[Correlation between uterine volume and intrauterine adhesion: a propensity score matching analysis]

Objective: To investigate the correlation between uterine volume and intrauterine adhesion (IUA). Methods: From June 2018 to November 2019, totally 7 007 patients who underwent hysteroscopy in outpatient operating rooms of Gynecological Minimally Invasive Center, Beijing Obstetrics and Gynecology Hospital were retrospectively analyzed. Patients of reproductive age with IUA without uterine fibroids and adenomyosis were selected as IUA group, and patients of reproductive age without uterine fibroids and adenomyosis without IUA during the same period were selected as the control group. The propensity score matching (PSM) method was used to perform 1∶1 matching for the two groups of patients, matching variables included age, height, weight, body mass index (BMI), gravidity, parity, and number of abortion curettage. Whether there was any difference in uterine volume between the two groups of patients was compared, and whether uterine volume was an influencing factor of IUA was explored. The patients in IUA group were also categorized into mild, moderate and severe to explore whether uterine volume influenced the severity of IUA. Results: (1) After inclusion and exclusion criteria, 351 patients were included in IUA group and 2 986 patients in the control group. With PSM, 327 patients in IUA group and 327 patients in the control group were finally enrolled in this study. There were no statistically significant differences in age, height, weight, BMI, gravidity, parity, and number of abortion curettage between the two groups of patients after matching (all P>0.05). (2) After PSM, there was a significant difference between the uterine volume of IUA group (median: 44.23 cm³) and the uterine volume of the control group (median: 57.20 cm³; P<0.001). (3) Reduced uterine volume (OR=0.961, 95%CI: 0.952-0.970) was an independent risk factor for IUA (P<0.001). (4) Uterine volume had a significant effect on the severity of IUA (P<0.001), the larger the uterine volume (B=-0.030, 95%CI: -0.044 to -0.017), the less severe the IUA. Conclusions: Reduced uterine volume is an independent risk factor for IUA, and uterine volume has a significant effect on the severity of IUA. In patients with small uterine volume size, primary and secondary prevention of IUA should be emphasized.