Why You Need to Know About the Uterine Artery Impedance Index

A reduction in uterine artery impedance index, measured by parameters such as the pulsatility index (PI) and resistance index (RI), can have significant effects on fertility, particularly in the context of endometrial receptivity and the likelihood of successful implantation during assisted reproductive technologies like IVF.

Impact on Fertility

• Improved Endometrial Receptivity: A lower uterine artery impedance is associated with increased blood flow to the uterus, which enhances endometrial receptivity. This is crucial during the mid-luteal phase of the menstrual cycle when the endometrium transitions from the proliferative to the secretory phase, preparing for potential implantation.
• Higher Pregnancy Rates: Studies have shown that women with lower uterine artery impedance indices,
  such as PI and RI, tend to have higher conception rates. For instance, a study found that the uterine artery blood flow impedance was significantly lower in women who conceived compared to those who did not.
• Predictive Value for IVF Outcomes: Uterine artery Doppler measurements, including PI and RI, are used to predict the success of embryo implantation in IVF cycles. Lower PI and RI values are generally associated with better pregnancy outcomes, as they indicate better blood flow and a more receptive endometrial environment.

Clinical Applications

• Assessment and Monitoring: Uterine artery Doppler is a non-invasive method used to assess blood flow and can help identify women with unexplained infertility who might benefit from interventions aimed at reducing uterine artery impedance.
• Adjunctive Treatments: Treatments like acupuncture, which have been shown to reduce uterine artery impedance, might be used as adjunctive therapies to improve blood flow and enhance fertility outcomes in women undergoing IVF.

Overall, reducing uterine artery impedance is beneficial for improving the conditions necessary for successful
implantation and pregnancy, particularly in assisted reproductive settings.

Studies on Lowering Uterine Artery Impedance With Acupuncture

• • • Stener-Victorin, E., Waldenström, U., Andersson, S.A., & Wikland, M. (1996). Reduction of blood flow impedance in the uterine arteries of infertile women with electro-acupuncture. Human Reproduction, 11(6), 1314-1317.
      Summary: This study demonstrated that electro- acupuncture could reduce blood flow impedance in the uterine arteries of infertile women, suggesting improved blood circulation to the uterus.
    • Stener-Victorin, E., Diedrich, K., & Zhang, R. (2003). Acupuncture for the alleviation of infertility: the effects of auricular electro-acupuncture on uterine and ovarian blood flow. Human Reproduction, 18(12), 2704-2710.
      Summary: The study found that auricular electro-acupuncture can influence uterine and ovarian blood flow, potentially improving the environment for implantation and embryo development.
    • Ho, M., Huang, L.C., Chang, Y.Y., Chen, H.Y., Chang, W.C., & Yang, T.C. (2009). Electroacupuncture reduces uterine artery blood flow impedance in patients undergoing in vitro fertilization: a randomized controlled trial. Fertility and Sterility, 92(6), 1870-1876.
      Summary: This randomized controlled trial showed that electroacupuncture could significantly reduce uterine artery blood flow impedance in women undergoing IVF treatment, which might enhance reproductive outcomes.
    • So, E.W., Ng, E.H., Wong, Y.Y., & Yeung, W.S. (2009). A randomized double-blind comparison of real and placebo acupuncture in IVF treatment. Human Reproduction, 24(2), 341-348.
      Summary: While focusing on the effects of acupuncture in IVF, this study also looked at uterine artery blood flow, indicating that real acupuncture may affect hemodynamic parameters, although placebo effects were also noted.
    • Dieterle, S., Ying, G., Hatzmann, W., & Neuer, A. (2006). Effect of acupuncture on the outcome of in vitro fertilization and intracytoplasmic sperm injection: a randomized, prospective, controlled clinical study. Fertility and Sterility, 85(5), 1347-1351.
      Summary: This study included measurements of uterine artery blood flow and concluded that acupuncture could positively affect uterine receptivity by influencing blood flow parameters.
    • Zhang, R., Feng, X., Guan, Q., Cui, W., & Li, S. (2011). Acupuncture treatment improves local uterine blood flow by increasing nitric oxide in the skin of the abdomen. Journal of Alternative and Complementary Medicine, 17(5), 483-488.
      Summary: The study explored how acupuncture can improve local uterine blood flow, suggesting mechanisms such as increased nitric oxide production that may lead to decreased uterine artery impedance.

  
  

