Advances in ultrasound assessment in the establishment and development of pregnancy.

Current data demonstrate that angiogenesis in the ovaries and uterus is an essential component of both follicular and luteal phases of menstrual cycle, tightly correlating with the levels of bioactive substances such as hormones, growth factors and interleukins. Ultrasound is used principally to demonstrate follicular growth, a receptive triple layer endometrium and to exclude pathologies such as fibroids and ovarian tumours. However, the development of new technologies such as CDI, CPA, 3D-US, 3D-CPA is now set to expand the role of ultrasound in the assessment of the processes in the ovaries, uterus and early pregnancy. There is growing evidence that studies of peri-follicular vascularity will predict the development of a healthy oocyte and subsequently an embryo. Endometrial blood flow studies with conventional CDI and the newer techniques of CPA and 3D-CPA will be important in predicting endometrial receptivity. Ovarian stromal vascularity appears to correlate with vascular endothelial growth factor (VEGF) levels and high vascularity is associated with PCO and a risk of ovarian hyperstimulation syndrome. 3D-CPA may improve our ability to assess ovarian and endometrial vascularization and blood circulation, to diagnose tubal patency. Increasingly, 3D ultrasound is being applied to diagnose the pathology of early singleton and multiple pregnancies.