P-314 Quantitative analysis of uterine peristalsis using optical flow for motion quantification

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Abstract Study question Do women with adenomyosis have altered uterine peristalsis? Summary answer Women with adenomyosis have altered uterine peristalsis on transvaginal sonography (TVS), as measured using optical flow for motion quantification. What is known already Adenomyosis can reduce the chance of clinical pregnancy in women undergoing assisted conception, with altered uterine peristalsis proposed as a mechanism. Uterine peristalsis can be visualised by TVS and is thought to play an important role in sperm transport and embryo implantation. Ultrastructural myometrial abnormalities in adenomyosis cause a disturbance in normal myocyte contractility with subsequent loss of normal rhythmic contraction. We aimed to develop an objective tool to quantify uterine peristalsis on TVS using an algorithm based on optical flow for wave motion quantification in women with adenomyosis. Study design, size, duration Prospective observational cohort study, July - December 2021, of women with moderate/severe adenomyosis (n = 16) and a normal pelvis (n = 21), having TVS during assisted conception. TVS was performed in the mid-sagittal plane for 4 minutes at baseline (BL), day 6-12 of ovarian stimulation (OS) and day of embryo transfer (ET). Recordings were stored offline for analysis using 3D Slicer (Ver. 4.11) and sampled at constant intervals to achieve a set of frames for optical flow analysis. Participants/materials, setting, methods We recruited women with moderate/severe adenomyosis or normal uterus on TVS. Optical flow was used to track pixels over successive TVS frames. Pixel-level displacements for points at endometrial-myometrial junction were used to compute time-period(inverse of frequency, 1/f) and amplitude(u) by fitting to the 2D-wave equation. Fit error was taken as a measure of coordination of wave at endometrial-myometrial junction(uterine peristalsis - up). Myometrial zone standard deviation quantifies spread, a measure of coordination of myometrial contractility(mc). Main results and the role of chance The observed wave of uterine peristalsis (up) at the endometrial-myometrial junction in women with adenomyosis showed a significantly poorer fit with the ideal wave equation compared to women with a normal uterus at all time points (BL (+ 0.725), OS (+ 0.612) and ET (+ 0.627) (n = 37, p < 0.001)), indicating lower coordination of uterine peristalsis in women with adenomyosis compared to women with a normal uterus. Coordination of myometrial contractility was also significantly lower in women with adenomyosis compared to women with a normal uterus at all time points (BL (+ 0.656) , OS (+ 0.510) and ET (+ 0.639) (n = 37, p < 0.001). Statistically significant difference was not found in wave amplitude or frequency between groups (p > 0.06 for both). Limitations, reasons for caution Optical flow for motion quantification has been used here to quantify uterine peristalsis in women with adenomyosis and women with a normal uterus and would require validation prior to use in other uterine pathology. Wider implications of the findings Women with adenomyosis have altered uterine peristalsis and myometrial contractility, which may account for their reduction in chances of conception. The proposed approach for wave motion quantification is an objective tool to quantify uterine peristalsis, with potential for wide clinical application in the gynaecology and assisted conception setting. Trial registration number Not applicable