Endometrial fluid visualized through ultrasonography during ovarian stimulation in IVF cycles impairs the outcome in tubal factor, but not PCOS, patients

BACKGROUND: The aim of the present study was to examine the impact of the presence of endometrial fluid (seen through ultrasound) on the outcome of IVF cycles and its association with the aetiology of infertility, in tubal and polycystic ovary syndrome (PCOS) cases specifically. METHODS: We retrospectively evaluated the charts of all PCOS and tubal factor infertility patients that underwent IVF between June 1, 2001 and May 31, 2002. Twenty-four PCOS and 14 tubal factor infertility patients in whom endometrial fluid was detected were compared with 94 PCOS and 160 tubal factor patients whose stimulation cycles did not show any fluid collection. The main outcome measures were implantation and pregnancy rates. RESULTS: Implantation rates were lower in the tubal factor patients in the presence of endometrial fluid (6.12% and 21.4%, respectively) in comparison with all other tubal factor infertile patients in whom no fluid accumulation inside the cavity was detected. In PCOS cycles there was no significance in patients with presence of endometrial fluid in comparison with the all other PCOS cycles without any fluid accumulation. CONCLUSIONS: When fluid collection inside the endometrial cavity is first seen during ovarian stimulation of PCOS patients undergoing IVF, embryo transfer can be performed safely if the fluid has disappeared and not returned by the day of embryo transfer. However, in tubal factor cycles one should think of either cancellation of the cycle or cryopreservation of all embryos.     

Hydrosalpinx affects the implantation of previously cryopreserved embryos

The presence of hydrosalpinx has been reported to negativelyaffect the pregnancy and implantation rate after in-vitro fertilization(IVF) with embryo transfer. Hydro-salpinges are able to enlargeduring ovarian stimulation with a possible increased passageof tubal fluid into the endometrial cavity. We report the effectof hydrosalpinges during the transfer of previously cryopreserved/thawedembryos during a natural cycle. In all, 14 transfers in 10 patientswith a sonographically-documented hydrosalpinx during the studiedcycle (group I) were compared to 98 cycles in 74 patients withtubal disease but no such sonographic finding (group II). Bothpregnancy and implantation rates were significantly lower ingroup I (7.14 versus 24.49% and 5.0 versus 10.8% respectively).The presence of hydrosalpinx negatively affects pregnancy andimplantation rates during natural cycles.     

Fluid accumulation within the uterine cavity reduces pregnancy rates in women undergoing IVF

BACKGROUND: The occurrence of fluid accumulation within the uterine cavity was examined in women undergoing IVF to investigate its correlation with tubal disease and impact on the pregnancy outcome. METHODS: A registry of ultrasound procedures spanning 5 years was retrospectively studied. RESULTS: Thirty five out of 746 (4.7%) IVF cycles were identified as having uterine fluid accumulation, and 15 (2.0%) persisted until the day of embryo transfer. Two of the 20 cycles of women with transient fluid accumulation were pregnant, and none of those with fluid retention on the day of embryo transfer conceived. The pregnancy rate was only 5.7% (2/35) in women with uterine fluid accumulation detected during IVF cycles. In contrast, the pregnancy rate was 27.1% (193/711) among women in whose cycles no fluid accumulation was detected (P = 0.0048). Uterine fluid accumulation during IVF cycles was found in 8% (18/225) of women documented with tubal factor compared with 3.3% (17/521) with non-tubal factor (P = 0.005). CONCLUSIONS: Fluid accumulation within the uterine cavity during the IVF transfer treatment could be observed in patients with both tubal and non-tubal factors; however, it mainly occurred in women with tubal infertility. Although it is not a common complication of IVF cycles, excessive uterine fluid is detrimental to embryo implantation.     

Recurrence of hydrosalpinges after transvaginal aspiration of tubal fluid in an IVF cycle with development of a serometra

The presence of hydrosalpinges has been shown to be deleterious in infertility treatment. Pregnancy rates after in-vitro fertilization (IVF) with embryo transfer decline considerably. This study concerns a patient who developed bilateral hydrosalpinges during controlled ovarian stimulation in preparation for IVF treatment. Transvaginal aspiration of the tubal fluid was unsuccessful as the tubes refilled within 2 days. Additionally, on the day of embryo transfer a serometra developed which could not be seen on the day of oocyte retrieval. The uterine cavity was evacuated via an embryo transfer catheter and three embryos were transferred. The serometra reappeared 3 days after embryo transfer. A pregnancy could not be achieved. The accumulation of fluid in the uterine cavity during an IVF/embryo transfer cycle is a rare complication of hydrosalpinges. However, the retrograde flow of tubal fluid may disturb intrauterine embryo development. This study suggests that the aspiration of hydrosalpinges and intrauterine fluid accumulation during an IVF cycle is not beneficial, as the underlying pathology is not cured. Cancellation of the treatment cycle or cryopreservation of oocytes in the pronucleate stage and transfer of the cryopreserved oocytes after surgical correction of the tubes may be better options.      

Is hydrosalpinx fluid cytotoxic?

