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OB > Disorders of Fetal Growth > Flashcards

Disorders of Fetal Growth Flashcards

Sem. 2

1
Q

What is a normal birth weight?

A

normal: 2.5-4kg
low: < 2.5kg
extremely low: < 1kg

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2
Q

What is SGA?

A

small for gestational age
embryos who are smaller in size than normal for the GA, most commonly defined as a weight below the 10th percentile for the GA
WITHOUT referece to cause

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3
Q

What is needed for a fetus to grow?

A

oxygen and nutrients

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4
Q

What is a fetus who is below the 10th percentile for the gestational age called?

A

small for gestational age

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5
Q

What is LGA?

A

large for gestational age

indication of high prenatal growth rate

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6
Q

What is a fetus whose wieght, length, or head circumference that lies above the 90th percentile for that gestational age called?

A

large for gestational age

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7
Q

What is IUGR?

A

intrauterine growth restriction
fetal growth restriction describes subset of SGA fetuses with weight below 10th percentile as result of pathological process from a variety of maternal, fetal, placental disorders

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8
Q

What is the difference between IUGR and SGA?

A

SGA is without reference to cause or pathology

IUGR is a result of pathologic process

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9
Q

What are the two types of IUGR?

A

symmetrical and asymmetrical

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10
Q

What is symmetrical IUGR?

A

when the fetus is proportionally small
result of 1st trimester insult (genetic abnormality, infection)
20-30%

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11
Q

What is asymmetrical IUGR?

A

2/3 of IUGR
not proportional. head is larger than rest of body (head sparing)
result in late 2nd trimester or 3rd (usually from placental insufficiency)

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12
Q

What is head sparing?

A

when the fetal body shunts blood to the brain, leading to a larger head

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13
Q

What is the most common materal cause of IUGR?

A

hypertension

another cause can include diabetes

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14
Q

When IUGR is suspected, what should a sonographer look for?

A

amniotic fluid amount (oligo), biometry (low weight), BPP (low score), umbilical doppler (abnormal umbilical artery flow)

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15
Q

Between 20 to 36 weeks of gestation, what does the fundal height (in cm) equate to?

A

the gestation age in weeks of fetus
should not be more than 2cm difference
3 or more is a lagging of fetal growth

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16
Q

What can you expect from an IUGR baby?

A

increased corticol and adrenaline
can easily become hypothermic
thrombosis (within kidney or mesenteric artery) due to more blood being produced, so it becomes thicker causing the thrombus

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17
Q

What are risk factors for SGA infants and decreased growth potential?

A

genetic and chromosomal abnormalities (Russel-Silver Syndrome, Trisomies),
intrauterine infections-TORCH (toxoplasmosis, others(syphilis, varicella roster), rubella, cytomegalo virus (CMV), herpes),
teratogenic exposure, substance abuse (fetal alcohol syndrome), drugs-beta blockers/ACE inhibitors, nicotine smoking, radiation exposure, pregnancy at high altitudes, small maternal stature, female fetus

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18
Q

What are the signs of Russel-silver syndrome?

A

postnadal growth retardation, small triangular face with distinctive facial features including a prominent forehead, a narrow chin, a small jaw, and downturned corners of the mouth, clinodactyly (unusual curving of the fifth finger), asymmetric or uneven growth of some parts of the body and digestive system abnormalities, microdontia, blue sclera, increased risk of delayed development, speech and language problems and learning disabilites

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19
Q

What are the maternal risk factors for SGA infants?

A

hypertension, anemia, chronic renal disease, severe uncontrolled diabetes, malnutrition

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20
Q

What are the uteroplacental risk factors for SGA infants?

A

placenta previa, chronic abruption, placental infraction, multiple gestation

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21
Q

What are things to look for for antenatal diagnosing of IUGR?

A

fundal height measurement at prenatal visits (although poor screening tool), assessment of fetal motion, sonogram-sonographer action: alert physician, carefully evaluate placenta and fetal anatomy, determine cause, assess umbilical artery doppler for increased resistance to flow

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22
Q

What is the clinical sign for IUGR?

A

decreased fundal height and fetal motion

also grade 3 placenta before 36 weeks or decreased placental thickness

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23
Q

What are sonographic evaluations for IUGR?

A

BPP, NST (nonstress test), OCT (oxytocin challenge test)

assess umbilical artery doppler for increased resistance to flow

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24
Q

Describe diagnostic sonographic criteria for IUGR.

A

BPD (used alone is poor indicator of IUGR)
HC to AC ratio is useful in determining type of IUGR
FL may decrease in size with symmetric IUGR
AC is single most sensitive indicator of IUGR

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25
Q

What is the best indicator of IUGR? Why?

A

AC measurement
it determines liver size
an IUGR fetus will have a small liver because it is not storing nutirents

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26
Q

How do you determine the fetal weight?

A

most reliable estimated fetal weight formulas incorporate several fetal parameters, such as BPD, HC, AC, and FL

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27
Q

An AFI of what may represent IUGR?

A

less than 5cm

after 24 weeks

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28
Q

What size amniotic fluid pocket amy represent IUGR?

A

less than 1 to 2 cm

prior to 24 weeks

29
Q

Is it true that all oligohydramnios is associated with IUGR?

A

no

30
Q

What will a umbilical cord doppler show in the case of IUGR?

A

decreased, absent, or reversed diastolic flow

this is concerning and is associated with high risk of intrauterine fetal demise, thus, eary delivery

31
Q

How do you calculate the RI?

A

maximum systolic velocity - diastolic velocity / systolic velocity

32
Q

How do you calculate the systolic/diastolic ratio?

A

maximum systolic velocity / diastolic velocity

33
Q

How do you calculate the pulsitality index?

