OB: second/third trimester - boards review
amniocentesis detects what (3)
- Chromosome abnormalities: Down syndrome/ trisomy 21 = most common chromosome abnormality. - Neural tube defects (high AFP): Most common is spina bifida - Genetic disorders: Cystic fibrosis
brain - nuchal skin fold: measured in same plane as what other structures normal size increased means what usually
- Measured in plane containing cavum septum pellucidi, cerebellum and cisterna magna - 5mm or less up to 20 week is normal (*should be less than 3 mm?) - Thickened = risk for aneuploidy
roles of amniotic fluid (7)
- PROTECTS from injury - CUSHIONS - Allow for fetal MOVEMENT - PREVENT ADHERENCE of amnion to embryo - Allow for SYMMETRICAL GROWTH - Maintain CONSTANT TEMP - RESERVIOR for fetal metabolites
4 types of assessment for amnionic fluid
- Subjective - Four quadrant - Single pocket - Two-diameter pocket
amniotic fluid is produced by (5)
- Umbilical cord - Membranes - Lungs - Skin - Kidneys
After birth, ductus venosus closes and becomes _____ After birth, umbilical vein closes and becomes ___
- ligamentum venosum -ligamentum teres
-the ___ of the heart is directed toward the left anterior chest -___ is the closest to the chest wall -___ is the closest to the spine
-apex -right ventricle -left atrium
brain - 4 segments of the lateral ventricles
-frontal horn -body -occipital -temporal
umbilical vein diameter: -max diameter of ___ by 30 weeks
0.9 cm
placental grades - should not be seen before __ weeks grade 1 grade 2 grade 3
1 should not appear before 34 weeks 2 should not appear before 36 weeks 3 should not appear before 38 weeks
5 lobes of the cerebrum
1. Frontal 2. Parietal 3. Temporal 4. Occipital 5. Insula
o absent nasal bone - present in __ to ____ of down syndrome fetuses - also associated with trisomy 18, 13 and monosomy x
1/4 to 1/3
placenta may be visible at __ weeks
10
stomach: -becomes apparent as early as __ week because of swallowed AF -full stomach should be seen in ALL fetuses beyond ___ week of gestation
11 16
the gender of a fetus may be appreciated as early as ____ weeks gestation
12
cranial bones ossify by the __ week
12th
The kidneys are apparent as early as the ____ week of pregnancy.
13
normal fetal urinary bladder visualized by ___ week
15
kidneys can be seen sonographically by the __-__ weeks, and consistently seen by 20th week
15-16
following the __ week, the majority of amniotic fluid is from fetal urination
16
brain - CSP, the space between leaves of the septum pelludicum. Failure to detect prior to __ weeks or after ___ weeks = normal
18 37
adrenal glands: -seen as early as __ weeks -by 23 weeks assume rice grain appearance
20
choroid plexus cysts - in absence of other malformations, this may be a normal finding, resolves by __-__ weeks
24-26
primitive lungs mature and become capable of functioning some time after the ____ week
25
normal cervix in pregnancy is ___ cm or longer
3
in the transverse view of the spine, how many ossification points are visible
3, and they are spaced equidistant
brain - cisterna magna, normal size (what is upper cut off)
3-11 mm with avg size of 5-6 mm ** over 10 mm is abnormal
AFI volume increases up to the __ week then slowly diminishes
34
placental thickness should not exceed
4cm (40 mm)
axial and appendicular skeleton begins to form __ - __ week
6-8
renal pelvis measurement is considered abnormal if: >5 mm before __ weeks >8 mm between ____-___ weeks >10mm beyond __ weeks
>5 mm before 20 weeks >8 mm between 20-30 weeks >10mm beyond 30 weeks
anophthalmia
Absence of eyes
brain - connects the third and fourth ventricles
Aqueduct of Sylvius
chorionic villus sampling detects what
Determines if fetus is at risk for congenital defects
brain - 3 layers of the meninges
Dura mater · outer most layer, protective Arachnoid layer · fibrous, thin middle layer Pia mater · highly vascular inner layer
formula for placental thickness =
GA (weeks) + 10 mm
- located between medulla and cerebrum, -helps regulate respiration, sends signals from spinal cord to cerebrum and cerebellum
Pons
what is the cephalic index
Used to determine the normality of the fetal head shape. CI= BPD/OFDx 100
vermis (of cerebellum)
a small control relay info between the two lateral hemispheres
which of the 4 parameters is the least accurate for fetal age
abd circumference (more for growth)
what test is the most accurate way to determine gender before birth
amniocentesis
(EIF) echogenic intracardiac focus: -appears in many normal pregnancies but is also associated with increased risk of ___ and ___
aneuploidy and cardiac defects
measurement that includes both fetal orbits at the same time to predict gestational age
binocular distance (BD)
frontal bossing vs frontal slanting -each is seen in what pathology
bossing = forehead is more prominent than usual; seen in dysplasias slanting = forehead slopes backward; seen in microcephaly
complete breech
both hips and lower extremities found in lower pelvis - requires c section
head is elongated in the transverse (BPD) and shortened in the anterior posterior plane
brachycephaly
fetal position - head up
breech
brain - the cerebellar hemispheres are joined together by _____
cerebellar vermis
part of brain that helps coordinate movements, balance, posture
cerebellum
part of the brain that is concerned with interpretation of impulses and voluntary muscle activities
cerebrum
____ plane of view is helpful in diagnosis of craniofacial anomalies, like cleft lip
coronal
