Resistance Index In Group Research Articles

Transvaginal color Doppler in the assessment of abnormal early pregnancy

The study groups comprised 61 pregnant women whose gestational age ranged from 7 to 12 weeks from the last menstrual period. All patients apparently had a normal developing pregnancy; there were no clinical symptoms of pathology e.g. bleeding in early pregnancy. Eighty-two patients with a clinically and ultrasonographically normal pregnancy whose gestational age ranged from 7 to 12 weeks, served as a control group. When the anatomical position of investigated area have been obtained clearly, pulsed wave Doppler sample volume was placed on the structures of interest: the both uterine arteries and intervillous space. There is no statistically significant difference between the Resistance Index (RI) in the left or right uterine artery (P greater than 0.01) and among investigated groups of patients (P greater than 0.01). The intervillous blood flow RI in the case of molar pregnancy was 0.38 with SD +/- 0.03; in blighted ovum 0.43 with SD +/- 0.03, and in missed abortion 0.43 with SD +/- 0.02. It should be stressed that in nine (31%) cases of blighted ova and in five (26%) cases of missed abortion, intervillous space flow could not be detected. In the control group, intervillous blood flow was always visualized and the mean RI was 0.45 with SD - 0.04. Statistical analysis showed significantly higher RI in control group in comparison with other groups of patients (P less than 0.01), and significantly lower RI in molar pregnancy in comparison with other groups of patients (P less than 0.01). There was no difference in RI between blighted ova and missed abortions (P greater than 0.01).

The effect of fetal heart rate on umbilical artery flow velocity waveforms.

Umbilical artery flow velocity waveforms were obtained using continuous wave Doppler ultrasound in 85 normal pregnancies (25 antepartum, 60 intrapartum) to examine the relation between fetal heart rate, end systolic/end diastolic ratio (A/B ratio) and resistance index (RI). Our results demonstrated a significant negative correlation between fetal heart rate, A/B ratio and RI (in the antepartum group r = -0.49, and in the labouring group r = -0.65). It is therefore important when performing mathematical analysis of umbilical artery flow velocity profiles to make a statistical allowance for fetal heart rate.