Effect of Nitric Oxide Donors on Uterine and Subendometrial Blood Flow in Patients With Unexplained Infertility

Inclusion Criteria: 1. Age between 20-35 years.6 2. Normal husband's semen analysis (WHO 2010 Criteria): * Count ≥15 million * Motility ≥ 32% progressive motility * Morphology ≥ 4% normal morphology 3. Documented ovulation ( basal body temperature , mid-luteal serum progesterone ≥3 ng / ml and ultrasound monitoring of ovulation). 4. Patent Fallopian tube and excluding uterine anomalies either by hystero-salpingogram (HSG) and/or laparoscopy. 5. Normal hormonal profile (serum progesterone, E2, F.S.H, LH and T.S.H In the 2ND Day of menstrual cycle) Exclusion Criteria: 1. Male factor of infertility. 2. Patients with uterine pathology as fibroids. 3. Tubal factor of infertility diagnosed by hysterosalpingography (HSG) or laparoscopy. 4. Patients with any contraindications for NO such as chronic liver and renal disease, known cardiac disease and migraine. 5. Diagnosis of PCO based on Rotterdam criteria, two out of three of the following are required to make the diagnosis (Rotterdam, 2004): * Oligo- and/or anovulation. * Clinical and/or biochemical signs of hyperandrogenism. * Polycystic ovaries (by transvaginal ultrasound): the morphology of PCO has been defined as an ovary with 12 or more follicles measuring 2-9 mm in diameter and/or increased ovarian volume (\>10 cm3) (Balen et al, 2003). 6. Conditions that mimic PCOS; disorders that cause oligo/anovulation and/or hyperandrogenism, such as: * Thyroid disease. * Non classic congenital adrenal hyperplasia. * Hyperprolactinemia. * Androgen-secreting tumors. 7. Women who had any medical comorbidity (e.g. autoimmune disease or diabetes mellitus) and those who have been using medications to induce ovulation or medications known to affect the VEGF concentration (NSAIDs) were not included in the study.