The aim of this work was to investigate the effect of different vasodilators as pentoxifylline in women with unexplained infertility using IVF

A prospective randomized clinical study was carried out on 100 women, aged <18 to 43 years old, has good quality day five frozen embryos. The study was done after approval from the Ethical Committee Beni Suef University Hospitals, Beni Suef, Egypt. An informed written consent was obtained from the patients.

Randomization and blindness:

An online randomization program (http://www.randomizer.org ) was used to generate a random list and each patient's code was kept in an opaque sealed envelope. Patients were randomly allocated with 1:1 allocation ratio into two equal groups in a parallel manner: Group 1 (control):

received estradiol valerate 2 mg. in form of (Cycloprogynova® Bayer Shering Pharma) whitepills starting dose is one pill T.I.D may be increased to two pills T.I.D according to endometrial5 thickness in day 9 measured by vaginal ultrasound.

Group 2: received pentoxifylline 400 mg. Once daily in form of (Trental ® Sanofi co.) daily in addition to the above treatment protocol from the first day of the cycle until the day of starting progesterone.

All patients were subjected to complete history taking, general examination, laboratory investigations [Anti-müllerian hormone (AMH), follicle-stimulating hormone (FSH), luteinizing hormone (LH), estradiol (E₂), prolactin (PRL) and thyroid-stimulating hormone (TSH)] and radiological investigations [Ultrasonography]. The endometrial thickness was estimated by transvaginal ultrasonography.

Inclusion Criteria:

• as good quality day five frozen embryos.

Exclusion Criteria:

• history of endocrine diseases,
• history of any previous surgery that couldm compromise the integrity of endometrium,
• cardiovascular, renal and liver diseases,