Page 20 Flashcards
Fetal position where the thighs are flexed at the hips with the legs and knees extended
frank Breech
Thighs are flexed at the hips and there is flexion of the knees as well
complete breech (least common)
With what type of breech is the risk of cord prolapse greatest?
footling
-One or both hips and knees are extended
footling
With what type of breech is the risk of cord prolapse least?
frank
What variation of umbilical cord anatomy occurs when fetal vessels cross the internal cervical os in an attempt to reach the main substance of the placenta?
vasa previa
Name the aneuploidy: growth restriction, prominent occiput, small mandible, short sternum, clenched hands, rocker-bottom feet, choroid plexus cysts (25%)
trisomy 18
Name the aneuploidy: short stature, brachycephaly, flat occiput, short neck with redundant skin on the nape, short broad hands, and hypotonia
trisomy 21
Most efficient multiple-marker screening test in the 2nd tri
quad screen
Name the aneuploidy: severe CNS malformations such as holoprosencephaly, growth restriction, cleft lip and palate, microphthalmia, polydactly, clenched hands with overlapping digits, and renal abnormalities as polycystic kidneys
trisomy 13
Name the aneuploidy: short stature, ovarian dysgenesis, infertility, webbed neck, peripheral
lymphedema at birth, renal abnormalities. Prenatally, increased nuchal translucency or cystic hygroma, lymphangiectasia, CHDs particularly left-sided obstructive lesions such as COA
Turner (45, X)
Low levels of AFP and uE3 and elevated levels of hCG and inhibin A
Down
Embryonic development
- pre-organogenetic phase - conception untile somite formation - all or none period
- embryonic period - weeks 3 to 8 - organogenesis period, max sensitivity to teratogenicity 3. fetal phase
AFP, uE3, and hCG are all low
trisomy 18
Single most powerful marker for differentiating Down syndrome from euploid pregnancies
(1st tri sonographic measurement of the) fetal nuchal translucency space
Most powerful marker for general population screening for Down syndrome
nuchal translucency sonography
Ideal time to screen for fetal aneuploidy
1st tri
Aneuploidies associated with septated cystic hygroma
Down (mc), Turner, and trisomy 18
Most sensitive and specific single marker for the midtrimester detection of Down syndrome
thickened nuchal fold
Some of the MC sonographic markers seen in the 2nd tri
nuchal fold thickening, echogenic intracardiac focus, shortened long bones, hyperechoic bowel, renal pyelectasis, choroid plexus cysts, clinodactyly, hypoplastic or absent nasal bone
What term refers to the combination of generalized hydrops and cystic hygroma?
ymphangiectasia
What is associated with absence of the fetal nasal bones on 1st tri US?
Down
Most helpful in detecting trisomy 21 between 17 and 19 wks AOG
short femur
After gestational sac, what is the next visible landmark that can be used for pregnancy dating?
yolk sac
Position of cursors in measuring BPD
outer to inner, inner to outer, middle of wall to middle of wall
What is often the 1st feature of fetal hydrops revealed by US in early pregnancy?
generalized skin edema
Skin edema is best and most clearly observed where?
fetal head, more specifically, at the back of the neck
Classic triad of signs suggestive of congenital toxoplasmosis?
chorioretinitis, intracranial calcifications, hydrocephalus
Overall the most sensitive marker for trisomy 18
short ear length
Chorionicity and amnionicity of pregnancy in twin-to-twin transfusion syndrome
monochorionic diamniotic
Level of cervical fusion in Apert syndrome?
C5-C6
Often the first manifestation of hydrops?
ascites
(Which side of the body is more often affected in Poland syndrome?)
right
(1st sonographic finding in Meckel syndrome)
oligohydramnios
Most characteristic prenatal feature of monosomy X (Turner) syndrome?
cystic hygroma
What is the first definitive sonographic finding to suggest early pregnancy? / What is the earliest unequivocal sign of pregnancy using sonographic evaluation? / What is the first structure that can be measured for the purpose of calculating GA?
gestational sac / chorionic sac
Position of cursors in measuring HC
outer to outer
Describe the “arrow” that must be seen in measuring the HC
cavum septi pellucidi and frontal horns are the feathers 3rd ventricle and sylvian aqueduct are the shaft ambient and quadrigeminal cisterns and tentorial hiatus are the arrowhead
(Note: cavum septi pellucidi must be visible in the anterior portion of the brain and the tentorial
What is technically the easiest to measure among the common biometric measurements?
femur length
What is the most difficult of the four measurements that are ordinarily obtained?
abdominal circumference
In what plane should you measure the AC?
right and left portal veins are continous with one another
What is the type of placentation of conjoined twins?
monochorionic-monoamniotic
What is the only criteria diagnostic of monochorionic-monoamniotic twins?
single amniotic cavity
dichorionic-diamniotic
With rare exceptions, what is always the type of placentation of dizygotic twins?
dichorionic-diamniotic
What is the most important predictor of the pregnancy-related complications in twin gestations?
type of placentation (chorionicity, not zygosity)
What is the amnionicity if there are 2 yolk sacs?
diamniotic
What is the chorionicity if more than 2 membrane layers are seen?
dichorionic
What is the chorionicity if 2 layers in the dividing membrane / membrane layers are seen?
monochorionic
What type of placentation is more likely if there is a thicker dividing membrane?
dichorionic-diamniotic
What is the chorionicity if there are differing genders?
dichorionic
With what conditions has premature or accelerated placental calcification been associated?
chronic maternal HTN, preeclamppsia, IUGR, smoking
What is the most accurate predictors of dichorionic placentation?
twin-peak sign / separate placentas
What are the common etiologies for hypoechoic placental lesions which are often of no clinical significance?
intervillous thrombus and decidual septal cysts (others: perivillous fibrin deposition/placental surface cysts, placental/venous lakes)
The most informative areas to find the dividing membrane are near what fetal structures?
neck, chin, limbs
What hypoechoic placental lesions are typically located at the periphery of the placenta, resulting in triangular or rectangular areas of fibrin deposited under the fetal surface of the placenta, with the base of the triangle along the chorion?
perivillous fibrin deposition/placental surface cysts
What are sonolucent intraplacental spaces sometimes with swirling internal echoes and shape that may be modified with change in maternal position or uterine contractions?
placental / venous lakes (no clinical significance)
In what conditions have placental lakes been variably reported?
Rh incompatibility, elevated maternal serum AFP, edematous placentas
In what area of the placenta is placental infarction more commonly located
periphery
With what conditons have placental infarctions been associated?
post-term, maternal HTN, anticardiolipin