RESISTANCE INDEX OF UTERINE ARTERY AND PLACENTAL LOCATION IN INTRAUTERINE GROWTH-RETARDATION

Background. Our aim was to investigate the relationship between placen tal location and resistance index (RI) of uterine arteries in cases wi th intrauterine growth retardation (IUGR). Methods. Placental location and flow velocity waveforms of uterine arteries in 86 normal and 20 I UGR cases from 33 to 38 weeks of gestation were examined using a combi ned real-time scanner and pulsed Doppler ultrasonography. The location of placenta was classified as lateral when most of it was located to either the right or the left side of the uterine midline. Otherwise it was called central. Cases where the placenta was located in the uteri ne fundus or in the lower segment were not included. RI values were ca lculated from the uterine arteries on the placental side, on the non-p lacental side and in case of central placentas as a mean of both uteri ne arteries. In normal cases, the calculations were done every second week from 33 to 38 weeks of gestation, and the difference in variance among three gestational ages in each artery was tested by a one-way AN OVA. In IUGR cases, a standard deviation score (SDS) was calculated in dividually in each artery as (RI - normal mean)/normal SD. Differences in SDS between three categories of uterine arteries were examined by non-parametric tests. Results. In normal cases, there was no significa nt difference in variance of RIs among three gestational ages in each category of arteries. In IUGR cases, SDSs on the placental side were h igher than those on the non-placental side and those in central placen ta: (p<0.01, Wilcoxon's and Mann Whitney's tests, respectively). SDSs in five of eight cases with central placentas were below 1.0. Two of 1 2 cases with lateral placentas had higher SDSs on the non-placental si de than on the placental side and resulted in abruptio placentae. Conc lusions. Deviation of RIs in uterine arteries with IUGR could be affec ted by the pathologic conditions of the utero-placental blood flow on the placental side of lateral placenta rather than in central placenta and might be done by dramatic increase in resistance to flow of the m yometrial vessels on the non-placental side.