Sildenafil citrate decreased natural killer cell activity and enhanced chance of successful pregnancy in women with a history of recurrent miscarriage

ObjectiveTo evaluate the effect of sildenafil on peripheral natural killer (NK) cell activity in women with a history of recurrent miscarriage (RM).DesignObservational study.SettingUniversity teaching hospital.Patient(s)Thirty-eight nonpregnant women with a history of RM and 37 healthy women with previous successful pregnancy outcomes.Intervention(s)Patients self-administered sildenafil suppositories (25 mg intravaginally, four times a day) for 36 days.Main Outcome Measure(s)Peripheral blood NK-cell activity before and after vaginal sildenafil therapy in the RM women was measured using flow cytometry. In addition, the influence of 10 μg and 400 ng sildenafil on NK-cell activity after in vitro culture were determined. Uterine artery blood flow and endometrial thickness were recorded using Doppler ultrasound with an intravaginal probe.Result(s)The NK-cell activity was significantly decreased after vaginal sildenafil therapy. Endometrial thickness was significantly increased after such therapy.Conclusion(s)Vaginal sildenafil might be an interesting therapeutic option before conception in women with histories of reproductive failure.