Doppler ultrasonography and implantation: a critical review

Active perifollicular angiogenesis in ovaries and endometrium is linked with the quality of oocytes and endometrial receptivity, and consequently with the outcome of implantation. Studies evaluating ovarian velocimetry in relation to implantation and pregnancy rates bring essentially into play velocity values or non-quantitative parameters, whose reproducibility is low and which are hardly usable in daily practice. Conversely, the assessment of uterine artery flow by Doppler examination is easy and reproducible, and high impedance at the end of the follicular phase is a good predictive indicator of poor endometrial receptivity. In early pregnancy, Doppler investigation must not be used routinely because its safety is still under discussion; however, the available data show that impedance in the uterine and spiral arteries does not show any significant difference between normal and abnormal pregnancies (missed abortions or anembryonic pregnancies), and the significance of easily detectable intervillous flow is hotly debated, raising fundamental points.