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36 Cards in this Set

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Intrauterine Growth Restriction (IUGR)
1. def?
2. is this more concerning early or late during preg?
1. FETUS whose weight is less than 10%ile of a specific population at a given gestational age
2. early
Small for Gestational Age (SGA)
1. def?
INFANT whose birth weight is less than 10%ile for gestational age
What are IUGR fetuses at risk for?
intrauterine death, acidemia, asphyxia, intolerance to labor, low APGAR scores, polycythemia, hyperbilirubinemia, hypoglycemia, hypothermia, apnea, respiratory distress, seizures, sepsis, meconium aspiration, and neonatal death
-- the smaller the baby with IUGR- the greater the risk for M&M
1. Early in fetal life how does fetal growth occur?
2. what are the effects of early IUGR?
1. cellular hyperplasia/cell division
2. decreased organ size and maybe function, heritable factors, immune abn, chronic maternal disease, fetal infection, and multiple pregnancies
1. Late is fetal life how does fetal growth occur?
2. how does early vs late IUGR differ
1. cellular hypertrophy (increase in cell size)
2. decreases in cell size/ organ size as with late IUGR may be replenishable by adequate nutrition. May be due to ureteroplacental insufficiency as after 37 weeks there is a steady decline in placental surface area and function due to microinfarctions
What happens to fetal size/growth after 37 weeks gestation?
rate of growth decreases and fetus replaces fat for cellular growth
when does the placenta reach max size? how big is it then?
at 37 weeks it reaches max surface area of 11 m2 and weight of 500 g-- thereafter slow and steady decline due to microinfarctions
low birth weight def?
< 2500 g
Macrosomia
estimated fetal weight > 4000-4500 g
Large for gestational age (LGA)
birth weight >90%ile for gestational age according to population-based norms
what fraction of fetuses categorized as IUGR will actually just be constitutionally small?
2/3
Risk Factors associated with IUGR
1. Maternal factors (HTN, viral infections (rubella, varicella, CMV) early in pregnancy, renal disease, restrictive lung disease, DM, cyanotic heart disease, antiphospholipid syndrome, collagen-vascular disease, hemoglobinopathies
2. smoking and substance abuse
3. severe malnutrition
4. primary placental disease
5. multiple gestation
6. genetic disorders
7. exposure to teratogens (anticonvulsants, warfarin, folic acid antagonists
8. extremes of maternal age <16 or >35
women who smoke are __ to __ X more likely to have fetal IUGR. Their babies usually weigh ___ g less than babies of non-smokers.
3-4; 200
fetal risk factors for IUGR
1. female gender
2. chromosomal abn
3. genetic syndromes (Beckwith Weideman)
4. single gene mutations (glucokinase)
5. mulitples
placental risk factors for IUGR
1. defective trophoblast invasion
2. uterine abn (septum or fibroids)-- limit implantation
3. confined placental mosaicism
How much does fundal height increase every week between 20-36 weeks gestation?
1 cm
If IUGR is suspected what test should be performed?
Fetal US with fetal biometry measures-- apply this to standardized table
What are the four standard fetal measurements of fetal biometry?
1. biparietal diameter
2. head circumference (HC)
3. abdominal circumference (AC)
4. femur length
** serial biometrical measurements allow for assessment of fetal growth rate
1. What does the combination of IUGR and oligohydramnios indicate?
2. what is the mechanism of oligo in IUGR?
1. severe disease and increased morbidity
2. decreased perfusion via placenta creates compensatory redistribution of fetal blood to brain, heart and adrenal glands, resulting in less blood flow to kidneys and less UOP which is the main determinant of amt of amniotic fluid in 2nd half of preg
What are some types of direct invasive studies of the fetus?
1. amniocentesis- test amniotic fluid for fetal lung maturity, fetal karyotyping, viral cultures, PCRs
2. chorionic villus sampling (rarely done)
3. direct blood sampling (percutaneous umbilical blood sampling)
doppler velocimetry
1. what is it?