A

maximum systolic velocity - diastolic velocity / mean velocity

34
Q

How do you calculate acceleration time?

A

time from begining of systole to peak systole

35
Q

How do you calculate the deceleration time?

A

time from peak systole to end diastole

36
Q

What five biophysical parameters are assessed during an exam?

A 
cardiac nonstress test
observation of fetal breathing movement
gross fetal body movements
fetal tone
amniotic fluid volume
37
Q

What score for BPP is concidered concerning?

A

score of less than 6 is concerning

38
Q

What are the conditions for detecting fetal breathing movements?

A

one episode of breathing lasting 30 seconds

39
Q

What are the conditions for detecting gross movements?

A

3 discrete body or limb movement
unprovoked
continuous movement for 30 minutes should be counted as one movement

40
Q

What are the conditions for detecting fetal tone?

A

should be active extension and flexion of one episode of limbs or trunk

41
Q

What are the conditions for the non-stress test?

A

aka fetal heart rate
at least two episodes of fetal heart rate changes of 15 bpm and at least 15 second duration in 20 minute period
gross fetal movements noted over 20 minutes without late decelerations

42
Q

What are the conditions for AFI?

A

one pocket of amniotic fluid at least 2cm in two perpendicular planes or AFI total fluid measures of 5 to 22cm

43
Q

What is macrosomia?

A

birth weight of 4,500g or greater or above 90th percentile for estimated gestational age

with respect to delivery, any fetus too large for pelvis through which it must pass is macrosomia

44
Q

What is the most common risk factor for macrosomia?

A

diabetes

macrosomia is common result of poorly controlled maternal diabetes

45
Q

What are other risk factors for macrosomia?

A

diabetes, multiparity (secondary), maternal age 35 or older (secondary), maternal obesity pre-pregnancy weight of >70kg, PI in upper 10%, pregnancy wight gain of greater than or equal to 20kg, postterm pregnancy, have history of delivering LGA fetus

46
Q

What are the grades for BMI?

A

grade 1: overweight 25-29.9 kg/m2
grade 2: obesity 30-39.9 kg/m2
grade 3: mobid obesity greater than or equal to 40 kg/m2

47
Q

What BMI is associated with larger infants at delivery?

A

BMI greater than 30 kg/m2

48
Q

How do you calculate BMI?

A

body mass divided by the square of body height

49
Q

How much weight should a woman gain during pregnancy?

A

normal BMI: 11.2-15.9kg (25-35lbs)

overweight: 6.8-11.2kg (15-25lbs)
obese: 6.8kg (15lbs)

50
Q

What can reflect an increased AC?

A

adipose tissue, liver, heart, adrenal glands are disproportionately increased in size

51
Q

What does a macrosomic fetus have an increased incidence in?

A

morbidity and mortality as a result of head and shoulder injuries and cord compression

also increased incidence of maternal injury and c-section delivery

52
Q

What are two terms relating to macrosomic fetuses?

A

mechanical and metabolic microsomia

53
Q

What are the three types of mechanical macrosomia?

A

fetuses generally large(result from genetic factors, prolonged pregnancy, or multiparity)
fetuses generally large but with especially large shoulders(found in diabetic pregnancy)
fetuses with normal trunk but large head(caused by genetic constitution or pathologic process)

54
Q

What effects does macrosomia have on the placenta?

A

placentas can become significantly large and thick because not immune to growth-enhancing effects of fetal insulin

55
Q

What placental thickness is considered thick?

A

greater than 5cm

56
Q

What can be see in diabetic mothers?

A

polyhydramnios

57
Q

Describe the difference between symmetric and asymmetric IUGR?

A

symmetric IUGR is when the fetus is proportionally small and asymmetric IUGR is when the fetus head is larger than the rest of the body (commonly head sparing is seen)

58
Q

What is head-sparing theory?

A

results in 2nd trimester

the fetal body shunts blood to the brain and as a result, the rest of the body is smaller

59
Q

What are the five parameters of a biophysical profile? How are the scores assigned?

A

gross fetal movements, fetal tone (flexion/extension), breathing, AFI, and cardiac nonstress test
each variable is worth 2 points

60
Q

What is gradual hypoxia concept?

A

hypoxia is oxygen deficiency
early developing centers are less sensitive to hypoxia, so if there is damage (fetal tone), then there was severe hypoxia early in pregnancy
later developing centers are very sensitive to hypoxia, so if there was damage (cardiac activity), there was mild exposure to hypoxia later in pregnancy

61
Q

What are normal S/D values for the umbilical and maternal uterine arteries?

A

S/D ratio of >3.0 is abnormal for umbilical artery

S/D ratio of >2.6 is abnormal for maternal uterine artery and signifies a decrease of blood flow to the uterus

62
Q

Define macrosomia. Why is it a concern for the obstetrician?

A

When the fetal birth weight is greater than or equal to 4500g
With macrosomia, the fetus will be too large to deliver naturally and could cause injury to itself or mother

63
Q

How is macrosomia index being calculated?

A

Chest circumference minus (-) the BPD

64
Q

What changes do you expect to see in placenta of macrosomic fetus?

A

large and thick placenta

thick placenta being over 5cm thick

65
Q

Can asymmetric growth restriction be diagnosed if the fetus has been scanned once at 12 week?

A

no

it begins late in second or third trimetser

66
Q

Discuss three ways to detect fetal breathing.

A

kidney movement in sagittal plane
watching the diaphragm
spectral doppler at fetus nose to see fluid movement

67
Q

What is a normal AFI?

A

one pocket of fluid measuring at least 2cm in two planes or AFI total volume measures 5-22cm

68
Q

What is tha hallmark for IUGR?

A

fetal wasting

OB (10 decks)

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