Changes in Blood-flow Impedance of the Human Corpus Luteum Throughout the Luteal Phase and During Early Pregnancy

Objective: To examine changes in blood flow in the corpus luteum throughout the luteal phase and during early pregnancy.

Design: Longitudinal and cross-sectional prospective studies.

Setting: University 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 Measures: Resistance 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.