Implantation of the fertilized ovum outside uterine endometrium:
The Fallopian tube contains blood (Fallopian tube hematoma), placenta (cytotrophoblast, syncitiotrophoblast) and fetus. Not always all these can be identified bioptically.
New placenta produces HCG and corpus luteum graviditatis develops, therefore corresponding endometrial changes develop as well: hypersecretory endometrium, AS phenomenon, decidual changes of endometrial stroma. However, these changes are not present in all cases of extrauterine gravidity. Therefore it is important to evaluate histologically all cases of abraded endometrium, when there was any suspition for gravidity. In case no unequivocal signs of gravidity are found (fragments of placenta or embryo), it is necessary to rule out extrauterine gravidity clinically (ultrasound, HCG levels).