Quantitative characterization of uterine peristalsis propagation throughout the menstrual cycle using a novel intracavitary electrohysterography method

• IC-EHG allows objective assessment of peristalsis propagation characteristics • Two-thirds of uterine contractions are propagated; one-third are local events • Predominant propagation direction is F2C in mid-follicular, C2F in early luteal and bidirectional in late luteal phase • Propagation velocity is highest in the mid-follicular phase and lowest in the late luteal • Long recordings are required to avoid biased assessment of peristaltic propagation What are the characteristic propagation patterns of uterine contractions during the menstrual cycle in fertile women as assessed by intracavitary electrohysterography (IC-EHG). A prospective, multicentre cohort study was conducted at IVI clinics in Madrid, Barcelona and Valencia (Spain). The frequencies of occurrence of propagations (wavefront/min), their direction (cervix to fundus [C2F], fundus to cervix [F2C], opposing or random) and their velocity were measured. Features were extracted from 30 min IC-EHG recordings performed during the mid-follicular, early luteal and late luteal phases. Forty-three women were enrolled, and 113 recordings were suitable for inclusion in the analysis. Participants were aged 18–39 years and had proven fertility, regular menstrual cycles and a body mass index of 18.5–27.0 kg/m². Exclusion criteria comprised pregnancy, recent intercourse or hysteroscopy, uterine abnormalities, hormonal treatments and other relevant gynaecological conditions. Approximately two-thirds of the contractions detected by IC-EHG belonged to propagated wavefronts, while the remaining one-third were non-propagated (local) contractions. The highest frequency of propagated events was observed in the early luteal phase. The uterine peristalsis exhibited transient short-term clusters of wavefronts with the same propagation direction that shifted over time. F2C waves prevailed in the mid-follicular phase, C2F in the early luteal phase, and bidirectional activity in the late luteal phase. C2F wavefront propagation velocity was similar to that of F2C, which was higher in the mid-follicular phase than the late luteal phase. IC-EHG allows an objective assessment of uterine contraction propagation. The uterus manifested phase-dependent peristaltic propagation patterns in accordance with its specific physiological function. Short recordings (3–5 min) can bias the assessments of propagation patterns.