جستجوی مقالات مرتبط با کلیدواژه "resistance index" در نشریات گروه "پزشکی"

Fetal hemodynamic changes can occur immediately following invasive chorionic villus sampling (CVS). We decided to study the possible effect of CVS on fetal heart rate (FHR), and uteroplacental resistance index (RI) changes using color Doppler ultrasound. Thirty-five pregnant patients with a gestational age of more than 12 weeks were included. Trans-abdominal CVS was done to assess the possibility of thalassemia. Before and after the CVS, color Doppler ultrasound was done to measure FHR and uteroplacental RI. Mean (SD) values for FHR before and after the CVS were 175.22 (±9) and 173.62 (±9.94) beats per minute, respectively; P=0.18. Mean (SD) uteroplacental RI before the CVS was 0.79 (0.07) which significantly increased to 0.82 (0.08); P=0.03. We observed a significant increase in resistance of blood flow in placental circulation after CVS. However, no significant change was observed regarding FHR after CVS.

Varicocele is one of the leading causes of infertility in men. Resistance index (RI) in testis is a parameter indicating parenchymal perfusion and microvascular functions. Increased RI in the testis of patients with varicocele might be a sign of impairments in microvascularization and a significant decrease in testicular perfusion. In the present study, RI in capsular and intraparenchymal testicular arteries was evaluated in patients with varicocele who underwent varicocelectomy.

This prospective cohort study was performed in 2019-2020 in Guilan, Iran. Sixty-six patients were included. Semen analysis was also done before surgeries. Patients with at least one disorder in semen analysis entered the study. RI in testicular arteries was measured by an experienced radiologist before surgeries. Six months after varicocelectomy, all patients underwent the same semen analysis and ultrasound imaging. Data were analyzed using SPSS software. The tests for analysis included McNemar Test and Wilcoxon and p<0.005 was considered as the significance level.

According to the results, 42 patients (63.6%) had positive changes in sperm analysis after surgeries. Sperm analysis showed a significant increase in number, concentration, morphology, and motility of sperm after surgeries (p<0.001). Further measurements of capsular and intratesticular RI in all patients also indicated a significant decrease (p<0.001).

Increased RI might be associated with impaired microperfusion in testis followed by impairments in semen. Moreover, mean capsular and intratesticular RI in patients decreased after surgeries and this decrease was significantly more in patients who had improvement in their semen parameters.

Doppler indices of umbilical artery are used as indicator of fetal well being.

To compare Doppler parameters of umbilical artery including pulsatility index (PI) and resistance index (RI) in patients with preeclampsia with those of normal pregnancies and to evaluate the diagnostic characteristics of these parameters in preeclampsia.

In a case control study, umbilical artery pulsatility and resistance indices were calculated at a free loop of umbilical cord in 25 preeclamptic patients and 75 uneventful pregnancies. Measurements were compared and diagnostic characteristics of the indices were determined.

Mean of pulsatility and resistance index were significantly higher in preeclampsia patients than the control group. Besides, patients with severe preeclampsia showed significantly higher values of PI and RI in comparison to those with mild preeclampsia. For PI, the cut-off of ≥0.98 yielded the highest sensitivity and specificity. Also, RI of 0.64 acquired a sensitivity of 100% and specificity of 44%.

Umbilical artery pulsatility index and resistance index increase in preeclampsia and these changes tend to be greater in severe preeclampsia. Umbilical artery PI and RI seem to be more appropriate in excluding preeclampsia rather than confirming it, and we propose the cut-off values of 0.98 for PI and/or 0.64 for RI, to rule-out the disease.