerebellum
* Thalami
* Basal ganglia
* Choroid plexus
21
Q
What are associated abnormalities with hydranencephaly?
A
- Renal dysplasia
- Heart defects
- Trisomy 13
- Polyhydramnios
22
Q
What are the sonographic findings of hydranencephaly?
A
- Macrocephaly: Large anechoic area in cranial vault
- Polyhydramnios
- Absent cortical mantle (gray matter)
- Variable presence of 3rd ventricle
- Occasionally small portions of occipital lobes may be seen
- Midbrain, cerebellum, and basal ganglia are intact
- Tentorium separates normal posterior fossa from anterior/middle fossae
- Falx cerebri is present
23
Q
What is holoprosencephaly?
A
Failure of the embryo’s forebrain to divide into two cerebral hemispheres, causing defects in brain structure and function.
24
Q
What is Dandy-Walker malformation?
A
Cerebellar vermian dysgenesis with cystic filling of the posterior fossa. (the VERMIS in the crebellum is MISSING!!!)
Most common congential malformation of the human cerebellum
* 4th ventricle outflow obstruction
* Cerebellar cleft malformation
25
What are associated abnormalities with Dandy-Walker malformation?
* Hydrocephalus
* Other CNS anomalies
* Cardiac anomalies
* Cleft palate
* Meckel-Gruber syndrome
26
What is an Arachnoid Cyst?
A collection of cerebrospinal fluid located towards the back of the brain, covered by pia and arachnoid layers
## Footnote
* We need to **differentiate between a Dandy Walker Malformation or an arachnoid cyst** when in the posterior fossa
* Does not communicate with the ventricles, but rather displaces normal structures of the brain
* Use color doppler and measure
27
Where is an Arachnoid Cyst most commonly located?
Left side of the brain
28
What are common abnormalities associated with hydrocephalus in a fetus?
***CNS abnormalities:***
* Neural tube defects (NTDs)
* Dandy-Walker malformation
* Holoprosencephaly
***Craniofacial anomalies:***
* Cleft lip and/or palate
***Syndromes and genetic conditions:***
* Meckel-Gruber syndrome
* Trisomy 21 (Down syndrome)
* Triploidy
29
What does the "dangling choroid sign" indicate, and how is ventriculomegaly (VM) classified?
* **Dangling choroid sign:** Suggests fetal ventriculomegaly (VM)
* **Normal ventricle measurement:** 5–10 mm (from 15 weeks gestation)
* **Mild VM:** 10–15 mm
* **Severe VM:** >15 mm
30
What are the sonographic findings and associated anomalies of holoprosencephaly?
**Single, midline ventricle** (monoventricle)
**Thin cerebral tissue mantle** surrounding the ventricle
**Craniofacial abnormalities**
* Proboscis
* Cyclopia
* Cleft lip
**Variable appearance depending on severity**
## Footnote
Associated anomolies
* Trisomy 13
* Trisomy 18
* Congenital renal anomalies
* Congenital cardiac anomalies
31
What are the sonographic findings of Dandy-Walker Malformation (DWM)
* Enlarged cystic posterior fossa
* Separated and flattened cerebellar hemispheres
* **Hydrocephalus** in \~25% of cases
* **Polyhydramnios** may be present
* Differentiated from subarachnoid cyst by **continuity with 4th ventricle**
32
What is the difference between Holoprosencephaly and Dandy-Walker Malformation (DWM)?
**Holoprosencephaly**:
* Neuronal migration disorder
* **Failure of the forebrain (prosencephalon)** to divide into two hemispheres
* **Posterior fossa structures are usually normal**
**Dandy-Walker Syndrome (DWS)**:
* Rare congenital malformation of the **cerebellum**
* **Incomplete formation of the cerebellar vermis** (structure joining the two cerebellar hemispheres)
33
What are the sonographic findings and associated anomalies of holoprosencephaly?
**Single, midline ventricle** (monoventricle)
**Thin cerebral tissue mantle** surrounding the ventricle
**Craniofacial abnormalities**
* Proboscis
* Cyclopia
* Cleft lip
**Variable appearance depending on severity**
## Footnote
Associated anomolies
* Trisomy 13
* Trisomy 18
* Congenital renal anomalies
* Congenital cardiac anomalies
34
Facial Anomalies – know these images
**Proboscis and cyclopia**
35
What is the Cavum Septum Pellucidum (CSP), and why is it significant?
