Ultrasonographic Evaluation of Endometrial Receptivity and Its Association with Clinical Pregnancy Rates in Subfertile Women

Background: Endometrial receptivity plays a decisive role in implantation, and advanced ultrasonographic parameters may non-invasively predict clinical pregnancy outcomes in women with subfertility. Objective: To assess structural and vascular ultrasonographic markers of endometrial receptivity and examine their independent and combined associations with clinical pregnancy rates in subfertile women. Methods: This prospective observational investigation was conducted at a 100-bedded district hospital in Narsingdi between January 2023 and December 2024. The study sample comprised 114 subfertile women who underwent mid-luteal transvaginal ultrasonography. Endometrial thickness, pattern, volume, uterine artery Doppler indices, and subendometrial blood flow were measured. Clinical pregnancy was confirmed by ultrasonographic visualization of a gestational sac. Results: Clinical pregnancy occurred in 41 women (36.0%). Mean endometrial thickness was significantly higher among pregnant women (9.8 ± 1.2 mm) compared with non-pregnant women (7.6 ± 1.4 mm; p < 0.001). A trilaminar endometrial pattern was observed in 78.0% versus 42.5%, respectively (p = 0.002). Endometrial volume was greater in conceived cycles (5.4 ± 1.1 cm³ vs 3.9 ± 1.3 cm³; p < 0.001). Subendometrial blood flow was detected in 85.4% of pregnancies compared with 51.3% of failures (p < 0.001). Mean uterine artery pulsatility index was significantly lower in the pregnancy group (1.82 ± 0.31 vs 2.34 ± 0.42; p = 0.004), while resistance index was also reduced (0.71 ± 0.05 vs 0.79 ± 0.06; p = 0.006). Conclusion: Integrated ultrasonographic assessment of endometrial morphology and vascularity demonstrates strong predictive value for clinical pregnancy and supports its routine use in evaluating subfertile women.