Introduction: Implantation is one of the important stages in pregnancy which its defect can lead to ART failure. In fact, it is a critical event that can differentiate fertile and nonfertile cycles. Successful implantation depends on embryo quality & uterine receptivity. Several noninvasive methods are used for determining uterus receptivity during treatment cycles. One of these methods is transvaginal color doppler sonography. Factors such as endometrial thickness and pattern, myometrial contraction & echogenisity, uterine artery blood flow (measured as pulsatility index & resistance index) are evaluated by transvaginal color doppler sonography for evaluating uterine receptivity. The aim of present study was to evaluate whether uterine artery impedance, measured as PI and RI is related to outcome of ART cycles.
Material and Methods: In this prospective cross sectional study, infertile women aged <40 years old undergoing IVF/ET cycles were studied. This research was performed in Royan institute between 2003 and 2004. Exclusion criteria included: age >40 years and FSH>12. Patients were treated long standard GnRH agonist protocol. Evaluation of uterine arteries blood flow was performed about 1 hour before embryo transfer using color Doppler transvaginal sonography. Patients were at rest 20 minutes before sonography then transvaginal sonography was done one hour before ET in lithotomy posture with empty bladder. Uterine vessels were visualized with the color Doppler technique and the ascending branch was identified lateral to cervix at the level of internal os. PI (peak systolic velocity – peak diastolic velocity /mean velocity) and RI (peak systolic velocity – peak diastolic velocity /peak systolic velocity) were calculated on four consecutive uniform heart beats and averaged. According PI, patients were categorized as group 1(PI<2), group 2 (2?PI<3) and group 3 (PI?3). Anova & Tukey were used for analysis. P value less than 0.05 was considered as significant level.
Results: Three hundred ninety seven infertile women were studied. The mean age of them was 29.92±4.75 years. The mean PI and RI were 2.21±0.49 and 0.82±0.06, respectively. Three hundred fifty two women (89.6%) were suffered from primary infertility. Pregnancy occurred in 148 women (37.3%). One hundred twenty eight women (32.2%) were in group 1, 242 patients (61%) in group 2 and 27 women (6.8%) in group 3.The mean age in group 3 (28.59±5.38) was statistically lower than group 2 (29.61±4.73) and group 1 (30.8±4.55) (P=0.022).Also there was statistically significant difference between three groups in number of retrieved oocytes and number of transferred embryos (P<0.05).The chemical pregnancy rate was higher in group 2(40.2%) in comparison to group 1(35.9%) and group 3 (22.2%) but this difference was not statistically significant (P=0.17).
Discussion: In present study, chemical pregnancy rate was higher in women with 2?PI<3 and lower in patients with PI>3. In spite of lower age, the mean of retrieved oocytes and number of transferred embryos was lower in group 3 which can be suggested that patients with impaired uterine blood flow (high uterine artery PI), may have impaired ovarian flow too. It can be studied in further studies with evaluating ovarian & uterine blood flow simultaneously.
Conclusion: Ultrasonic measurements of PI of uterine artery on day ET can be helpful in predicting subsequent chemical pregnancy rate.