* It's a thin membrane connecting the corpus callosum to the columns of the fornix and separating the lateral ventricles
* Its **absence may indicate agenesis of the corpus callosum.**
36
What does absence of the Cavum Septi Pellucidi (CSP) indicate?
Possible agenesis of the corpus callosum
37
Holoprosencephaly - Alobar **(MOST SEVERE)**
38
What defines **semi-lobar** holoprosencephaly?
* Partial fusion of the left and right hemispheres
* Fusion occurs specifically in the **frontal and parietal lobes**
39
What defines lobar holoprosencephaly, the **least severe** form?
* **Two lateral ventricles** are present (right and left)
* **Fusion of the cerebral hemispheres** occurs in the **frontal cortex**
40
What is 'Filly’s Rule'?
If the atrium of the lateral ventricle and the cisterna magna both measure less than 10 mm, there is a 95% negative predictive value for any CNS anomaly.
41
What is hydranencephaly?
Total or near total absence of cerebral hemispheres with normal meninges and skull.
* **Caused by:** Occlusion of the middle cerebral artery (MCA) or internal carotid arteries
* **Falx is present** (helps distinguish from holoprosencephaly) - **THIS IS HYDRANECEPHALY**
* Single ventricle or absent/partially present
* No cerebral cortex visible
* Brainstem preserved
## Footnote
*Structures typically unaffected:*
* Midbrain
* Cerebellum
* Thalami
* Basal ganglia
* Choroid plexus
42
What are the sonographic findings of hydranencephaly?
* Macrocephaly: Large anechoic area in cranial vault
* Polyhydramnios
* Absent cortical mantle (gray matter)
* Variable presence of 3rd ventricle
* Occasionally small portions of occipital lobes may be seen
* **Midbrain, cerebellum, and basal ganglia are intact**
* **Tentorium** separates normal posterior fossa from anterior/middle fossae
* **Falx cerebri is present**
43
What is Dandy-Walker malformation?
Cerebellar vermian dysgenesis with cystic filling of the posterior fossa. **(the VERMIS in the crebellum is MISSING!!!)**
## Footnote
Most common congential malformation of the human cerebellum
* 4th ventricle outflow obstruction
* Cerebellar cleft malformation
44
What does a normal sagittal view of the fetal head at 22 weeks show in relation to aqueductal stenosis evaluation?
* **Cavum veli interpositi:** Located posterior and inferior to the CSP
* **Fourth ventricle:** Visible as a distinct structure
* **Cisterna magna:** Identified by an open arrow
* **Cerebellum:** Labeled as “c” in imaging
* These structures help distinguish normal anatomy from aqueductal stenosis, where obstruction occurs at the Aqueduct of Sylvius.
45
What is the difference between Holoprosencephaly and Dandy-Walker Malformation (DWM)?
**Holoprosencephaly**:
* Neuronal migration disorder
* **Failure of the forebrain (prosencephalon)** to divide into two hemispheres
* **Posterior fossa structures are usually normal**
**Dandy-Walker Syndrome (DWS)**:
* Rare congenital malformation of the **cerebellum**
* **Incomplete formation of the cerebellar vermis** (structure joining the two cerebellar hemispheres)
46
How does Cisterna magna appear?
CSF-filled, appears anechoic
47
What key structures are located in the midbrain region of the fetal brain?
* Cerebral peduncles
* Corpora quadrigemina
* The 4th ventricle.
48
What structures make up the hindbrain in fetal brain development?
The pons, cerebellum, and medulla oblongata.
## Footnote
Openings in the subarachnoid space filled with CSF
**Cisterna magna appears anechoic**
49
Hindbrain continued... image identification
* 1 = Cervical Spinal Cord
* 2 = Medulla Oblongata
* 3 = Pons
* 4 = Cerebellum
* 5 = Cisterna magna
50
What are the sonographic findings for spina bifida?
