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