Ch. 53 Quiz Flashcards
Babies that are smaller than 90% of babies of the same gestational age are called
small for gestational age
Babies that are larger than 90% of babies of the same gestational age are called
large for gestational age
Macrosomia is a term used to describe babies that are
large for gestational age
What percentage of pregnancies are affected by IUGR
3-7%
IUGR is defined as
an EW at or below the growth percentile and an AC that is 2 weeks or more behind the head and femur measurements
Babies that have IUGR are at greater risk for what complications
fetal death, perinatal asphyxia, neonatal morbidity, developmental problems
List the material risk factors for IUGR
maternal hypertension, smoking, uterine anomaly. large retroplacental bleed
Why is it necessary to have an accurate determination of gestational age to diagnose IUGR
in order to diagnose abnormal growth
What causes symmetrical IUGR
small parents, infection, alcohol abuse, first trimester insults
Describe the appearance of symmetrical IUGR
all measurements are small
What causes asymmetrical IUGR
placental insufficiency, maternal diabetes, hypertension, smoking, alcohol, drugs
Describe the appearance of asymmetrical IUGR
small AC by 2 weeks, normal FL & HC
Why is the AC the first measurement affected by asymmetrical IUGR
the liver is the main source for glucose storage
Why is the head the last area affected by asymmetrical IUGR
last organ to be deprived of nutrients, head sparing
What are the clinical signs of IUGR
decreased fundal height and fetal motion
What are the key IUGR sonographic markers
small AC before 36 weeks, grade 3 placenta, decreased placental thickening
The _____ is the most useful measurement for assessing fetal growth/size
AC
The _____ is useful for determining the type of IUGR that is present
HC/AC ratio
Which EFW calculation is more accurate
One which incorporates BPD/HC/AC/FL
Symmetrical IUGR can be diagnosed with a single sonogram
false
How can serial sonograms be used to differentiate between SGA and symmetrical IUGR fetus
plot interval growth and consider maternal/fetal and familial factors
What other factors besides interval growth must be considered when determining SGA vs IUGR
parents, maternal hypertension, paternal size, ethnicity, fetal growth and well being
List 3 causes of oligohydramnios
renal problems, demise, post dates, PROM, preeclampsia
Which measurement is used to determine the normality of the fetal head shape
CI
What is the normal range for AFI
5-22cm
Is the normal range of AFI absolute? Why or why not
no, different values from different sources, normal values change with gest age
Describe placental grade 0
homogenous smooth chorion plate, medium gray
Describe placental grade 1
small hypoechoic/cystic spaces
Describe placental grade 2
small hypoechoic/cystic spaces, calcifications maternal border
Describe placental grade 3
cumulous cloud, heterogenous with calcifications, swirled septations
What percentage of pregnancies will actually have a grade 3 placenta
10-15%
A grade 3 placenta before 34-36 weeks can indicate what
IUGR or placental insufficiency
What is the BPP used for
fetal well being, predict hypoxia
Describe the parameters involved in performing a BPP: fetal breathing motions
one episode that lasts at least 30 sec within 30 min
Describe the parameters involved in performing a BPP: gross body movement
3 large movements within 30 mins
Describe the parameters involved in performing a BPP: fetal tone
one episode flexion/extension of spine or extremity within 30 mins
Describe the parameters involved in performing a BPP: fetal heart rate
increase 15bpm for 15 sec within 30 mins
Describe the parameters involved in performing a BPP: amniotic fluid index
5-22cm
The BPP parameters were designed to correlate with the _____ that is calculated after birth
APGAR
Describe the scoring of the BPP
0 of 2, out of 8 to 10
What is the main goal of the BPP
detect and manage fetal hypoxia
Describe when the centers for each of the BPP parameters develop: fetal tone
7.5-8.5 weeks
Describe when the centers for each of the BPP parameters develop: fetal movement
9 weeks
Describe when the centers for each of the BPP parameters develop: fetal breathing
20-21 weeks
Describe when the centers for each of the BPP parameters develop: reactive heart rate
2nd-3rd trimester
Which centers are the first to be affected by hypoxia
reactive HR, fetal breathing
Is CW doppler used in obstetric imaging
no
With IUGR the umbilical artery will have an ____ S/D ratio
increased
With IUGR the circle of willis will have an _____ S/D ratio
decreased
Why does the circle of willis demonstrate increased diastolic flow in the presence of IUGR
shunting of blood to the brain for protection
What is the upper limit normal for the umbilical artery S/D ratio after 30 weeks
3.0
What fetal complications are associated with elevated umbilical artery S/D ratios
fetal compromise and death, early delivery, NICU
Why does placing the patient on bed rest to the LLD position help improve S/D ratio in the umbilical artery
takes pressure of the uterus off the aorta and IVC, improving maternal flow to uterus
When would S/D ratio not be able to be measured
no diastolic flow
What are the maternal risk factors for macrosomia
multiparous, 35+ year old, post term pregnancy, diabetes, LGA fetus
How does unregulated maternal diabetes contribute to macrosomia
due to decreased maternal blood flow to the placenta, causes hyperinsulinemia, Miracle-Gro
What birth complications are associated with macrosomia
clavicular fractures, facial/brachial palsies, meconium aspiration, perinatal asphyxia, neonatal hypoglycemia, cord compression
List 3 types of mechanical macrosomia and their associated causes
- generally large post term 2. large shoulders diabetic pregnancy 3. large head, hydrocephalus
Why is it important to have very accurate measurements when calculating fetal weight
small errors in measurement can be big errors in weight calculation
Describe the chest circumference measurement and how is it used to detect macrosomia
trans just below heart
How is the macrosomia index calculated
chest diameter - BPD
What is the upper limit of normal for macrosomia index
1.3-1.4
Why would detection of polyhydramnios cause the attending physician to order a glucose tolerance test
polyhydramnios is often seen with diabetic pregnancy
Why is the placenta often thickened in macrosomic babies
because it is stimulated by the increased levels of insulin in the fetal blood
Which fetal measurement is about as accurate as the BPD in determining gestational age
femur length