head is shortened in the transverse (BPD) and elongated in the anterior posterior plane
dolichocephaly
small nose and mid-face hypoplasia recognized components of __
down syndrome
duct between pulmonary artery and aorta; most blood bypasses lungs (which do nor require large amounts)
ductus arteriosus
hypotelorism
eyes fused or closely spaced
Hypertelorism
eyes spaced widely apart
· A fold of dura mater in the cerebral fissure
falx cerbri
what other parameter can be used with the same accuracy as BPD for GA
femur
age range analysis (ARA)
fetal parameters of size and proportionality expressed as age
vernix
flakes of skin and hair
brain - connects the lateral ventricles to the third ventricle
foramen of monro
blood flows from the right atrium directly to the left atrium by way of the
foramen ovale
brain - the ___, or body of the choroid plexus, will fill the lateral ventricle in normal pregnancy. if it appears to float or dangle it can be a sign of abnormally enlarged or dilated ventricles (ventriculomegaly)
glomus
the method whereby the fetus is categorized into small, avg, or large growth percentile
growth-adjusted sonar age (GASA)
what is the importance of visualizing the stomach inferior to the diaphragm
helps to exclude left-sided diaphragmatic hernia
the echogenicity of bowel should be greater than that of liver, however, if it is as echogenic as bone it is considered_______. and is associated with increased risk of aneuploidy and neonatal pathology
hyperechoic bowel
superior to midbrain, the communication relay between the nervous system and endocrine system
hypothalamus
If heart is displaced to the right, could be sign of _____
left-sided diaphragmatic hernia
frontal bones of the skull collapse inward
lemon sign - occurs with spina bifida
when placenta lower edge is 0.5-5 cm from internal cervical os
low-lying placenta
the ___ serve as lateral borders for the heart and are useful in assessing the relationship and position of the heart in the chest
lungs
when placenta is up to but not above the cervical os
marginal placenta previa
-closest part of the brainstem to the spinal cord, -responsible for controlling respiration, heart rate, blood pressure and involuntary reflexes
medulla oblongata
components of the brainstem
medulla oblongata, pons, midbrain (thalamus & hypothalamus)
-between pons and thalamus, -relays brain signals, controls head and eye movements
midbrain
HEAD/BRAIN: by 4.5 weeks, the ____ is formed, it is divided into three primary vessels - prosencephalon, mesencephalon, rhombencephalon
neural plate
cavum vergae
normal prominent posterior continuation of the cavum septum pellucidum
at what weeks are CVS and amniocentesis done (which is done earlier)
o CVS - at 10-12 (14?) weeks o Amniocentesis - at 15-20 weeks
the condition of having a relatively high cranial vault with a high or peaked appearance; it is caused by molding of the cranium, exaggerating the vertical axis or in more severe cases by premature closure of the coronal, sagittal and lambdoidal sutures and with vertical index above 77
oxycephaly
ductus venosus shunts (oxygenated or deoxygenated) blood into the IVC
oxygenated
flattening of the vertex of the skull, often associated with cranial molding
platycephaly
if you cannot identify the urinary bladder with oligo, suspect ___ or __
renal abnormality or premature rupture of membranes
which quadrant of the heart has the moderator band
right ventricle
superior to midbrain, relay system for cerebral impulses
thalamus
the heart lies more transversely in the fetus than in the adult because ___
the lungs are not inflated
fibula or tibia: which is longer which is lateral
tibia is longer fibula is lateral and thinner
fetal urination into sac accounts for nearly _____ volume of AF by the second half of preg
total
-second most common chromosomal trisomy -associated with abnormal quad screen -karyotype demonstrates extra chromosome 18
trisomy 18 / edwards syndrome
T/F BPD should not be used to date a pregnancy in cases of severe ventriculomegaly
true
T/F SAX- centrum (anterior ossification center) is equidistant from the two lamina. normal vertebral laminae angle inward, spina bifida is outward splaying of the laminae
true
T/F absent cord twists in the umbilical cord may be associated with poor pregnancy outcome
true
T/F hand movement counts as a positive demonstration of fetal tone
true
T/F head circumference is less affected by compression (breech, multiple preg, leiomyomas etc) than BPD - more accurate
true
fetal position - head down
vertex
what is one advantage CVS has over amniocentesis
· Can be done earlier in preg than amniocentesis o CVS - at 10-12 (14?) weeks o Amniocentesis - at 15-20 weeks
list the 4 types of placental previa
· Complete · Partial · Marginal · Low-lying
Trisomy 13 / Patau Syndrome - associated with
· Holoprosencephaly · Meningomyelocele · Micrognathia · Cleft lip and palate · Heart defects · Echogenic chordae tendineae · Omphalocele · Renal anomalies · Polydactyly · Talipes
list 5 risk factors for placental previa
· Hx of previa · Hx of C-section · Increased age · Increased parity · Hx smoking
Four quadrant AFI · Normal = · Low = · Oligo = · Poly =
· Normal = 8- 20 · Low = 5-10 cm · Oligo = >5cm with largest vertical pocket measuring 2 cm of less · Poly = >24, largest vertical pocket 8cm or more
trisomy 18/edwards - associated with
· choroid plexus cysts · Cerebellar hypoplasia · micrognathia · cleft lip and palate · heart defects · CDH congenital diaphragmatic hernia · omphalocele · renal anomalies · clenched hands · talipes