Assessment of uterine blood flow in women with unexplained recurrent pregnancy loss with the effects of nitric oxide donors

Abstract EN

Objectives: The aim of the current work is to assess the uterine artery pulsatility index and resistance index in women with unexplained recurrent pregnancy loss, in comparison to women with no history of abortion.

In addition, it also aimed to evaluate the effect of lsosorbide mononitrate, a nitric oxide donor administered vaginally, on uterine blood flow patterns.

Study design: A cross-section, controlled observational study.

Setting: Al-Azhar University Hospitals, (Al-Hussein and Bab El- Shaaria).

Subjects and Methods: Two groups of women each 50 cases were studied.

The control group included women with no such prior history of recurrent pregnancy loss and delivered at least one living child.

The study group included non-pregnant women with a history of three or more consecutive unexplained first and second trimester miscarriages before 20 weeks.

Vaginal color Doppler ultrasound was done in the mid- luteal phase of the menstrual cycle to measure uterine artery resistance and pulsatility indices, then 20 mg isosorbid mononitrate tablet was applied vaginally in the study group and the doppler indices were measured again after two hours.

Outcome Measures: Comparison between uterine artery resistance and pulsatiliy indices in both groups and the effects of isosorbid mononitrate on these indices in the study group.

Results: Women with recurrent pregnancy loss had significant higher uterine artery resistance and pulsatility indices.

Isosorbid mononitrate applied vaginally causes significant decrease in these indices.

Conclusions: The theoretical implication of uterine vascular impairment in the pathogenesis of 'unexplained' RPL seems to be quite logical; an adequate uterine circulation is essential for the normal early pregnancy development and maintenance and therefore, any impairment could be harmful.

The results of this study support this interesting theory.

Nitric oxide (NO) recently becomes of clinical interest because of its relaxant effect on the smooth muscles.

In addition to endothelial cells also myometrial cells contain the enzyme implicated in the NO production.

It must be noted that the number of cases analyzed by this study was small, and that similar previous studies are few.

New studies are necessary, ideally multicenter studies, to better elucidate the association between spontaneous abortion and inadequate uterine perfusion, identified through a doppler evaluation of the uterine arteries.

Impaired uterine perfusion could play a central role in the pathogenesis of RPL.

Isosorbide mononitrite, nitric oxide donor could be an effective treatment for correction of uterine vasculature in patient with RPL.