P26.19: Thin endometrium as a possible reason of missed pregnancy

Abstract

We would like to present a case report of 5 patients who had missed pregnancy in the first trimester. All these patients had uterine curettage in our clinic and normal embryo karyotype was proved. In all this cases uterine curettage over time was followed by hysteroscopy and repeated curettage because of remains of chorionic tissue. One woman had hysteroscopy and repeated curettage for this reason twice: one time - after abortion and the second time - after delivery. In all these cases the removal of the chorionic debris was not performed easily, because of intense attachment to uterine wall. We retrospectively revised ultrasound examinations of these patients in the absence of pregnancy (some time before the missed pregnancy), before and after hysteroscopy and repeated curettage. It was found out that the endometrium of all these women in the late proliferative phase of menstrual cycle was quite thin - 4-6,4 mm maximum and normal three layer structure of endometrium was seen only in 2 patients. 4 of 5 patients had implantation in uterine corners or in the isthmus. On the echograms before and after hysteroscopy and repeated curettage Doppler signs of deep location of chorionic vessels were seen, in one patient the uterine wall abnormality extended to serous layer. We suggest the connection between thin endometrium and impaired process of chorion invasion and decidual formation (deep trophoblast invasion) especially in cases of low implantation and implantation in uterine corners where endometrium is known to be thinner and decidual formation is often impaired. It seems that some mechanisms of self-protection (uterine protection) are settled down in these cases and, as a result, termination of pregnancy occurs. Undoubtedly, this suggestion needs further investigation.