Association Between Transvaginal Ultrasound Measurement of Endometrial Thickness With Serum Estrogen Level in Post-menopausal Women in a Tertiary Care Centre

Background Estrogen plays a vital role in endometrial physiology, and its deficiency in postmenopausal women leads to endometrial atrophy. However, residual or elevated estrogen levels - endogenous or exogenous - can stimulate endometrial thickening, which may signal an underlying pathology. Transvaginal ultrasound (TVUS) offers a non-invasive, practical method to measure endometrial thickness (ET), potentially serving as a surrogate marker for systemic estrogen exposure. This prospective observational study aims to correlate serum estradiol levels with endometrial thickness in postmenopausal women and to analyze the association between endometrial thickness and known estrogen-related risk factors. Methods A total of 100 postmenopausal women attending the gynaecology outpatient department at Sree Balaji Medical College and Hospital, Chennai, over a span of two years, from 2023 to 2025, were evaluated using TVUS for endometrial thickness and serum assay for estradiol levels. Baseline characteristics and comorbid conditions such as obesity, diabetes mellitus, hypertension, and parity status were recorded. Statistical analysis was used to assess correlations and significance. Results The mean endometrial thickness was 6.1±2.3 mm, and the mean serum estradiol level was 24.8±9.6 pg/mL. A moderate to strong positive correlation (r=0.78, p<0.001) was observed between serum estradiol levels and endometrial thickness. Endometrial thickness >4 mm was significantly associated with obesity (p=0.003), diabetes mellitus (p=0.005), and nulliparity (p = 0.008), but not with hypertension (p=0.082). Conclusion Serum estradiol levels may act as a surrogate biochemical marker for increased endometrial thickness in postmenopausal women. While elevated estrogenic activity can contribute to endometrial proliferation, increased endometrial thickness should not be interpreted in isolation as a direct indicator of high estrogen levels. Integrating serum hormone evaluation with TVUS findings and clinical risk profiling may enhance the early identification of women predisposed to estrogen-related endometrial pathology, particularly in postmenopausal care settings.