Transcript Ultrasound Evaluation of Fetal Growth

Fetal Growth Restriction
Steven R. Allen, MD
Scott & White Clinic
TAMU-HSC
Educational Objectives
• Review epidemiology and significance of
fetal growth restriction (FGR)
• Know etiologies (= risk factors)
• Discuss screening strategies for FGR
• Evaluate the role for Doppler velocimetry
in the diagnosis & mgmt of FGR
• Develop treatment strategies for FGR
Arbitrary threshold for
“growth restriction”
Weight
5000
4500
4000
3500
3000
2500
2000
1500
1000
500
0
90%
50%
10%
3%
22
26
30
34
Gest Age, weeks
38
42
Variables affecting normal
fetal growth*
•
•
•
•
•
Gender
Ethnicity
Number of fetuses
Altitude
Parental phenotype
* generally not accounted for in growth curves
Significance of fetal growth
restriction (FGR)
• 3-10% of newborns are “growth restricted”
• associated morbidities
• intrapartum FHR abnormalities
• cord blood acidemia
• cesarean delivery
• neonatal hypoglycemia, hypothermia,
and hyperbilirubinemia
• 1/4 stillbirths are SGA
FGR: neonatal morbidities
27-32 wks gestation
70
NS*
60
50
%
40
SGA (n=34)
AGA (n=132)
30
20
NS
10
0
NMR
RDS
Sepsis
IVH
(3/4)
*RDS: not benefited by FGR
NEC
AJ Perinat 2000;17:187
Long term implications of FGR
• Outcome related to
etiology - worse for
aneuploidy, viral infxn
• Catch-up growth
common
• Adult risks: HTN,
hypercholesterolemia
• Minimal reduction in IQ
not predictive of
academic achievement
IQ
Sev SGA
Mod SGA
AGA
120
100
80
60
40
20
0
Male
Female
J Pediatr 2001;138:87
Long term implications of FGR
Barker “thrifty phenotype”
hypothesis
• Fetus adapts to
malnutrition
– Cephalized blood flow
– Metabolic programming
beneficial to malnourished
fetus is detrimental if
adequate nutrition later
available
• Unknowns
– Molecular basis
– Relative roles of genetic &
environmental factors
RR
LBW vs heaviest
18
16
14
12
10
8
6
4
2
0
Gluc intol
Metab
synd
Ozanne. Online review. 9/12/02.
http://tem.trends.com
Pathophysiology of FGR
Cellular
Hyperplasia
Cellular
Hypertrophy
“symmetric”
1
“asymmetric”
Trimester
3
Etiology of FGR
fetal
idiopathic
fetal/mat
maternal
Etiology of FGR
“Symmetric”:
•infection (<5%)
•malformation
•aneuploidy
•low mat wt, wt gain
•multiple gest
•XR exposure
fetal
idiopathic
fetal/mat
maternal
Etiology of FGR
fetal
idiopathic
fetal/mat
“Symmetric”:
•tobacco
•alcohol
•substance abuse
•teratogens
maternal
Etiology of FGR
fetal
idiopathic
“Constitutionally
small”
fetal/mat
“Asymmetric”:
Placental
mosaicism
(up to 1/4)
maternal
•HTN
•renal dis
•thrombophilia
•hypoxia
•anemia
•advanced DM
•malnutrition
Prior IUGR as a predictor of
subsequent stillbirth
OR
Swedish birth registry 1983-1997
12
10
8
6
4
2
0
>37
32-36
<32
Wks gest age of prior SGA birth
Surkan. NEJM 2004;350;777-85
Defects in “classic” model of
FGR subsets
• Many preterm fetuses with growth
restriction secondary to maternal HTN
have symmetric FGR
• Many aneuploid fetuses have
asymmetric growth (“head sparing”)
Classification of FGR
symmetric
asymmetric
Abnormal metabolic parameters
seen in some populations with FGR
• Most FGR fetuses have normal PO2 & PCO2
• Hct & Hgb usually normal, with high MCV
and RDW (erythropoeisis/reticulocytosis)
• Inconsistent hypoglycemia
(& hypo-insulinemia)
• Increased ratio of non-essential:essential AA
• Hypertriglyceridemia
• Thrombocytopenia
Screening for FGR
Etiologies = risk factors
•
•
•
•
Fetal
Maternal-fetal
Maternal
Idiopathic
Screening for FGR
Physical exam
• Serial fundal height: between 1830 weeks, FH(+/- 2-3 cm) = EGA
in weeks
– sensitivity for FGR = 40-67%
– false pos rate = 50%
Screening for FGR
Ultrasonography
•
•
•
•
•
EFW
Abdominal circumference
Head:abdomen ratio
Serial measurements (rate of growth)
