Transvaginal ultrasonic assessment of endometrial growth in spontaneous and hyperstimulated menstrual cycles

Endometrial thickness and reflectivity were assessed by transvaginal ultrasound in both spontaneous and hyperstimulated menstrual cycles. Two groups of women with ovulatory cycles were examined; women in group 1 had unexplained infertility and women in group 2 were having artificial insemination by donor because of reduced spermatogenesis; a third group (group 3) comprised women with tubal infertility undergoing hyperstimulation for in-vitro fertilization. There was no difference in endometrial thickness or reflectivity between the three groups. A basic pattern of endometrial appearance common to all cycles was found, consisting of hypoechoic, isoechoic and hyperechoic images, occurring in the early follicular, late follicular and luteal phases, respectively. In all three groups a positive correlation was found between proliferative phase plasma oestradiol concentration and endometrial thickness. Group 1 r = 0.403, P less than 0.01; group 2 r = 0.439, P less than 0.01; and group 3 r = 0.617, P less than 0.01. There was a progressive increase in endometrial growth throughout the normal cycle until a plateau was reached 5 days after the LH surge. This pattern was also seen without acceleration of the process in hyperstimulated cycles, despite supranormal levels of oestrogen. Assessment of endometrial thickness is not a useful variable in monitoring hyperstimulated cycles. No aberrations of endometrial growth or pattern were observed in the women with unexplained infertility.