Effects of Oral Sildenafil versus Nifedipine on the Uterine Artery Blood Flow Indices and Endometrial Thickness in Women with Unexplained Recurrent Pregnancy Loss

Abstract

Introduction and aim: Unexplained recurrent pregnancy loss (RPL) is a challenging condition faced during daily obstetric practice. Increased uterine blood flow and endometrial thickness were suggested to ameliorate the condition and increased uterine receptivity. The current study was designed to compare oral nifedipine and sildenafil regarding their effectiveness and safety profile in improvement of uterine artery blood flow and endometrial thickness in cases with unexplained RPL.    

Methodology: This study included 100 women with a history of unexplained RPL while they were not pregnant. They were divided into two equal groups. The first received oral Nifedipine (10 mg) twice daily, and the second received oral Sildenafil citrate (10 mg) three times a day from the 5^th to 25^th days of the menstrual cycle. All were submitted to a comprehensive clinical, laboratory and radiological assessment during the second phase of the menstrual cycle (day 15 to day 25). The transvaginal color doppler was used to estimate uterine artery pulsatility and resistive indices, and endometrial thickness before and after treatment.  

Results: Both groups were comparable regarding patient demographics, clinical and laboratory data. The uterine artery PI, RI and endometrial thickness before treatment were comparable between both groups. The paired comparisons in each group showed significant reduction of PI and RI and significant increase of endometrial thickness after treatment than before. Furthermore, the difference (before – after) of PI, RI and endometrial thickness were significantly higher in sildenafil than nifedipine groups (0.577±0.029, 0.417±0.090 and 0.3605±0.817 vs 0.545±0.029, 0.300±.001 and 3.180±0.775 for PI, RI and endometrial thickness differences, respectively). The side effects were in the form of headache, palpitation and flushing. They were reported in 18.0%, 10.0% and 10.0%, respectively in the nifedipine group, compared to 24.0%, 16.0% and 16.0% respectively in sildenafil group, with no significant differences between groups.

Conclusion: Both oral nifedipine and Sildenafil demonstrated a good safety profile, with good effectiveness in improving uterine artery doppler indices and subsequently improved uterine blood flow and increased thickness in women with unexplained RPL. However, Sildenafil is associated with better results than nifedipine with nearly similar safety profiles.