Diagnostic value of ultrasound parameters in patients with chronic endometritis

Objective: to determine the diagnostic value of ultrasound features in chronic endometritis (CE) and identify the most significant features of the disease.

Materials and Methods. The study included 130 patients. The main group consisted of 98 women aged 23–45 years with infertility and recurrent pregnancy loss. CE was morphologically confirmed in all cases. The patients were divided according immunohistochemistry data into subgroups of CE with autoimmune component (n = 50) and CE without autoimmune component (n = 48). The control group included 32 women with normal endometrial morphology undergoing evaluation before assisted reproductive technology (ART) cycles due to male-factor infertility. Pelvic ultrasound was performed on days 6–9 and 18–23 of the menstrual cycle. From day 6 to day 9 of the cycle, the following ultrasound parameters were assessed: hyperechoic inclusions in the basal layer of the endometrium; an indistinct, irregular, or non-visualized endometrial midline; a hyperechoic endometrial midline; and free fluid in the uterine cavity. From day 18 to day 23 of the cycle, the following were evaluated: endometrial thickness, the vascularization coefficient of the uterine junctional zone, an indistinct outer endometrial contour, discordance between the endometrial structure and the menstrual cycle phase, and the presence of intrauterine synechiae. Factor analysis was performed to determine the significance of the aforementioned CE predictors in forecasting CE with and without an autoimmune component. The strength of the correlation coefficients was evaluated using the Chaddock scale. Subsequently, binary logistic regression was used to develop prognostic models for the probability of detecting various forms of CE for each of the identified features.

Results. According to the factor analysis results, the following features showed a strong correlation with chronic endometritis (CE): a vascularization coefficient of less than 20.9% and an endometrial thickness of less than 7 mm during the window of implantation (WOI). A moderate correlation was observed for the “indistinct outer endometrial contour” marker. All other features showed a weak correlation. Subsequently, binary logistic regression was used to develop prognostic models for the probability of identifying various forms of CE for each marker. For the detection of CE with an autoimmune component, the sensitivity and specificity of the model based on “endometrial thickness < 7 mm” were 84.4% and 80.0%, respectively; for the “vascularization coefficient < 20.9%” – 82.7% and 90.0%; and for the “indistinct outer endometrial contour”, 66.0% and 93.3%, respectively. In predicting CE without an autoimmune component, the sensitivity and specificity were: 38.5% and 88.2% for “endometrial thickness < 7 mm”; 68.7% and 87.5% for “vascularization coefficient < 20.9%”; and 61.0% and 84.0% for “indistinct outer endometrial contour”, respectively. Prognostic models based on features with weak correlation, such as discordance between the endometrial structure and the menstrual cycle phase or the presence of intrauterine synechiae, showed low sensitivity and specificity, often failing to reach statistical significance.

Conclusions. Among the ultrasound features of CE (both with and without an autoimmune component), the following demonstrated the highest predictive value: the vascularization coefficient of the uterine junctional zone, an endometrial thickness of less than 7 mm, and an indistinct outer endometrial contour during the window of implantation.

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