assessment of abnormal fetal growth (week 3)

growth problems caused by placental insufficiency may benefit from

early delivery

IUGR may be due to

fetal causes, placental insufficiency

you can have symmetric or asymmetric

fetal causes of IUGR

chromosomal abnormalities

congenital malformations and syndromes

fetal infections

multiple GA

placental insufficiency is a term used to describe

inadequate nutrient and oxygen delivery to the fetus from the placenta

70-75% IUGR is caused by

placental insufficiency (fetus may benefit from increased monitoring and surveillance

IUGR is most commonly caused by

maternal or placental disorders

IUGR- caused by maternal disorders (behavior related):

smoking

alcoholism

poor nutrition

drug use

Chronic maternal medical conditions that effects systemic oxygenation or uteroplacental circulation

-chronic hypertension

diabetes type one

anemia

heart conditions

chronic lung disease

thrombophilia

IUGR is the result of

disturbances in placental vascular disruption

placental abnormalities associated with IUGR

placental abruption

placental infarcts

placental previa

placental neoplasms

placental vascular anastomes in monochorionic multiple GAs

post mature pregnancy

IUGR- other causes

high altitude (low oxygen levels)

irradiation

maternal age under 17 or over 35 years of age

IGUR symmetric;

proportionally small fetus (head, body, extremities)

associated with first trimester insults such as

fetal infection

congenital malformations

high altitude

irradiation

IUGR asymmetric:

abdomen is proportionally smaller for GA than head and extremities

associated with IUGR caused by placental insufficiency

what’s brain sparing phenomenon

preferential circulation to the brain at the expense of other fetal organs

in response to low oxygen and poor nutrition, the arterial resistance to blood flow in the brain….

decreases in order to allow more blood flow

decreased arterial flow to the kidneys and liver results in…

kidneys- decreased urine output

liver- smaller abdominal size

IUGR- post partum risks and complications for the neonate

asphyxia

respiratory distress syndrome

meconium aspiration

stillbirth

low birth weight

decreased Apgar score

learning disabilities in later years

IUGR sonographic findings maybe

-abdominal circumference maybe small for GA

-head/abd circumference ratio may be increased

-fetal weight will be at or below the 10th%

AFV may be decreased

placenta may be thin

grade 3 placental seen before 34 wks

large for GA is defined as

a fetus greater than the 90% for GA

fetal macrosomia:

fetal weight of 4000 grams or greater

higher risk for maternal and fetal injury such as shoulder dystocia, fractures, facial and brachial plexus paises

LGA risk factors

gestational diabetes

type ½ diabetes

multiparity

mom age

mom weight and obesity

post term delivery

hx of LGA fetus

LGA sonographic findings (abdominal circumference);

diabetic pregnancies exposed to high levels of glucose demonstrate accelerated thoracic and abdominal growth

-polyhydraminos

most common approach to diagnosing LGA and macrosomia

EFW

high risk factors for fetal well being that require increased surveillance

fetal macrosomia due to poorly controlled diabetes

women with combinations of renal disease, hypertension and IUGR

assessing fetal well being would include evaluating

for fetal distress due to asphyxia

BPP (biophysical profile)

what’s BPP

assessment of fetal well-being or fetal distress

sonographic criteria for BPP would be that the fetus has 30 minutes to demonstrate:

fetal movement; 3 or more gross body movements

fetal breathing; at least 30 seconds of fetal breathing or hiccups

fetal tone; at least one episode of extension with return to flexion

AFV; at least one pocket that measures 2cm or more in vertical diameter

non stress test for a baby means

non imaging test using stimuli to test fetal heart reactivity, fetus should demonstrate at least two to five fetal heart accelerations

MCA (middle cerebral artery)- indications

fetal anemia

IUGR

hydrops

isoimmunization

sonographic technique for MCA

axial scan plane

locate circle of willis

use color doppler

what kind of spectral doppler would you see for the MCA

high impedance circulation with forward flow during diastole

in the normal situation the fetal MCA has a high resistance flow which means there is

minimal antegrade flow in fetal diastole

cerebroplacental ratio;

>1:1 is normal and <1:1 is abnormal

slide 20

fetal MCA systolic/diastolic (S/D) ratio:

a normal fetal MCA S/D ratio should

always be higher than the umbilical arterial S/D ratio

The fetal middle cerebral artery (MCA) pulsatility index (PI) is a key fetal parameter used in

fetal middle cerebral arterial Doppler assessment.