* **Transverse Spine:** splaying of posterior ossification centers
* **Sagittal Spine:** discontinuity of parallel lateral ossification centers
* **Intracranial:** lemon sign and banana sign
51
What does the Circle of Willis do?
Allows for proper blood flow from the arteries to both the front and back hemispheres of the brain
(The arteries that stem off from the **circle of Willis** supply much of the blood to the brain)
## Footnote
Important for preventing neurological deficits in case of arterial occlusion.
52
By what week are spinal ossification centers visible?
By 16 weeks gestation
53
List the five embryonic brain vesicles?
**Forebrain:** Telencephalon and Diencephalon
**Midbrain:** Mesencephalon
**Hindbrain:** Metencephalon and Myelencephalon
## Footnote
These structures evolve from the primary vesicles.
54
List the three primary vesicles formed after the closure of the rostral neuropore
* Prosencephalon (forebrain)
* Mesencephalon (midbrain)
* Rhombencephalon (hindbrain)
55
What brain structures develop from the Prosencephalon?
Cerebral hemispheres, lateral ventricles, thalamus
56
What brain structures develop from the Mesencephalon?
cerebral peduncles, corpora quadrigemina
57
What brain structures develop from the Rhombencephalon?
pons, cerebellum, medulla
58
What is spina bifida?
A defect in the spinal column resulting from failure of neural tube closure
59
What characterizes spina bifida occulta **(hidden)**
* Mildest form
* Defect in the **posterior bony arch**
* **Skin and tissue remain intact**
* Often causes **no symptoms**
60
What characterizes spina bifida aperta?
* Visible opening along the spine
* Allows **herniation of neural tissue**
Types include:
* **Myelocele**: Herniation of **meninges only**
* **Myelomeningocele**: Herniation of **meninges and neural tissue**
* **Rachischisis**: **Complete opening** of the spinal canal (most severe form)
**Associated condition**: **Tethered cord** (spinal cord abnormally attached)
61
What is rachischisis?
* Also known as **complete spina bifida**
* **Severe form** of spina bifida with a **cleft through the entire spine**
* Involves the **entire neural tube**, from cervical spine to sacrum
Commonly associated with **cranial neural tube defects** such as:
* **Anencephaly**
* **Acrania**
* **Iniencephaly**
* **Almost always fatal**
62
What are common signs of spina bifida occulta?
* Tuft of hair on the lower back
* Dimple on the lower back
63
What is a tethered cord?
A spinal cord that can't move freely inside the spinal canal
64
What is the Chiari II malformation?
Condition in which brain tissue extends into the spinal canal, present at birth
65
What is anencephaly?
* **Absence of the cranial vault and cerebral hemispheres**
* **Most common neural tube defect**
* Portions of the **midbrain and brainstem may be present**
*Associated facial features:*
**Microphthalmia**: Small eyes
**Macroglossia**: Large tongue
**Severely shortened neck**
66
What are the epidemiological and clinical characteristics of anencephaly?
* **Most common neural tube defect**
* Incidence: ~1 in 1,000 pregnancies in the U.S.
More common in:
**Females (4:1)**
**Caucasians vs. African-Americans (6:1)**
**Caused by:** Failure of cranial end of neural tube to close
**Recurrence risk:** 2–3% if prior pregnancy had an open NTD
**Prognosis:**
Up to **50% end in fetal demise**
Most of the remainder **die at birth or shortly after**
**Diagnosis:** Often made prenatally via ultrasound, especially after **elevated maternal serum AFP levels**
67
What is an encephalocele and how does it differ from a cephalocele?
* **Encephalocele:** Herniation of meninges and brain tissue through a skull defect due to incomplete neural tube closure
* **Cephalocele:** Herniation of meninges only
* **Most common location:** Occipital region (back of the head)
*Associated conditions:*
**Spina bifida** (7–15% of cases)
**Hydrocephalus** (in ~80% of cases)
68
What is Meckel-Gruber syndrome?
Lethal autosomal recessive condition
**Classic triad:**
* Occipital encephalocele
* Large polycystic kidneys
* Postaxial polydactyly
**Associated abnormalities:**
* Oral clefting
* Genital anomalies
**CNS malformations:**
* Dandy-Walker malformation
* Arnold-Chiari malformation
Liver fibrosis
Pulmonary hypoplasia (most common cause of death)
69
What is iniencephaly?
