Main Findings-
There is a diversity and lack of uniform model which would reflect
hemodynamic changes in pregnancy with IUGR. The surveillance of these
IUGR cases and taking a clear cut decision whether to deliver these
fetuses or not and if when, thus weighing the risk of intrauterine death
by prolonging the gestation versus delivering the fetus prematurely is
the major concern. Our data call into question whether can be use
retrograde flow in aortic isthmus as a trigger to deliver these growth
restricted fetuses.
This study supports the association of retrograde flow in the aortic
isthmus with the adverse perinatal outcome as suggested by[13] M.Del Rio et al and Hidar et al[14]. In our study, Retrograde AoI group had
higher rates of adverse perinatal outcome (92.3% vs. 72%). Abnormal
AoI had sensitivity of 63.1%, a high specificity (87.5%) and a PPV
(92.3%) and likelihood ratio (5) for prediction of adverse perinatal
outcome. Overall perinatal mortality (intrauterine death and neonatal
death) was higher in retrograde group 3/13(23%).There was no perinatal
mortality in antegrade flow in AoI group. Thus suggesting a potential
role for Doppler imaging of the AoI in the clinical surveillance of
severe IUGR fetuses .
In our study, there was a highly significant association of retrograde
diastolic aortic isthmus flow with abnormal umbilical artery (92.3% vs.
36%) (p =0.013) similar to study by Del rio
etal[13] . Thus suggesting that retrograde
diastolic flow in the AOI represents a group with more severe and
earlier onset of placental insufficiency.
In a study by del rio et al[13] and Makikallio K
et al[15 ] , MCA vasodilatation did not differ
between the antegrade and retrograde groups .However in our study ,MCA
vasodilatation differed in the antegrade and retrograde groups (48% vs.
92.3%) respectively .
Similar to Del rio et al[13], our study shown a
strong association between the presence of abnormal DV flow and
retrograde flow in the AoI. (38% vs. 8%)( P= 0.034). 5/7(71.4%) of
cases with abnormal DV flow had reverse diastolic flow in the AOI. This
suggests well corelation of these parameters with the progressive
deterioration of cardiac function occurring in IUGR. All these findings
suggested significant corelation of retrograde flow in aortic isthmus
with abnormal flow in UA,MCA and DV.
Del rio et al[13] proposed that AoI PI and DV-PI
independently predict adverse outcome. And in preterm growth restricted
fetuses, AoI blood flow becomes abnormal on average 1 week before DV
blood flow does. In our study ,retrograde flow in AoI was seen on an
average 2 days before delivery and abnormal DV PI was seen 1 day before
delivery .
We have also analyzed, the fetuses with AEDF or REDF in UA with
retrograde AoI by sub grouping as, those having normal DV and those with
Abnormal DV .There were 2 perinatal deaths from the group with normal DV
while 1 NND from abnormal DV group . So , even with normal DV Doppler
flow the perinatal mortality (40%)was found in AEDF/REDF with
retrograde AOI group .Thus even though the DV flow is normal adverse
outcome might be suspected in fetuses with AEDF/REDF in UA and
retrograde flow in AoI. Thus providing a better window for delivering
the IUGR fetuses before failure of fetal compensatory mechanisms to
hypoxia.
Results –
Our study confirms previous observations that retrograde blood flow in
the AoI is associated with adverse perinatal outcome, particularly
intrauterine demise ,neonatal death ,RDS. Retrograde flow in AoI
correlates significantly with abnormal flow in Umbilical artery, Middle
cerebral artery and Ductus venosus.
Abnormal aortic isthmus flow is generally seen prior to abnormal changes
Ductus venosus Doppler .
Clinical Implications –
Even though the DV flow is normal adverse outcome might be suspected in
fetuses with AEDF/REDF in UA and retrograde flow in AoI. Thus providing
a better window for delivering the IUGR fetuses before failure of fetal
compensatory mechanisms to hypoxia.
Thus retrograde flow in AoI might be considered as an additional trigger
for delivering IUGR fetuses between 30-34 weeks with AREDF in UA.
Also , AoI Doppler might be considered as an additional clinical
parameter in the routine assessment of hemodynamically compromised
growth-restricted fetuses.