P-424 Uterine contraction during implantation period; experience of 9,999 patients with 3 or more failure of embryo transfers

Abstract

Study question Is uterine contraction frequently observed in patients with recurrent implantation failure, and how is the frequency, direction, intensity and location? Summary answer Uterine contraction was frequently (41.3%) observed in patients with recurrent implantation failure mostly in the whole uterine cavity with “lower→upper→lower” direction. What is known already Uterine peristalsis caused by uterine contraction is thought to be one of the risk factors for implantation failure, because the uterus should be quiescent at the time of implantation period.Previous studies suggested more than 2 or 3 waves/min may be a threshold for implantation failure. Although those reports focused on frequency and direction of the uterine contraction, there were no reports regarding intensity and location of the uterine contraction. Therefore, we investigated intensity and location as well as frequency and direction of the uterine contraction in the largest number of patients with recurrent failure of embryo transfers. Study design, size, duration Transvaginal ultrasonography scans of uterine peristalsis were performed at the mid luteal phase in 9,999 patients with 3 or more failure of embryo transfers in two clinics between 2013 and 2024. The transvaginal probe (6 to 10 MHz) was introduced into the vagina as gently as possible to avoid stimulating the uterine cervix. After scanning mid-sagittal plane of the uterus, the probe was fixed as steady as possible while 3 min, video was recorded simultaneously. Participants/materials, setting, methods The video images were analyzed at 10 time the normal speed using Quick Time Player by a single observer. Frequency, intensity, location and direction of the uterine contractile activity were recorded and evaluated. Intensity was divided into 3 categories; movement with the whole endometrium (strong), with the middle and the surface of the endometrium (medium), and just the surface of the endometrium (weak). Direction was complicated with many patterns (e.g., lower→upper→lower). Main results and the role of chance Of 9,999 patients (average age, 37.4), 5,866 (58.7%) did not show any uterine contraction, 4,133 (41.3%) had uterine contraction. In the contraction group, frequency was 59.1% for 1 to 3 (times/3 min), 28.4% for 4 to 6, 10.1% for 7 to 9, and 2.4% for 10 or more. Intensity was almost equal among 3 categories (strong 25.1%, medium 41.6%, weak 33.3%). Most uterine contraction was observed in the whole uterine cavity (90.2%), whereas those in the upper, middle and lower part of the uterus were 5.0%, 0.7% and 4.1%, respectively. In terms of direction, most of uterine contraction was observed as “lower→upper→lower” (70.2%), followed by “upper→lower→upper” (9.9%), “upper→lower” (8.9%), “lower→upper” (8.4%), and unfocused (2.6%). Pregnancy outcome of patients (N = 36) who had strong uterine contraction with 10 or more was retrospectively evaluated after taking piperidolate hydrochloride (150 mg/day). Patients with live birth or ongoing pregnancy with 28 weeks or more were 18 (50.0%), those with biochemical pregnancy or miscarriage were 7 (19.4%), and those without pregnancy were 11 (30.6%). Limitations, reasons for caution Since this is a retrospective observational study, a prospective randomized study is necessary to determine the cutoff value that should be treated for uterine contraction in patients with recurrent implantation failure. Wider implications of the findings These data suggest that uterine contraction was frequently (41.3%) observed in patients with recurrent implantation failure, mostly in the whole uterine cavity with direction as “lower→upper→lower”. However, we have to determine the cutoff value that should be treated. Further studies will be required. Trial registration number Yes