Endometrial and subendometrial vascularity are significantly lower in patients with endometrial volume 2.5 ml or less.

Endometrial development is largely dependent on a good blood supply to the basal endometrium. This study evaluated the endometrial and subendometrial vascularity in patients with thin (<or=8 mm) endometrium and in those with low volume (<or=2.5 ml) endometrium. Patients undergoing their first IVF cycle were recruited and all followed a standard ovarian stimulation regimen. Three-dimensional (3D) ultrasound examination with power Doppler was performed on the day of oocyte retrieval to determine endometrial thickness, endometrial pattern, Doppler flow indices of uterine vessels, endometrial volume and 3D power Doppler flow indices of endometrial and subendometrial regions. It was found that 3D power Doppler flow indices of the endometrial and subendometrial regions were significantly lower in patients with low volume endometrium compared with those with normal volume endometrium. The 3D power Doppler indices of the endometrial and subendometrial regions were comparable for patients with thin and normal endometrium. In conclusion, endometrial and subendometrial vascularity measured by 3D power Doppler ultrasound was significantly lower (P <or= 0.003) in patients with low volume endometrium, but not in those with thin endometrium.