INTRODUCTION

Ultrasound (US) measurement of the endometrium is now an indispensable part of ovulation induction monitoring and assisted reproductive technologies (ART). It also has a role in evaluation of unexplained infertility. Before ultrasound, the condition of the endometrium could only be evaluated by progesterone challenge to induce withdrawal bleeding or by invasive procedures, biopsy, curettage, and hysteroscopy. Endometrial physiology and implantation have recently been reviewed by Strowitzki et al. (1). This chapter will describe the use of US in the evaluation of infertility and monitoring ovulation induction for ART and for relations or artificial insemination.

ENDOMETRIAL EVALUATION

Endometrial Pattern

Evaluation of the endometrium in infertility was initially focused on its appearance or pattern and only later was the importance of endometrial thickness fully appreciated. Smith et al. (2) first reported use of the appearance and thickness of the endometrium to decide when to administer human chorionic gonadotropin to initiate ovulation (hCG). They classified endometrial patterns as Type A, a multilayered “triple-line” endometrium consisting of a prominent outer and central hyperechogenic line and inner hypoechogenic or black regions; Type B, an intermediate isoechogenic pattern, with the same reflectivity as the surrounding myometrium and a nonprominent or absent central echogenic line; and Type C, an entirely homogenous endometrium without a central echogenic line. Subsequently, Gonan et al. (3, 4) reversed the ABC order. The ABC classification is infrequently used in current literature.