The relationship between aortic isthmus Doppler flow and other Doppler parameters was also assessed and is given in table 4.
There was significant association of retrograde diastolic aortic isthmus flow with abnormal umbilical artery, abnormal MCA, and abnormal DVdoppler.12/13(92.3%) cases of retrograde group had abnormal umbilical artery doppler flow (PI>95th centile or AREDF). Similarly 12/13(92.3%) cases of retrograde group had abnormal MCA Doppler flow (PI <2nd centile). 5/13 case of retrograde group had abnormal DV doppler (>95th centile). 5/7 (71.4%) of abnormal DV had reverse diastolic flow in the aortic isthmus.
The predictive value of the AoI and other Doppler parameters for an adverse perinatal outcome were also assessed.The predictive value of the AoI and other parameters for an adverse perinatal outcome is given in Table 5.
UA and AoI retrograde Doppler flow patterns and gestational age at delivery<34 weeks of gestation had the highest positive likelihood ratios. Abnormal AOI Doppler has 63% sensitivity, specificity of 87.5%, a good positive predictive value (92.3%) and positive likelihood ratio of (5) for the prediction of adverse perinatal outcome.
following equation of multiple regression analysis was used to see the relationship between Doppler variables and WOG with perinatal outcome -
Perinatal Outcome = 1.685 - (0.134 x UA) - (0.295 x MCA) - (0.097 x DV) + (0.164 x AOI) + (0.047 x WOG).
It stated that ,based on standardized coefficient, AOI (0.19) is the most important factor to extract perinatal outcome followed by WOG (0.047) .
Prematurity (delivery <34 weeks of gestation) alone has a sensitivity (70%) and high specificity (93%) and a high positive likelihood ratio (8.75) as a predictor of adverse perinatal outcome and overall mortality.
In the retrograde AOI group outcome was also assessed in two subgroups that is one with normal DV Doppler and another with abnormal DV Doppler (Table S1). No statistically significant difference was found in these two subgroups in terms of following parameters.
However, there was higher percentage of RDS (80%vs 38%) and NICU stay >7 days (100%vs 50%) in retrograde AoI group with abnormal DV Doppler. Also the only case with NEC had abnormal DVflow .Also perinatal mortality was higher (25%) in retrograde AoI group with normal DV.
This subgroup analysis of retrograde AoI group shows that the perinatal outcome can be adverse even when the DV flow is normal especially in terms of perinatal mortality.
There were total 18 cases in which weeks of gestation at delivery was <34 weeks.
Out of these majority (13) cases were delivered prematurely because of fetal indication that is abnormal Doppler and in only 5 cases maternal indication was present for delivery <34 weeks.
Analysis of the fetuses with AEDF or REDF in UA with retrograde AoI by sub grouping in those having normal DV and those with Abnormal DV was also done, shown in Table no. S2 .
It shows that, the group with normal DV did not require NICU admission for >7 days, while ¾(75%) cases with abnormal DV required NICU stay >7 days .There was 1 IUD and 1 NND from the group with normal DV. while 1 NND from DV abnormal group. So, even with normal DV Doppler flow the perinatal mortality (40%) was found in AEDF/REDF with retrograde AOI group with normal DV flow- P value 0.638 ,95% CI (-0.454-0.754)
Longitudinal changes in Doppler parameters in these IUGR fetuses are shown in figure 3 The median values for umbilical artery PI >95th centile ,Absent end diastolic flow (AEDF),Reverse end diastolic flow (REDF) ,Middle cerebral artery PI <5th centile ,Retrograde flow in aortic isthmus and DV Pi > 95 the centile were 8,1,0,7,2 and 0.5 respectively .