Purpose: Our purpose was to verify our earlier observation of an alter
ed endometrial echo character during the periimplantation period, sign
ifying the earliest detection of implantation by ultrasound. Methods:
The transvaginal ultrasound study used a 7.5-MHz probe on day 6 follow
ing preembryo transfer Results: Of 31 embryo transfers studied, 8 (25.
8%) were positive for this sign on day 6, whereas 9 patients later sho
wed a gestational sac, giving an accuracy of this sign of 88.8% (8 of
9) Conclusions: The normal secretory-phase endometrium shows a typical
, evenly distributed hyperechogenecity described earlier by Hackeloer
(1). In some cases of proliferative phases, too, this echo pattern has
been reported by others (2, 3), and observed by us in stimulated and
unstimulated cycles, and has been named type A endometrium by Gonen et
al. (4) Both these varieties are seen to have an even, unbroken outli
ne at the anterior and posterior myometrial-endometrial interphase. We
report what we believe to be the earliest ultrasound picture of impla
ntation, resembling this variety of endometrial echo bur having an irr
egular outline (Fig. 2).