Amniotic fluid volume
Anatomic survey indicated if FGR detected
Screening for FGR
Ultrasonography
• 3rd TM AC sensitivity for FGR = 80% (no
different than sensitivity of FH)
• Reserve US for those pts at risk for FGR:
– risk factors
– S<D
– prior SGA
ACOG Prac Bull #12, 1/2000
Doppler velocimetry
Screening for FGR
• sensitivity in Low Risk population: 15-30%
• sensitivity in Hi Risk population: 75-95%
• commonly associated with FGR, but not
diagnositic
• NOT uniquely helpful
Doppler velocimetry: S/D ratio
S/D = 3.1
Doppler velocimetry
Management of FGR
• Umbilical artery: S/D ratio increases with
placental resistance
Umbilical artery in FGR
Doppler velocimetry
Management of FGR
• Umbilical artery: S/D ratio increases with
placental resistance
• Middle cerebral artery: S/D ratio decreases
with cephalization (“head sparing”)
Middle cerebral artery in FGR
Doppler velocimetry
Management of FGR
• Umbilical artery: S/D ratio increases with
placental resistance
• Middle cerebral artery: S/D ratio decreases
with cephalization (“head sparing”)
• Umbilical vein: becomes pulsatile with heart
failure
Umbilical vein in extreme FGR
Doppler velocimetry
Management of FGR
• Umbilical artery: S/D ratio increases with
placental resistance
• Middle cerebral artery: S/D ratio decreases
with cephalization (“head sparing”)
• Umbilical vein: becomes pulsatile with heart
failure
• Ductus venosus: decreased forward
velocity or reversal of “a” wave (atrial kick)
• Changes typically occur in this sequence
prompting a logical screening sequence
Ductus venosus in extreme FGR
“a” wave
FGR example 1
risk factor: tobacco
Weight
5000
4500
4000
3500
3000
2500
2000
1500
1000
500
0
90%
50%
10%
3%
22
26
Gest Age, weeks
30
34
38
42
Umb artery S/D nl
FGR example 1: mgmt
•
•
•
•
d/c tobacco
serial US
biophysical testing and FACs
delivery plan?
Umb art S/D predicts risk of
neonatal morbidity
35
30
%
25
20
15
10
5
0
AGA
SGA, nl S/D
SGA, abnl S/D
J US Med 2000;19:661
FGR example 2
risk factor: CHTN
Weight
5000
4500
4000
3500
3000
2500
2000
1500
1000
500
0
90%
50%
10%
3%
22
26
Gest Age, weeks
30
34
38
42
Umb artery S/D elevated
FGR example 2: mgmt
• MCA S/D ratio - minimally
decreased; normal umb venous
flow pattern
• R/O PIH
• serial US
• biophysical testing and FACs
• delivery plan?
Interventions with UNproven efficacy
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•
•
•
•
•
•
nutrient treatment
zinc supplementation
calcium supplementation
plasma volume expansion
oxygen
heparin
aspirin
FGR example 3
risk factor: AMA
Weight
5000
4500
4000
3500
3000
2500
2000
1500
1000
500
0
90%
50%
10%
3%
22
26
Gest Age, weeks
30
34
38
42
Oligohydramnios; umb art AED;
MCA S/D low; umb vn pulsatile
FGR example 3: mgmt
• Continuous monitoring
• Corticosteroids
• Delivery after 24 hrs if stable
Considerations for delivery
•
•
•
•
Non-reassuring acute fetal status
Cessation of growth over 2-4 wks
Oligohydramnios
“When extrauterine survival is likely
in the presence of significantly
abnormal antenatal testing”
ACOG Prac Bull #12, 1/2000
FGR: Summary Recommendations
(Level A)
• Umbilical artery velocimetry is useful
to reduce perinatal death once FGR
is suspected or diagnosed
• No specific treatments (nutritional
supplements, oxygen, heparin, ASA,
volume expansion, or
antihypertensive agents) effectively
prevent or treat FGR
ACOG Prac Bull #12, 1/2000
FGR: Summary Recommendations
(Level C)
• Antepartum surveillance should be instituted
when extrauterine survival is possible
• No particular form of antenatal testing is
superior
• Screen low-risk pts for FGR using physical
exam
• US is appropriate screen for FGR in hi-risk
pts
ACOG Prac Bull #12, 1/2000