Significantly Elevated Uterine Artery Doppler Indices and Impaired Subendometrial Perfusion Characterise Infertile Women in a North-Eastern Nigerian Population: A Case-Control Study

Background: Objectives: This study aims to determine and compare uterine artery Doppler indices and subendometrial blood flow patterns between infertile and fertile parous women in Maiduguri, Nigeria, a region within Africa's high-prevalence infertility belt. Methods: This prospective case-control study was conducted over 13 months period involving 300 newly diagnosed cases of infertile women and 300 aged-matched fertile parous controls. Transvaginal Doppler ultrasound was performed during the mid-luteal phase. Uterine artery pulsatility index (PI) and resistivity index (RI) were measured, and subendometrial blood flow was classified into zones (1-4). Main Outcome Measures mean uterine artery Pulsatility Index, Resistivity Index, and distribution of subendometrial blood flow zones. Results: The mean age was 30.3±7.0 years for cases and 34.7±6.9 years for controls (p<0.001). Infertile women exhibited significantly higher uterine artery impedance: mean RI was 0.79±0.07 vs. 0.73±0.06 (p<0.001), and mean PI was 2.15±0.56 vs. 1.69±0.30 (p<0.001). Subendometrial perfusion was markedly reduced in the infertile group (p<0.001); while all controls (100%) displayed optimal Zone 3 flow, only 54.3% of infertile women did. Furthermore, 45% of infertile women had a clinically high RI (>0.8) compared to none in the control group. Conclusion: Infertile women in this population demonstrate significantly impaired uterine perfusion, evidenced by elevated Doppler indices and reduced subendometrial blood flow. These findings support the integration of Doppler ultrasound into the diagnostic work-up for infertility in similar resource-limited settings, as it identifies a potential, reversible contributor to poor endometrial receptivity.