Preimplantation 3D ultrasound: current uses and challenges.

The preimplantation ultrasound (US) refers to targeted imaging of the uterus and adnexa prior to assisted reproductive techniques (ART) to optimize the infertility treatment outcomes. After a thorough evidence based literature review, we propose the use of transvaginal three-dimensional (3D) US during the early follicular phase. A systematic approach for 3D US examination consists of a detailed examination of the uterine shape, size and contour, evaluation of the endometrial thickness, volume, pattern and vascularity, and assessment of the junctional zone regularity, echogenicity and thickness. Uterine anatomy is explored in the coronal plane by simultaneous visualization of the uterine cavity, the external surface of the fundus and cervix. Saline infusion sonogram (SIS) is recommended for patients with increased endometrial volume, abnormal endometrial pattern and irregular uterine cavity shape suggestive of Müllerian duct anomalies or acquired intracavitary abnormalities. Myometrial lesions should be recognized and proper dimensions and locations should be ascertained. Ovarian dimensions and volume are measured and the antral follicle count is recorded. Adnexa are carefully assessed for masses, endometriosis and dilated tubes. Color power Doppler US may be applied to evaluate vascularity of the ovaries and pelvic lesions. Hysterosalpingo-contrast-sonography (Hy-Co-Sy) should be optimally utilized for assessment of tubal patency. Accessibility and mobility of the ovaries should be checked in real time for better planning of the ultrasound-guided oocyte retrieval. The cul-de-sac is assessed for the presence of free fluid or masses.