A rare neural tube defect characterized by exaggerated spinal lordosi, cervical rachischisis, and occipital encephalocele
70
What are the associated anomalies and sonographic findings of iniencephaly?
**Associad anomalies:**
* Anencephaly
* Diaphragmatic hernia
* Pulmonary hypoplasia
* Cardiac defects
**Sonographic findings:**
* Exaggerated cervical lordosis “stargazer”
* Occipital bone defects
* Short fused cervical vertebrae
* Polyhydramnios
71
What is craniorachischisis?
Completely open brain and spinal cord
72
What are common associated abnormalities with spina bifida?
* Trisomy 18
* Trisomy 13
* Chiari II malformation
* Hydrocephalus
* Clubfoot
* Rocker bottom foot
73
What are some sonographic findings associated with spina bifida?
* Lemon sign
* Banana sign
74
What anomalies are commonly associated with encephalocele?
* Meckel-Gruber syndrome
* Agenesis of the corpus callosum
* Orofacial clefting
* Dandy-Walker malformation
* Arnold-Chiari malformation
* Iniencephaly
* Hydrocephalus
* Polyhydramnios
**Note**: Encephaloceles may be **isolated**, but **23% to 37.5%** are associated with other **CNS, extra-CNS anomalies**, or **genetic syndromes**, especially **Meckel-Gruber syndrome**.
75
What are the three facial prominences that begin to evolve by 6 menstrual weeks?
Frontonasal, Maxillary, Mandibular
76
At what menstrual weeks does the bony structure of the face begin to form?
6-7 menstrual weeks
77
When does ossification of the mandible, maxilla, and orbits begin?
8-9 menstrual weeks
78
At what stage can sonographically see the bony structures of the face?
11-12 menstrual weeks
79
By what menstrual weeks is the face well defined?
14-16 menstrual weeks
80
What structures develop by the 12th menstrual week?
* Pharyngeal arches and grooves into face, nasal cavities, mouth, tongue, larynx, pharynx, neck fascia
* Salivary and thyroid glands
* Skeletal, neural, muscular and vascular neck structures
* Somites into muscle, cartilage, tendons endothelial cells, dermis
81
What can be consistently identified from 12 weeks of gestation during a sono exam?
* Forehead
* Orbits
* Nose
* Lips
* Ears
82
What is a neuropore?
Either the rostral or caudal end of the neural tube
## Footnote
Important in the process of neurulation.
83
What is neurulation?
The process by which the neural tube is formed
## Footnote
Critical for proper CNS development.
84
What are the stages of neurulation?
* Neural plate
* Neural groove
* Neural folds
* Neural tube final stage
## Footnote
These stages are essential for CNS development.
85
What happens during the fusion of the neural tube?
Begins in the mid-portion of the embryo and proceeds rostrally and caudally
## Footnote
The rostral end closes on Day 25 and the caudal end on Day 27.
86
What are the closure days for the rostral and caudal neuropores?
Rostral: Day 25, Caudal: Day 27
87
What happens if the neural tube fails to close?
Neural Tube Defects (NTDs) occur
88
Where is the choroid plexus located and what does it do?
In the lateral ventricles; it produces cerebrospinal fluid (CSF)
## Footnote
Composed of capillary network, pia mater, and choroid epithelial cells.
89
What is the Diencephalon?
Located between the cerebrum and midbrain, consists of thalamus ("interbrain") and hypothalamus
## Footnote
The Diencephalon plays a key role in sensory and regulatory functions.
90
What is the function of the corpus callosum?
Large bundle of 200+ million myelinated nerve fibers that connects the left and right cerebral hemispheres.
91
What is considered an abnormal measurement for the lateral ventricles?
Greater than 10 mm
## Footnote
Normal is <7mm
92
When is the third ventricle typically visible on ultrasound?
When dilated due to conditions like **hydrocephalus**
93
What key structures are located in the midbrain region of the fetal brain?
* Cerebral peduncles
* Corpora quadrigemina
* The 4th ventricle.
