Nitric oxide donors and implantation ROWAA A. MOSTAFA MD, FRCOG Implantation is a progressive process in which the embryo has to appose and attach itself to the maternal endometrium, and invade it. This process involves 2 sides: Endometrium Embryo Since the introduction of IVF ,there has been substantial improvement of all IVF steps. However, the endpoint, which is to improve implantation and pregnancy rates after transferring adequate number of embryos remains below expectations. The main reason for this disappointing result is the quality of the endometrial factor that is affected during COH . The fundamental question is : could implantation be improved in ART, therefore increasing the pregnancy rates in IVF/ ICSI cycles? Adjuvant medical therapies to improve implantation Several medical therapies were tried as adjuvants with progesterone to increase endometrial receptivity and improve implantation after ET. Aspirin. Ascorbic acid . Vitamin E. Corticosteroids. Heparin. Luteal E2 supplementation. Nitric oxide donors. Nitric oxide donors NO donors are compounds capable of releasing free NO in vivo. Several observations were behind the trials of using nitric oxide donors in ART in attempt to improve endometrial receptivity and implantation. These observations include No acts as a relaxant of blood vessels and smooth muscles of uterus. No inhibits platelets aggregation. NOS reaches peak levels in the endometrium during implantation window in natural cycle. Adequate uterine perfusion is an important factor in uterine receptivity. Various studies showed that high resistance to uterine blood flow at HCG time or at ET is correlated with poor outcome. Using Doppler ultrasonography, Goswamy and Steptoe, 1988 reported a high incidence of poor uterine perfusion in women with repeated failed IVF trials. They postulated that sub-optimal uterine blood flow could possibly be an independent factor of infertility. Types of NO donors: Organic: * Isosorbide mononitrate (ISMN). * Isosorbide dinitrate (ISDN). * Isosorbide trinitrate (ISTN). * Nitroglycerine. Non organic: * Nicorandial. * Molsidomine. A study was carried to assess the effect of nitric oxide donor on uterine blood flow , endometrial receptivity and implantation in IVF/ICSI . A better understanding of implantation is essential for further improvement of success rates in assisted conception treatment cycles Subjects and Methods The present study was conducted in Fertility IVF center in the period from September 2006 to May 2008. Forty women whom ICSI was indicated for male factor ( oligoasthenosprmia) were selected for this study. Their ages ranged from 25 to 35 year. . There were no other indications for ICSI in all participating women. Cases of PCOD were not included. The subjects received the long protocol of controlled ovarian hyper-stimulation using GnRH analogue decapeptyl 0.1 mg; Ferring and HMG , 75 IU FSH and LH; Menogon ,Ferring 2-3 amp /day. HCG ,pregnyl; Organon 10 000 IU was given by IMI when ≥ 3 follicles with a mean diameter of 18 mm or more were seen. Oocytes retrieval was done 36 hours later followed by ICSI. Each woman had ET of 2 or 3 good quality embryos on day 3 after oocytes retrieval. Cases with only one embryo available for transfer and /or no grade A embryos, were not included. Luteal phase support was undertaken with progesterone vaginal pessaries ( Cyclogest 400mg daily) starting on the day of oocytes retrieval and for 2 weeks after embryo transfer. Measurement of B-HCG was done after 2 weeks and if it is positive, transvaginal ultrasound scan is done 2 weeks later to assess the pregnancy. The subjects were divided randomly into 2 groups after embryo transfer. Group I: 20 women received nitric oxide donors in the form of nitroglycerin skin patch(Nitroderm 5mg/24 hours) Novartis pharma S.A.E; Basles Switzerland. The patch releases transdermal propanetriol trinitrate. The patches were used for 2 weeks. Group II: the other 20 women did not receive this treatment. Nitroderm TTs is a flat multilayer system designed to deliver nitroglycerin continuously through a release a release membrane following application to the skin. The active substance penetrates the skin and thus becomes directly bioavailable to the systemic circulation . Three Nitroderm skin patches are available: TTS 5, TTS 10 and TTS 15. The figures denote the nominal amount of nitroglycerin in mg delivered by the system in 24 hours. The rate of release is 20-25 ug/cm2. hr. TTS 5 was used in the current study. Uterine artery doppler blood flow assessment was done for all women on the day of HCG administration and one week later. The pulsatility index (PI) was used for this purpose. PI = peak systolic- end diastolic mean velocity for the entire cardiac cycle Transvainal probe 5 MHz of Color doppler ultrasonography (Digital GAIA , Sonace 8800, Medison; S.Korea ) machine was used. All scans were done by experienced operators and almost in the same time of the day to avoid diurnal variation in the uterine blood flow. Transvaginal pelvic scanning was first performed and the morphology of the uterus and ovaries was explored. Color flow mapping and pulsed Doppler measurements were performed to the uterine artery on both sides. Blood flow velocity waveforms were obtained and quantitated by the calculation of pulsatility index (PI). Results Table(1) patients characteristics Group I Group I I p Age(mean±SD)ys 29.8 ±3.0 30.6 ±2.7 BMI(mean±SD) 27.7 ± 3.4 26.4 ±3.5 >0.05 N.S Years of infertility ((mean ±SD) 7.4 ± 2.9 6.1 ± 3.8 >0.05 N.S >0.05 Signif. N.S Table (2) characteristics of treatment cycles Group I Group II (mean) (mean) P HMG ampoules 34.5±3.2 37.8 ±4.1 >0.05 HMG days 11.4±2.3 12.5±3.8 >0.05 Retrieved oocytes 7.4 ±2.2 8.7±3.1 >0.05 Fertilized oocytes 5.9±1.3 6.1±1.0 > 0.05 Fertilization rate 79.7±5.3% 73.1±4.8% >0.05 Transferred embryos 2.1± 0.5 2.5 ± 0.2 >0.05 Signif. N.S N.S N.S N.S N.S N.S Table (3) outcome of the trial Group I Mean PI on day HCG Mean PI after 1 wk No of pregnancies singleton twin Pregnancy rate Implantation rate 2.76 ±0.77 2.01 ± 0.52 8 6 2 40% 21.7 % Group II 2.83±0.56 2.70±0.42 6 6 0 30% 13.1% P >0.05 <0.05 >0.05 <0.05 Signif. NS S NS S Table (4) PI and pregnancy No of cases No of pregnancies PI on HCG day low(1-1.99) medium (2-2.99) high (>3.0) 4 29 7 3 11 0 PI after 1 week low medium high 7 30 3 5 9 0 Conclusions Implantation process constitutes the limiting factor to increase pregnancy rates in ART. Optimal uterine perfusion is an important factor for uterine receptivity and consequently successful implantation. Nitric oxide donors may hove a role in optimizing uterine blood flow and perfusion. Their use may improve implantation which can increase pregnancy rate in ART treatment cycles.