2. what does it measure?
1. US doppler of fetal vessels-- perform once IUGR diagnosed
2. measures fetal-placental circulation in the umbilical artery via systolic/diastolic ratio (S/D ratio)-- indirectly measures impedance/resistance to flow in the within the placenta
1. What is a normal S/D ratio?
2. What happens to the S/D ratio when there is increased placental resistance?
3. what S/D signifies poor fetal outcome
1) 1.8-2.0
2) S/D ratio increases because diastolic flow decreases
3) if there is absent or reversed diastolic flow
What should happen to flow in the middle cerebral artery (MCA) of fetuses when there is reduced placental perfusion?
There should be compensation to maintain brain perfusion so there should be increased diastolic and mean blood flow velocity in the MCAs-- if not-- poor px
what does abnormal blood flow in the ductus venosus indicate?
very high risk of adverse outcome in setting of IUGR
Management of IUGR
1. serial fetal biometry to assess growth rate and size every 3-4 weeks
2. fetal monitoring such as fetal mov't counts, NST, BPPs and doppler studies
3. optimize time of delivery-- deliver when risk of intrauterine death exceeds neonatal death risk
* There are no specific txs
What conditions do you need to monitor for in neonates with IUGR?
1. respiratory distress
2. hypoglycemia (not enough fat to metabolize for glucose prod)
3. hypothermia
4. hyperviscosity syndrome
* if survive neonatal period, then good px
what is hyperviscosity syndrome? what does it result from? What does it lead to?
marked polycythemia in IUGR neonates due HCT > 65% in order to compensate for poor placental oxygen transfer.
This leads to multiorgan thrombosis, heart failure and hyperbilirubinemia
Maternal risk factors for macrosomia
1. inc maternal pre-preg weight
2. weight gain during preg
3. multiparity
4. male fetus
5. gestational age > 40 weeks
6. maternal birth weight
7. maternal height
8. h/o macrosomia in prev preg
9. maternal age < 17 yo
10. positive 50 g glucose screen with negative 3 hour
11. high triglycerides
Fetal risk factors for macrosomia
1. genetic potential
2. genetic disorders (beckwidth weideman)
3. male sex
risks to mother with in fetal macrosomia
1. inc risk of C/S
2. inc risk of post partum hemorrhage due to inc risk of vaginal lacs
3. UTIs in elective C/S
4. puerperal fever after TOL
risk to fetus with macrosomia
1. shoulder dystocia
2. clavicle fx
3. low APGAR scores
If obesity or GDM = etiology then inc risk of: hypoglycemia, hypothermia, hyperbili, prematurity, and stillbirth
long-term: inc risk of obesity
*brachial plexus injury is rare*
two primary methods of fetal weight estimation
1. leopald maneuvers-- abdominal palpation
2. fundal height (measurement of height of uterine fundus above pubic symphysis)
* US can also be used with some regression formulas-- but has not proven better than clinical estimates
DDX of enlarged uterus
1. large fetus
2. multiple gestation
3. polyhydramnios
4. large placenta (molar pregnancy)
5. large uterus (uterine leiomyomata, gyn tumor, abn)
Management of macrosomia
1. induction of labor?
2. elective C/S?
1. do NOT induce labor early-- no evidence to support dec morbidity, but does increase risk of C/S
2. There is no specific weight above which women should undergo elective C/S however it should be offered to non diabetic -women with estimated fetal weight > 5000 g and diabetic women with > 4500 g weight
ways to facilitate delivery in the case of shoulder dystocia
1. exaggerated flexion of the thighs (mcRobert's maneuver)
2. suprapubic pressure
3. episiotomy
4. delivery of the posterior arm
5. intentional clavicle fx
indications for C/S with macrosomic fetuses
prolonged 2nd stage or arrest of descent in 2nd stage