fetal middle cerebral artery (MCA) pulsatility index (PI) is calculated by

subtracting the EDV from the PSV and then dividing by the time- average velocity

The fetal MCA PI normally has a ____ ____. The mean value (normal reference range) slowly ___ through gestation from around 28 weeks onwards. A low PI reflects the redistribution of cardiac output to the brain due to….

high value

decreases

the fetal head sparing theory

The fetal middle cerebral arterial (MCA) peak systolic velocity (PSV) is an important parameter in

fetal MCA doppler assessment

how should the fetal MCA be measured

2mm from origin of the fetal internal carotid artery and the angle of the US beam and the direction of blood flow should be 0

MCA PSV is reliable during that wks

18-35 wks

increased PSV can indicate moderate-to- severe anemia in non-hydrops fetuses

fetal MCA systolic/diastolic (S/D) ratio is an important parameter in

fetal middle cerebral arterial doppler assessment

fetal MCA systolic/diastolic (S/D) ratio is a useful predictor of

fetal distress and IUGR

During pregnancy the middle cerebral (and other intracranial) arteries demonstrate

high resistance waveforms, high systolic velocity and low/ absent diastolic velocity

A normal fetal MCA S/D ratio should always be higher than the ….

umbilical arterial S/D ratio.

reduced MCA s/d ratio is

abnormal and implies an increased diastolic flow in MCA, loss of high resistive waveform is also an indicator of fetal distress or IUGR

what’s cerebroplacental ratio?

obstetric US tool used as a predictor of adverse pregnancy outcome in both small for GA and appropriate GA fetuses

an abnormal CPR ratio reflects

redistribution of cardiac output to the cerebral circulation and has been associated with intrapartum fetal distress, increased rates of emergency cesarean and NICU admissions and poorer neurological outcomes

. An abnormal cerebroplacental ratio may result in the following condition

-low normal range MCA and upper normal range UA PI

- abnormal low MCA and normal UA PI

-abnormal low MCA and high UA P

decreased resistance in the MCA would show

brain sparing

the fetal head sparing theory is one that underpins;

asymmetrical intra-uterine growth restriction, where the difference between normal head circumference and decreased abdominal circumference is attributed to the fetus’s ability to preferentially supply the cerebral, coronary, adrenal and splenic circulations

In a situation of chronic fetal hypoxemia, the fetus redistributes its cardiac output to maximize…

the oxygen supply to brain by vasodilation of the cerebral arteries thereby causing a decrease in the left ventricular afterload

when is fetal ductus venous flow assessment be useful for a fetal ultrasound

-first tri screening for aneuploidy/ anomalies

second and third trimester scanning when there are concerns

IUGR

fetal cardiac compromise

advanced placental insufficiency will result in diminished

cardiac function

ductus venous sonographically

waveform reflects status of the rt ventricle

transaxial view through the fetal abdominal at AC PLANE

COLOR DOPPLER DV AS IT BRANCHES FROM THE PORTAL VEIN

the triphasic wave form of the ductus venous compromises of;

S wave- corresponds to fetal ventricular systolic contraction and is the highest peak

D wave- corresponds to fetal early ventricular diastole and is the second highest peak

A wave- corresponds to fetal atrial contraction and is the lowest point in the wave from albeit still being in the forward direction

reversal of what waveform is always abnormal when regarding ductus venosus

A wave

zygosity and the different types;

number of ovum fertilized

monozygotic- one ovum was fertilized and single zygote has divided into two

dizygotic- two ovum are fertilized the two zygotes develop into twins

chorionicity (AKA placentation)/ amniocity;

number of chorions that develop

number of amniotic sacs

monozygotic twins vs dizygotic twins

mon; identical twins, one sperm and one egg

di; fraternel, two eggs, two sperms

n 14% of MZ twins, the two placentas ___

fuse

in about 2/3 of MZ twins, the split takes place after…

the placenta has formed

how to labels twins when doing an exam

twin A is the twin closer to the internal OS

most common complication of twins is

prematury

twins are 8 times more likely than singletons to have a birth weight

less than 1500 grams, triplets are 33 times more likely

monozygotic twins are two times more likely to have a congenital anomaly than a singleton, however…

dizygotic twins are not an increased risk

twin gestations have an increased risk for

-cerebral palsy

-(monochorionic twins have a mortality rate of two to three times that of dichorionic twins)

maternal complications with twins

pregnancy induced hypertension

preeclampsia

gestational diabetes

premature rupture of membranes

central vascular anastomoses will develop in

virtually all monochorionic gestations

in some instances, central vascular anastomoses will create a shared and unbalanced circulation pattern that may result in…

