Background: Nitric oxide plays a major role in increasing uterine blood flow during
the luteal phase and early pregnancy. This study was done to compare uterine artery
and sub-endometrial blood flow indices during the luteal phase between patients
with unexplained recurrent abortion and fertile women and also to evaluate the effects
of nitric oxide donors on blood flow indices in the abortion group.
Methods: The study included a control group of 30 primiparae who had normal vaginal
delivery and no history of abortion and an abortion group of 30 nulliparous
women with history of two or more unexplained recurrent abortions. Transvaginal
three-dimensional pulsed color Doppler ultrasound was done on days 21-23 of the
cycle to measure uterine artery resistance and pulsation indices and the subendometrial
vascular, flow and vascular-flow indices. Isosorbide mononitrate 20 mg tablet
was administered vaginally in the abortion group and blood flow indices were measured
again after two hours. The Student t-test and the paired t-test were used for
analysis of results and a p-value of ≤0.05 was considered significant.
Results: Patients with unexplained recurrent abortion had significantly higher uterine
artery resistance and pulsation indices and lower sub-endometrial vascular, flow
and vascular-flow index (p