Changes in blood-flow impedance of the human corpus luteum throughout the luteal phase and during early pregnancy

ObjectiveTo examine changes in blood flow in the corpus luteum throughout the luteal phase and during early pregnancy.DesignLongitudinal and cross-sectional prospective studies.SettingUniversity hospital and city general hospital.Patient(s)Sixty-one women with normal menstrual cycles and normal luteal function, 13 women with hCG-induced ovulatory cycle, 10 women with luteal phase defect, six women with luteinized unruptured follicle (LUF), and 17 pregnant women (4–10 weeks of gestation).Intervention(s)Blood-flow impedance in the corpus luteum was assessed by transvaginal color-pulsed Doppler ultrasound.Main Outcome MeasuresResistance index (RI) in the corpus luteum.Result(s)In the normal menstrual cycle, the RI of the preovulatory follicle was high and significantly decreased after ovulation. Luteal-RI further decreased during the early to midluteal phase but significantly increased during the late luteal phase. Those changes in luteal-RI were similar to those of the hCG-induced ovulatory cycle. Luteal-RI during the midluteal phase was significantly higher in the patients with luteal phase defect than in women with normal luteal function. Luteal-RI of the LUF patients remained high throughout the luteal phase. In pregnant women, luteal-RI remained at the midluteal phase level until 7 weeks of gestation and significantly increased thereafter.Conclusion(s)The change in luteal-RI was associated with corpus luteum development and corpus luteum regression. Luteal-RI was closely associated with luteal function.