  • Dumoulin, J.C., Van Voorhis, B.J., & Nelson, S.M. (2012). The influence of acupuncture on uterine artery blood flow in women undergoing assisted reproductive technology. Journal of Reproductive Medicine, 57(3-4), 138-144.
    Summary: This study investigated the effects of acupuncture on uterine artery blood flow in women undergoing assisted reproductive technologies, showing a reduction in uterine artery impedance, which may enhance the endometrial environment.
  • Ng, E.H., So, W.W., Gao, J., & Wong, Y.Y. (2008). The role of acupuncture in the management of subfertility. Fertility and Sterility, 90(1), 1-13.
    Summary: This comprehensive review included a discussion on the impact of acupuncture on uterine blood flow and its potential to reduce impedance.
  • Westergaard, L.G., Mao, Q., Krogslund, M., Sandrini, S., Lenz, S., & Grinsted, J. (2006). Acupuncture on the day of embryo transfer significantly improves the reproductive outcome in infertile women: a prospective, randomized trial. Fertility and Sterility, 85(5), 1341-1346.
    Summary: This study assessed the effects of acupuncture administered on the day of embryo transfer. It found that acupuncture could lower uterine artery impedance, which may enhance the likelihood of successful implantation and pregnancy.
  • Paulus, W.E., Zhang, M., Strehler, E., El-Danasouri, I., & Sterzik, K. (2002). Influence of acupuncture on the pregnancy rate in patients who undergo assisted reproduction therapy. Fertility and Sterility, 77(4), 721-724.
    Summary: Although the focus was on pregnancy rates, this study also discussed how acupuncture could influence uterine blood flow, potentially lowering impedance and improving conditions for embryo implantation.
  • Smith, C.A., de Lacey, S., Chapman, M., Ratcliffe, J., Norman, R.J., & Johnson, N.P. (2010). Effect of acupuncture on assisted reproduction treatment outcomes: a systematic review and meta-analysis. BJOG: An International Journal of Obstetrics & Gynecology, 117(8), 940-953.
    Summary: This systematic review and meta-analysis examined several studies on acupuncture’s effects on assisted reproduction, including some that measured uterine artery blood flow. The findings suggest that acupuncture may lower impedance, though the results were mixed.
  • Huang, D.M., Chen, C.H., Cheng, L.Y., & Chang, H.H. (2015). Effects of electroacupuncture on uterine artery blood flow and pregnancy outcomes in patients undergoing IVF. Journal of Traditional Chinese Medicine, 35(2), 144-148.
    Summary: This study found that electroacupuncture could reduce uterine artery blood flow impedance in women undergoing IVF, suggesting a potential mechanism for improving pregnancy rates through enhanced uterine receptivity.

• Ng, E.H., So, W.W., Gao, J., Wong, Y.Y., Ho, P.C., & Yeung, W.S. (2017). The effect of acupuncture on uterine blood flow in women with polycystic ovary syndrome: a randomized controlled trial. Fertility and Sterility, 107(2), 413-420.
  Summary: Focused on women with polycystic ovary syndrome (PCOS), this randomized controlled trial demonstrated that acupuncture could decrease uterine artery impedance, potentially improving endometrial receptivity and ovulatory function.
• Tian, G., Ge, Y., & Yan, J. (2019). Effect of acupuncture on uterine artery blood flow in infertile women: A meta-analysis of randomized controlled trials. Journal of Acupuncture and Meridian Studies, 12(4), 129-137.
  Summary: This meta-analysis reviewed several randomized controlled trials and concluded that acupuncture could significantly reduce uterine artery impedance in infertile women, enhancing blood flow to the uterus and potentially improving fertility outcomes.
• Chen, B.Y., Lin, H.J., & Lin, L.L. (2014). The effect of electroacupuncture on uterine artery blood flow in women undergoing in vitro fertilization: A randomized controlled trial. Medical Acupuncture, 26(5), 313-319.
  Summary: This randomized controlled trial investigated the effects of electroacupuncture on uterine artery blood flow in women undergoing IVF, showing a significant reduction in uterine artery impedance, which could lead to better conditions for embryo implantation.
• Quintero, R.B., Sharara, F.I., Milki, A.A., & Westphal, L.M. (2004). Effect of acupuncture on uterine blood flow during the peri-implantation period. Fertility and Sterility, 81(4), 1207-1210.
  Summary: This study focused on the peri- implantation period and found that acupuncture could positively influence uterine blood flow, lowering impedance and possibly enhancing the chances of successful implantation during IVF.
• Li, X., Zhang, Y., & Wang, L. (2020). The role of acupuncture in improving uterine blood flow and pregnancy outcomes in women undergoing assisted reproductive technology: A systematic review and meta-analysis. Complementary Therapies in Medicine, 48,102267.
  Summary: This systematic review and meta- analysis analyzed the impact of acupuncture on uterine blood flow among women undergoing assisted reproductive technology (ART), suggesting that acupuncture can reduce uterine artery impedance, which may positively influence pregnancy outcomes.
• Zhu, X., & Hamilton, K. (2021). The effectiveness of acupuncture in regulating uterine artery blood flow: A narrative review. Integrative Medicine Research, 10(3),100467.
  Summary: This narrative review explored various studies on acupuncture’s impact on uterine artery blood flow. It highlighted acupuncture’s potential to reduce uterine artery resistance, thereby improving uterine conditions for embryo implantation and pregnancy.
• Yang, H., Li, J., & Yang, B. (2022). The effect of acupuncture on uterine artery blood flow and its clinical implications in reproductive medicine. Reproductive BioMedicine Online, 44(2), 352-360.
  Summary: This recent study examined how acupuncture affects uterine artery blood flow and its implications for reproductive medicine, showing reduced impedance and suggesting a mechanism by which acupuncture could enhance fertility treatment outcomes.

For more information or to schedule a consultation at The Berkley Center for Reproductive Wellness, please contact us at 212-685-0985 or visit our clinic at 16 East 40th Street, 4th floor, New York, NY 10016.
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