Obgyn Fetal Growth Abnormalities

Front 1

Intrauterine Growth Restriction (IUGR)
1. def?
2. is this more concerning early or late during preg?

Back 1

1. FETUS whose weight is less than 10%ile of a specific population at a given gestational age
2. early

Front 2

Small for Gestational Age (SGA)
1. def?

Back 2

INFANT whose birth weight is less than 10%ile for gestational age

Front 3

What are IUGR fetuses at risk for?

Back 3

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

Front 4

1. Early in fetal life how does fetal growth occur?
2. what are the effects of early IUGR?

Back 4

1. cellular hyperplasia/cell division
2. decreased organ size and maybe function, heritable factors, immune abn, chronic maternal disease, fetal infection, and multiple pregnancies

Front 5

1. Late is fetal life how does fetal growth occur?
2. how does early vs late IUGR differ

Back 5

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

Front 6

What happens to fetal size/growth after 37 weeks gestation?

Back 6

rate of growth decreases and fetus replaces fat for cellular growth

Front 7

when does the placenta reach max size? how big is it then?

Back 7

at 37 weeks it reaches max surface area of 11 m2 and weight of 500 g-- thereafter slow and steady decline due to microinfarctions

Front 8

low birth weight def?

Back 8

< 2500 g

Front 9

Macrosomia

Back 9

estimated fetal weight > 4000-4500 g

Front 10

Large for gestational age (LGA)

Back 10

birth weight >90%ile for gestational age according to population-based norms

Front 11

what fraction of fetuses categorized as IUGR will actually just be constitutionally small?

Back 11

2/3

Front 12

Risk Factors associated with IUGR

Back 12

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

Front 13

women who smoke are __ to __ X more likely to have fetal IUGR. Their babies usually weigh ___ g less than babies of non-smokers.

Back 13

3-4; 200

Front 14

fetal risk factors for IUGR

Back 14

1. female gender
2. chromosomal abn
3. genetic syndromes (Beckwith Weideman)
4. single gene mutations (glucokinase)
5. mulitples

Front 15

placental risk factors for IUGR

Back 15

1. defective trophoblast invasion
2. uterine abn (septum or fibroids)-- limit implantation
3. confined placental mosaicism

Front 16

How much does fundal height increase every week between 20-36 weeks gestation?

Back 16

1 cm

Front 17

If IUGR is suspected what test should be performed?

Back 17

Fetal US with fetal biometry measures-- apply this to standardized table

Front 18

What are the four standard fetal measurements of fetal biometry?

Back 18

1. biparietal diameter
2. head circumference (HC)
3. abdominal circumference (AC)
4. femur length
** serial biometrical measurements allow for assessment of fetal growth rate

Front 19

1. What does the combination of IUGR and oligohydramnios indicate?
2. what is the mechanism of oligo in IUGR?

Back 19

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

Front 20

What are some types of direct invasive studies of the fetus?

Back 20

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)

Front 21

doppler velocimetry
1. what is it?
2. what does it measure?

Back 21

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

Front 22

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

Back 22

1) 1.8-2.0
2) S/D ratio increases because diastolic flow decreases
3) if there is absent or reversed diastolic flow

Front 23

What should happen to flow in the middle cerebral artery (MCA) of fetuses when there is reduced placental perfusion?

Back 23

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

Front 24

what does abnormal blood flow in the ductus venosus indicate?

Back 24

very high risk of adverse outcome in setting of IUGR

Front 25

Management of IUGR

Back 25

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

Front 26

What conditions do you need to monitor for in neonates with IUGR?

Back 26

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

Front 27

what is hyperviscosity syndrome? what does it result from? What does it lead to?

Back 27

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

Front 28

Maternal risk factors for macrosomia

Back 28

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

Front 29

Fetal risk factors for macrosomia

Back 29

1. genetic potential
2. genetic disorders (beckwidth weideman)
3. male sex

Front 30

risks to mother with in fetal macrosomia

Back 30

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

Front 31

risk to fetus with macrosomia

Back 31

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*

Front 32

two primary methods of fetal weight estimation

Back 32

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

Front 33

DDX of enlarged uterus

Back 33

1. large fetus
2. multiple gestation
3. polyhydramnios
4. large placenta (molar pregnancy)
5. large uterus (uterine leiomyomata, gyn tumor, abn)

Front 34

Management of macrosomia
1. induction of labor?
2. elective C/S?

Back 34

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

Front 35

ways to facilitate delivery in the case of shoulder dystocia

Back 35

1. exaggerated flexion of the thighs (mcRobert's maneuver)
2. suprapubic pressure
3. episiotomy
4. delivery of the posterior arm
5. intentional clavicle fx

Front 36

indications for C/S with macrosomic fetuses

Back 36

prolonged 2nd stage or arrest of descent in 2nd stage