Preliminary quantitative and qualitative evaluation of contrast-enhanced ultrasonography (CEUS) in normal proliferative endometrium of infertile patients.

Background: Numerous studies have suggested that assessing endometrial and subendometrial blood flow can contribute to the evaluation of endometrial receptivity. However, there remains a lack of unified expert consensus regarding the assessment of regional endometrial blood supply, and no established reference values are currently available for guidance. Using endometrial pathological biopsy as the gold standard, this study aims to characterize contrast-enhanced ultrasonography (CEUS) imaging features and establish reference ranges for quantitative parameters in the endometrium, subendometrial region, and myometrium during the normal proliferative phase in infertile patients, thereby providing reliable data to support the evaluation of endometrial receptivity. Methods: Infertile patients scheduled to undergo hysteroscopy and endometrial pathological biopsy at our hospital between April 2023 and July 2024 were enrolled. Relevant patient information was collected. All patients underwent CEUS examination prior to surgery, with pathological biopsy serving as the gold standard. The imaging features, qualitative indices, and reference ranges for the quantitative parameters of CEUS in the endometrium, subendometrium, and myometrium of patients with a normal proliferative endometrium were analyzed. Results: Following the inclusion and exclusion criteria, 40 infertile patients with normal proliferative endometrium were included in the study. The average thickness of the normal proliferative endometrium was 5.84±2.23 mm. The endometrial type was predominantly type B (29/39), and subendometrial blood flow was primarily type III (12/25). CEUS of the endometrial region was characterized mainly by uniform low enhancement (22/40) and uniform isointensity (14/40), with clear demarcation between the myometrium and subendometrium. The time-intensity curve (TIC) morphology was similar across the endometrial region, subendometrial region, and myometrium. The peak intensity (Pi) of the endometrial region was 16.19±4.28 dB, the ascending branch slope (K) was 0.24±0.09, the area under the curve (AUC) was 1,257.95±301.83 dB, and the time to peak (TtoPK) was 18.29±4.75 s. Good consistency was observed between different regions of interest (ROIs) measurements (10 mm × 1 mm Conclusions: CEUS of the normal proliferative endometrium in infertile patients mainly demonstrated homogeneous enhancement, predominantly low enhancement and isointensity, with clear boundaries between the subendometrium and myometrium, and distinct TIC characteristics. CEUS technology effectively displays the blood perfusion in the endometrium, subendometrium, and myometrium, with high sensitivity. This study provides reference ranges for the quantitative parameters of CEUS in the normal proliferative endometrium of infertility patients.