Isthmocele: prevalence and clinical impact on menstrual bleeding patterns.

OBJECTIVE To determine the prevalence of isthmocele and its clinical impact on menstrual bleeding patterns.

MATERIALS AND METHODS A cross-sectional study was conducted from June 2023 to May 2025 at the Department of Obstetrics and Gynaecology, University of Campinas Medical School, Campinas, Brazil. Non-pregnant women aged 18-43 years with at least one caesarean delivery performed ≥6 months before enrolment and who were not using hormonal contraceptives or any kind of intrauterine devices were included. Participants completed a sociodemographic questionnaire, including caesarean-birth exposure collected retrospectively and a 90-day bleeding diary recording cycle interval, bleeding days, and flow intensity. All women underwent transvaginal ultrasound to assess the presence of isthmocele. Factors associated with isthmocele were examined using bivariate and multivariate logistic regression analyses.

RESULTS Of 301 participants, 126 (41.9%) had an isthmocele and 82.5% (104/126) of them were symptomatic. Compared with women without the defect, those with isthmocele, were older (p = 0.005) had a higher number of pregnancies (p = 0.044), previous caesarean deliveries (p = 0.026), ≥8 days of menstrual bleeding (p = 0.002), chronic pelvic pain (p = 0.024), uterine volume of 90-109 cm³ (p = 0.021), anteroposterior diameter ≥40 mm (p = 0.018) and endometrial thickness ≥4.7 mm (p = 0.021). Women with symptomatic isthmocele exhibited defects with greater length, depth and width, as well as a thinner residual myometrium (p < 0.001), when compared to asymptomatic women.

CONCLUSION Isthmocele was associated with advanced maternal age, multiple caesarean deliveries, and larger uterine and isthmocele dimensions. Symptomatic cases were more likely in women with larger defects, whereas greater residual myometrial thickness was associated with fewer symptoms.

SHORT CONDENSATION Advanced age, multiple caesarean deliveries, chronic pelvic pain, and prolonged menstrual bleeding appear to be associated with the presence of isthmocele.