Week 9- DMS 212 Fetal Age and Size 2nd/3rd Trimester and Placenta

biparietal diameter (BPD)

diameter measurement of skull

how is BPD measured

from leading to inner edge of parietal bone

outer calavarian margin to inner calvarium margin

what brain structures should you see when measuring BPD, HC, and OFD

thalamus!!!, cavum septum pellucidum, falx

binocular distance (BOD)

measurement from outer orbit to outer orbit of the lenses

interocular distance (IOD)

measurement from inner orbit to inner orbit

cephalic index (CI)

ratio of BPD to OFD

occipito-frontal diameter (OFD)

outer to outer measurement from the frontal bone to the occipital bone

head circumference

circumference of the transverse skull

how is head circumference measured

outermost perimeter not including the scalp

macrosomia

fetus weight over 4000g or 8lb 13oz

how is OFD measured

outer to outer

at same level as BPD

the ___________________, _____________________, and __________________ can all be measured in the same image

cerebellum

cisterna magna

nuchal fold

other fetal brain structure measurements

lateral ventricles: no more than 10 cm

cerebellum: 1 mm

cisterna magna: 3-10 mm

nuchal fold: 6 mm

list the standard routine measurements

BPD, HC, CI, cerebellum, cisterna magna, nuchal fold

binocular/interocular, AC, FL, HL

measurement accuracy can be achieved by

multiple measurement average

the nuchal fold measurement can no longer be taken after _________ weeks

24

what structures you should see when measuring abdominal circumference

portal vein, umbilical vein, stomach

list the anatomic landmarks for abdomen measurements

junction of umbilical vein/portal vein, stomach, AO, spine, circular shaped abdomen

list the long bones

femur, humerus, tib/fib, radius/ulna

when measuring long bones only include the

echogenic part

succenturiate lobe

extraplacental lobe smaller than the placenta

braxton-hicks

uterine contractions that do not lead to labor

cotyledons

subdivisions of the maternal placenta containing fetal vessels, chorionic villi, and intervillous spaces

decidua

functional layer of the endo post-ovulation/during pregnancy

retroplacental

vascular area between the myometrium and placenta

wharton jelly

Mucous tissue surrounding the umbilical cord

central insertion

cord inserts into middle of placenta

marginal insertion

cord inserts near the edge of the placenta

velamentous insertion

cord inserts into chorioamniotic membranes

marginal insertion is also called

battledore

velamentous insertion increases the likelihood of _______________________

vasa previa

vasa previa

umbilical cord crosses over the internal os

Grade 0 placenta

no calcs

Grade 1 placenta (31-36wks)

scattered calcs

Grade 3 placenta (36-38wks)

basal calcs with increased lobulations

Grade 4 placenta (38wks-term)

basal and interlobar septal calcs

the placenta matures considerably after the ___________ week

40th

Most term pregnancies have grade ___ or ___ placentas

1 or 2

only about 10-15% of term pregnancies are grade _____

3

what must be evaluated when examining the cervix

cervical length

incompetency

funneling

what is the correct way to measure the cervix

from internal os to external os

normal cervical length

2.5 to 3 cm

what is the gold standard for measuring the cervix

TV

clinical findings of cervical incompetence

painless dilation

premature rupture of mems

vaginal bleeding

cervical length less than 3cm

funneling

funneling of the cervix

list some indication for cervical evaluation

hx of premature labor/birth

multiple gestation

Premature rupture of mems

uterine anomaly

DES exposure

funneling

premature opening of the internal os

PROM

premature rupture of membranes

cerclage

procedure where circumferential suture closes the cervix

what are the two most common cerclage techniques

shirodkar and McDonald

what is placenta

vital support organ for the fetus

normal measurement of placenta

2-3cm should not exceed 4cm

how is placenta formed

from trophoblastic cells that make up chorion

chorionic villi

functional units of placenta

maternal portion of the placenta

decidua basalis/basal plate

fetal portion of the placenta

chorion frondosum

what is a cotyledon?

consists of a chorionic villi from the fetus and a caruncle from the mother

genetic material in the chorionic villi is the same as the __________________

fetal cells

caruncle

maternal tissue that anchors the cotyledon to the uterine wall

list the functions of the placenta

respiration

nutrition

excretion

hormones

storage

protection

how does the placenta facilitate respiration

oxygen from maternal blood passes through placenta into fetal blood and carbon dioxide returns to maternal blood

how does the placenta produce hormones

synctiotrophoblast cells produce estrogen, hCG, and progesterone

sono appearance of placenta

solid

homogenous

medium gray

smooth borders

list the locations of the placenta

fundal anterior

posterior

fundal posterior

right or left lateral

causes of premature maturation of the placenta

maternal HTN

smoking

IUGR

multiple gestation

causes of delayed maturation of the placenta

maternal diabetes

obesity

fetal congenital heart disease

fetal chromosomal abnormality

placentomegaly

enlarged placenta

AP over 4cm

causes of placentomegaly

maternal diabetes

isoimmunization

fetal-maternal hemorrhage

intrauterine infection

non-immune hydrops

chromosomal anomaly

uterine anomaly

twin-twin transfusion

congenital neoplasm

triploidy

placental insufficiency

placenta under 1.5cm

causes of placenta insufficiency

placental infarction

chromosomal anomaly

intrauterine infection

diabetes

IUGR

preeclampsia

polyhydramnios

toxemia

placenta previa

placenta covers the internal os of the cervix

if the placenta is low lying in the second trimester is is often...

self correcting and is pulled up as the uterus grows

complete previa

placenta totally covers internal os

partial previa

partially covering internal os

marginal previa

small edge extends to the margin of internal os

low lying

not considered previa but need monitoring

placental edge is less than 2cm away from internal os

what is the most common cause of painless bleeding in the 2nd and 3rd trimester?

placenta previa

risk factors for placenta previa

multiple gestations

multiparous women

prior C-section

hx of abortion

advanced maternal age

closely spaced preg

abnormal fetal position

hx of fibroids

maternal anemia

hx of uterine infection

an __________________________ can cause the illusion of placenta previa

overdistended bladder

_________________ can mimic low lying placenta

uterine contraction

succenturiate placenta

bilobed placenta/accessory lobe connected to placenta by vessels

succenturiate placenta can increase likelihood of ________________________

vasa previa

placental lakes

enlarged spaces in the placenta filled with maternal blood

Placenta accreta

superficial invasion of the placental villi into decidua

placenta increta

deeper invasion of villi into myometrium

placenta percreta

invasion of villi through myometrium and often into bladder wall

placenta 'cretas can cause __________________ due to _______________

maternal death, exsanguination

sono eval of placenta 'cretas

assess placental/myometrial borders

use high res TDR

ID borders

___________ may be useful in identifying placenta 'cretas

MRI

abruptio placenta

placenta tears away from uterine wall before birth; can be life threatening to fetus and mother

abruptio placenta is known as

placental abruption

retroplacental abruption

Rupture of spiral arteries and high pressure bleed

sono appearance of retroplacental abruption

thick placenta

possible clot in area of abruption

marginal placental abruption

rupture of marginal vein and low pressure bleed

sono appearance of marginal placental abruption

anechoic or hypoechoic bleed in subchorionic area usually at edge of placenta

placental abruptions are an ______________________

OB emergency

placental abruptions may result in...

premature labor or delivery

fetal demise

symptoms of placental abruption

vaginal bleeding

painful contractions

sudden onset of severe abdominal pain

chorioangioma

benign vascular tumor of the placenta

what is the most common placental tumor

chorioangioma