syndromes unique to monochorionic multiple gestations

unidirectional shunting occurs deep in the placenta, but is balanced by

superficial shunts that are bidirectional

unbalanced fetal circulation will occur if there is not enough

superficial anastomoses

twin to twin transfusion syndrome is usually caused by

arteriovenous anastomosis (artery and vein approach each other on the chorionic plate and enter into a single cotyledon)

occurs in 5-30% of monochorionic twins

what happens to the donor twin with twin to twin transfusion

donor twin becomes anemic, growth restriced, develops oligohydraminos

what happens to the recipient twin with twin to twin transfusion

normal in size or edematous and develop polyhydraminos

treatment options regarding oligohydarminos and polyhydraminos with twin to twin transfusion

serial amniocentesis to reduce fluid size or laser occlusion of the communicating vessel

stuck twin syndrome (aka poly-ole sequence) occurs when

there is polyhydraminos in one amniotic sack and oligohydraminos in the other

poly(may be due to fetal anomaly)

TRAP sequence is

a rare condition of monchorionic twin pregnancies

acardiac anomaly or parabiotic twin

1 in every 35,000 pregnancies (occurs randomly)

when the pump twins heart does the work for supplying both twins with blood, one doesn’t have a heart

what causes TRAP

artery to artery or vein to vein anastomoses

very early in pregnancy, a dramatic ongoing fluctuation of blood pressure and blood flow may interfere with the development of the heart in the acardiac twin

does the pump twin in trap have a good survival rate

50-55% due to polyhydraminos due to increased blood flow to the kidneys results in overproduction of urine, may result in premature delivery

TES (twin embolization syndrome);

results from second trimester demise of a eco- twin in a monochorionic pregnancy

what would cause an acute hypotensive event in TES

vascular connections may allow exsanguination of the surviving twin into the demise twin

two mono amniotic complications would be

conjoined twins or cord entanglement

how does conjoined twins occur

rare, incomplete division of the embryonic disc results in shared organs and body parts

most common type of conjoined twins

thoracopagus- when anterior thorax of each twin is conjoined

less common; omphalopagus- when the ant abdomens are conjoined

most common effect of excess maternal glucose levels (diabetes mellitus) would be

fetal overgrowth (macrosomia)

birth trauma (shoulder dystocia)

high glucose levels are present during organogenesis

type one diabetes is also known as

insulin dependent diabetes

inability of the panc to produce insulin resulting in excessive glucose levels

what neural defects are associated with diabetes type one

spina bifida

anencephaly

caudal regression syndrome

what cardiac anomalies are associated with type 1 diabetes

transposition of the great vessels

tetralogy of fallot

renal abnormalities associated with type one diabetes

hydrogenesis and renal agenisis

gastrointestinal abnormalities associated with type 1 diabetes

duodenal atresia and anorectal atresia

Maternal vascular damage can affect uteroplacental circulation leading to

IUGR or oligohydraminos

Exposure to excess glucose can cause overgrowth of the fetus such as

• Macrosomia

• Placentomegaly (thick placenta)

• Polyhydramnios

• Other side effects that may affect the fetus

• stillbirth

• neonatal hypoglycemia

• erythroblastosis

gestational diabetes usually occurs during what trimester plus effects on the fetus

second, not associated with fetal anomalies but associated fetal effects would be mascrosomia, polyhydraminos and placentomegaly

maternal hypertension:

140/90 mmHg

chronic- present before 20 wks GA

pregnancy induced- caused by prostaglandin abnormalities

types; preeclampsia and eclampsia

what would you get with preeclampsia if there’s also maternal hypertension

high blood pressure

proteinuria

edema

rapid weight gain

what would you get with eclampsia if there’s also maternal hypertension

presence of seizures or coma in the preeclamptic pt

headaches

blurred vision

maternal death

fetal death

maternal hypertension- associated with impaired circulation to the placenta and utero placental insufficiency

• Oligohydramnios

• IUGR

• premature labor

• increased incidence of placental abruption

• placental infarcts

• small or thin placenta

• grade 3 placenta before 34 weeks gestation

• abnormal fetal Doppler

what change in fetal doppler will you see when the mom has hypertension

high resistance umb chord (absence or reversed diastolic flow)

low resistance waveform in the middle cerebral artery (increased diastolic flow)

ductus venous waveform demonstrated flow reversal during atrial contraction

treatment for maternal hypertension

bed rest

medication

increased monitoring or both mom and baby