INFLUENCE OF EMBRYO IMPLANTATION ON ENDOMETRIUM IN LUTEAL PHASE OF MENSTRUAL CYCLE

Abstract

Background: Based on the facts known from embryology, rapid endometrial growth during late luteal phase of the cycle could be expected. In this research, we sought to establish if normal intrauterine pregnancy could be confirmed before gestational sac vizualization, by trans- vaginal ultrasound and hormonal tests. The primary hypothesis was that the endometrial thickness and/or volume in the luteal phase of the cycle, in cycles resulting in normal intra- uterine pregnancy, is significantly different compared to non-conception cycles. We also hypothesized that endometrial thickness and/or volume are different in cycles resulting in normal intrauterine pregnancy compared to cycles resulting in abnormal pregnancy, namely biochemical and ectopic pregnancy, and spontaneous abortion. Additionally, next to endometrial volumes, we decided to measure the endometrium in three planes (thick- ness, length and width), to see if the hypothesized endometrial volume differences could be approximated by this simple surrogate technique, which is available in most parts of the world.

Methods: This was a prospective observational study of women enrolled in an assisted reproduction program. Patients were stimulated with standard stimulation protocols. The oocyte retrieval was performed 36 hours after the hCG administration and the embryo was transferred 3 or 5 days later. Patients were first seen on day 20–24 of the cycle , and then on day 27–30 of the cycle. A blood sample was taken, and 3D transvaginal ultrasound was done. Following the completion of study visits, patients with a positive HCG test received phone call check- ups until week 12 of pregnancy, and were stratified according to pregnancy outcome.

Results: 80 subjects signed the informed consent form. 4 patients had the IUI in the stimulated cycle, one had ET in spontaneous cycle, and 74 patients had undergone IVF/ET in the stimulated cycle. 63 patients in the stimulated cycles completed the study and are included in the sta- tistical analysis presented here. Of these 63 patients, 36 (57.1 %) patients were pregnant, and of these 36, nine (25 %) had abnormal pregnancies that were analyzed separately. 27 (42.8 %) patients were not pregnant in the stimulated cycle. A significant difference was observed between Visit 1 and Visit 2, for endometrial volume, thickness, length and width in the pregnant group, and for endometrial volume, thickness and width in the non-pregnant group. Also, a significant difference was observed when comparing parameters at Visit 2 between pregnant and non-pregnant patients.

Conclusions: In this study we have shown that in normal intrauterine pregnancy after an IVF/ET, a rapid and prominent endometrial volume growth can be detected by a 3D ultrasound over the course of several days. Moreover, in patients who did not conceive in a particular cycle, a minimal to moderate decrease in endometrial volume can be seen in all patients. We have also shown that the changes in endometrial volume can be approximated by measuring the changes in endometrial thickness, length and width, which can be done on every ultrasound machine. Although it warrants further investigation, we believe these findings may prove useful in everyday practice and when there is uncertainty as to whether the pregnancy is normal or abnormal, and before gestational sac visualization.