P-514 Uterine Contractility during Follicle Aspiration and Embryo Transfer and IVF/ICSI Outcomes: the WAVES study
Authors: Rees C , Huang Y , Thomas S , Klaassen C , De Boer A , Blank C , Christoforidis N , Humberstone A , Mischi M , Schoot B 
Published: June 2023

Study question

What is the influence of uterine contractility of in-vitro fertilisation (IVF) patients at follicle aspiration (FA) and embryo transfer (ET) on clinical pregnancy outcomes?

Summary answer

At time of embryo transfer, a lower contraction frequency, and increased contraction coordination is associated with more favourable chances of ongoing pregnancy after IVF/ICSI treatment.

What is known already

Uterine peristalsis is the rhythmic, wave-like motion of the subendometrial layer of the uterus. Various subjective methods using visual interpretation suggest that uterine peristalsis features are different in the various stages of the menstrual cycle, and they are thought to be important for fertility and early embryo implantation. Recently, a new automated quantitative method to measure uterine contractility was validated in a small number of IVF patients to analyse uterine peristalsis on transvaginal ultrasound (TVUS) recordings with speckle-tracking. With this method a new contraction feature – coordination – can be assessed alongside frequency, direction, amplitude.

Study design, size, duration

This study is part of an ongoing multi-centre prospective observational cohort study investigating uterine contractility on TVUS. Our study included patients undergoing IVF/ICSI treatment with good quality TVUS recordings from 2017 to 2023. Patients received fresh ET on Day 3 or Day 5.

Participants/materials, setting, methods

128 IVF/ICSI patients undergoing fresh ET were included from participating centres. Patients underwent TVUS within 1 hour prior to FA(n = 61/128), and/or within one hour before ET (n = 67/128). Uterine contraction frequency (CF), amplitude, velocity and coordination were measured by applying dedicated speckle tracking and strain analysis. The primary outcome was ongoing pregnancy (OP, viable pregnancy &gt;10 weeks gestational age). The independent T-test and Mann-Whitney U test were applied to compare features between groups.

Main results and the role of chance

39.1% of the IVF/ICSI patients (50/128) achieved ongoing pregnancy. Most patients underwent IVF/ICSI treatment due to a male factor (29.0%) or idiopathic subfertility (31.9%). Age, BMI and embryo quality were comparable for the pregnant vs. non-pregnant groups (p &gt; 0.05 for all). CF was significantly higher during FA vs. ET (1.70±0.26 vs. 1.54±0.23,[RC(1] p &lt; 0.001), as well as contraction velocity (0.79±0.22 vs 0.63±0.16, p &lt; 0.001). Contraction amplitude was also lower during ET vs. FA (0.06 IQR 0.03 vs. 0.08 IQR 0.04, p &lt; 0.001[RC(2] ). During FA, no significant differences were seen in contraction features for pregnant vs. non-pregnant groups (all p &gt; 0.05). At ET, a lower mean CF was significantly associated with OP(1.46 ±0.18 vs. 1.57±0.19 [RC(3] contraction/min, p = 0.016), as well as presence of more coordinated uterine contractions (0.22 ±0.09 vs. 0.33±0.14, p &lt; 0.001[RC(4] ). No significant differences were found for the features of amplitude and velocity.

Limitations, reasons for caution

Further validation of these results is ongoing, including expansion of the sample size. No sub-analysis has yet been done to assess the effect of additional IVF/ICSI treatment characteristics (i.e. stimulation protocol, type of subfertility) on uterine contractility and chance of pregnancy.

Wider implications of the findings

Uterine contractility changes its character depending on the timing of IVF treatment, with different characteristics seen at FA vs. ET. The most favourable contraction profile for ongoing pregnancy after ET seems to be uterine contractions with relatively low frequency and good coordination. These findings may support decision-making at ET.

Trial registration number

not applicable