1. 1
Nir Melamed,1
Alex Pittini, 2
John Kingdom,1
Jon F.R. Barrett
1
Sunnybrook Health Sciences Centre, Toronto, ON, Canada. 2
Mount Sinai Hospital, Toronto, ON, Canada
Sonographic Factors Distinguishing Late Intrauterine
Growth Restriction from Late Small for Gestational Age
Fetuses
ABSTRACTABSTRACT
Distinguishing between constitutionally small for
gestational age (SGA) fetuses and those affected by
intrauterine growth restriction (IUGR) who are at risk of
adverse outcome presents an important challenge,
especially in cases of late IUGR. Our aim was to
identify sonographic factors that distinguish between
late IUGR fetuses and constitutionally SGA fetuses.
•Retrospective chart review at a single tertiary care
center from 2010-2015 of women with a singleton
pregnancy who delivered ≥32 weeks with a neonate
birth weight <10th
percentile for gestational age
•Neonates were classified as IUGR if they experienced
any of the following complications: perinatal mortality,
urgent Caesarean section for fetal distress, 5-minutes
Apgar < 7, umbilical artery pH < 7.1, need for
resuscitation or admission to NICU
METHODSMETHODS
OBJECTIVEOBJECTIVE
Identify sonographic factors that distinguish between
late IUGR fetuses and constitutionally SGA fetuses.
RESULTSRESULTS
•548 women met inclusion criteria,194 (35.4%) were in the late IUGR group (Table 1)
•CPR is the most predictive of the adverse outcome (Figure 3)
•Abnormal CPR values are more frequent in the IUGR group, with the Baschat gestational
age adjusted cut-offs giving the clearest distinction (Figure 4)
•CPR is useful to distinguish groups after 32 weeks (Figure 5)
•Multivariable model shows only CPR<5th
percentile (Baschat curve) as significantly
predictive with an adjusted odds ratio of 6.6 (2.8-15.6)
Characteristic Late
IUGR
group
N=194
Control
group
N=354
P Value
Characteristics
Nulliparity 140)72.2( 216) 61.0( 0.009
Pregnancy complications
Gestational diabetes 19)9.8( 18) 5.1( 0.04
Hypertensive complications 39)20.1( 32) 9.0( >0.001
Placental abruption 6) 3.1( 1) 0.3( 0.005
Placenta previa 5) 2.6( 1) 0.3( 0.014
Table 1. Study population characteristics
Figure 3. Adjusted odds ratios of sonographic
predictors of the composite adverse outcome
Figure 5. Average CPR values in control and IUGR
groups over the gestational period
Control
IUGR
Ebbings curve 5th
percentile
cut-off
Baschat curve
5th
percentile
cut-off
1.08 fixed
cut-off
Figure 4. Frequency of abnormal CPR measurements in control (black) and IUGR (red)
groups. Abnormality determined by three cut-offs based on nomograms and fixed cut-offs
from previous studies
CONCLUSIONSCONCLUSIONS
•Low EFW is a poor tool to assess IUGR fetuses
•CPR<5th
percentile is the best predictor of neonatal morbidity in IUGR fetuses
•Its use is effective after 32 weeks gestational age
•CPR may have predictive utility in other at risk groups
•Intrauterine growth restriction (IUGR) is associated
with higher neonatal mortality and morbidity
•Currently identified by low estimated fetal weight
(EFW)
•Doppler blood vessel studies have been proposed as
alternate identifiers of IUGR
•Umbilical artery Doppler-measures placental
resistance
•Middle cerebral artery Doppler-measures the “brain
sparing effect” seen in IUGR fetuses
•Cerebroplacental ratio (CPR) between the two is a
more sensitive measure of blood flow redistribution
than either alone (Figure 2)
•CPR is proposed as a better identifier of IUGR but
studies disagree on chosen cut-offs and utility in later
gestations
BACKGROUNDBACKGROUND
Figure 1. Sonographic
measurement of the middle
cerebral artery
Figure 2. Comparative rates of
change for sonographic
measurements
MCA PI<5th
%
UA PI>95th
%
EFW<3rd%
CPR<5th%
AC<3rd%