Accumulation of oviductal fluid in the ampullar lumen as a result of occlusion of the infundibulum is referred to as hydrosalpinx. A low pregnancy rate (10%) after in-vitro fertilization (IVF) in hydrosalpinx patients and a relatively high incidence (50%) of abortions during the first trimester suggested that leakage of this fluid into the uterine cavity may exert a cytotoxic effect on the developing embryo. To examine this possibility, we analysed the composition of the hydrosalpinx fluid and tested its effect on human granulosa cells and embryos. Hydrosalpinx fluids and granulosa cells were collected from IVF patients at ovum pick-up. IVF eggs containing three pronuclei (3PN) were employed for this study. Analysis of hydrosalpinx fluids revealed electrolyte concentrations similar to those in serum with lower amounts of total protein and albumin. No blood cells were detected and bacterial cultures were negative. Granulosa cells incubated in hydrosalpinx fluid-containing medium (diluted 1:1) were not morphologically different and showed a steroidogenic capacity that was higher than that of cells incubated in its absence. Fertilized 3PN eggs incubated in IVF culture medium successfully developed into 6- to 8- and 8- to 16-cell embryos within 48 and 72 h, respectively. This rate of embryonal development was not impaired by hydrosalpinx fluid (at either 50 or 100% concentration). In the absence of a demonstrable detrimental effect we suggest that the low implantation rate in hydrosalpinx IVF patients may not be due to an embryotoxic effect. We further suggest that constant passage of fluid into the uterine cavity in these patients could possibly introduce some mechanical interference that may result in implantation failure.      

No evidence of increased uterine vascular impedance with patient ageing following IVF

A study was conducted to determine if uterine vascular impedance increases with advancing age in women undergoing ovarian stimulation for IVF. A group of 162 women who had undergone conventional IVF and embryo transfer was subdivided into three subgroups by age: 30-34 years (n = 49), 35-39 years (n = 79) and 40-44 years (n = 34). The pulsatility index (PI) and resistance index (RI) of the right and left uterine arteries were measured at baseline, on the day of oocyte retrieval, and at the mid-luteal phase. There were no differences in the average PI or RI by age at any phase of the cycle. In all age groups, the luteal phase values of PI and RI were lower than those observed earlier in the cycle. Endometrial thickness was not associated with age. There was no significant correlation between PI, RI and serum oestradiol and progesterone concentrations at any phase of the cycle. Ovarian response, as measured by average number of oocytes retrieved, decreased significantly with age. Thus, reduced pregnancy rates in older women undergoing ovarian stimulation are more likely to occur because of oocyte quality and quantity rather than uterine senescence. If future studies determine that the use of ovarian stimulation does decrease implantation rates more in older versus younger women, a mechanism other than increased uterine vascular impedance must be sought.     

Nitric oxide donors for patients undergoing IVF. A prospective,double-blind,randomized, placebo-controlled trial

BACKGROUND: Nitric oxide (NO) is involved in local control of the uterine cycle and in preparation of the uterus for pregnancy. NO donors, acting as vasodilating agents, may therefore have possible therapeutic uses, for example they may be of benefit to patients with a history of implantation failure. In a prospective, comparative, randomized, placebo-controlled study, we assessed the efficacy of nitroglycerin (NTG) administered to 138 IVF patients with a history of implantation failure. METHODS: Controlled ovarian stimulation was performed with long agonist protocol combined with recombinant FSH. Embryos were transferred on day 2 or 3 after oocyte retrieval. Eligible patients were those who had at least two 'good quality' embryos. The NTG patch was administered the day before embryo transfer and continued until either the results of the pregnancy test were known or until menstruation occurred. RESULTS: Ovarian response, implantation rate and pregnancy rate were comparable between both groups. No difference was observed in uterine Doppler findings, particularly the mean pulsatility index. CONCLUSIONS: NTG treatment the day before embryo transfer was no more effective than placebo in improving the implantation or pregnancy rates in a population of IVF patients with a previous history of implantation failures.     

Effect of uterine leiomyomata on the results of in-vitro fertilization treatment

The effect of uterine leiomyoma on infertility is subject tocontroversy. Two main mechanisms associating leiomyomata andinfertility have been suggested: the obstruction of gamete transportand impaired implantation. In-vitro fertilization (IVF) is aunique setting for examining the effect of leiomyomata on theimplantation rate. This study was designed to determine theimpact of uterine leiomyomata on the results of IVF. In a retrospectiveanalysis of IVF cycles, 46 women with documented uterine leiomyomawere compared with a control group with mechanical infertility.The implantation rate and pregnancy outcome in relation to theleiomyoma were observed. Implantation (22.1%/transfer, 6.8%/embryo)and abortion rates (36%)in the study group were similar to theresults in the control group with pure mechanical factor. Ananalysis of IVF results according to the hysteroscopic pretreatmentfindings revealed that impaired implantation is associated withleiomyoma only where uterine intracavitary abnormalities co-exist.We conclude that implantation rate and pregnancy outcome areimpaired in women with uterine leiomyomata only when they causedeformation of the uterine cavity. In patients with leiomyomataassociated with an abnormal uterine cavity, surgical treatmentshould be considered prior to IVF because of the reduced implantationrate.     

The influence of the depth of embryo replacement into the uterine cavity on implantation rates after IVF: a controlled, ultrasound-guided study

BACKGROUND: Traditionally, embryo transfer after IVF has been performed blindly and placing the embryos approximately 1 cm below the fundal endometrial surface. However, it has been suggested that transferring embryos rather lower in the uterine cavity or high in the uterus may improve implantation rates. Nevertheless, there has not yet been a controlled trial to prove this theory. This prospective randomized study investigates the influence of the depth of embryo replacement on the implantation rate after embryo transfer carried out under transabdominal ultrasound guidance. METHODS: A total of 180 consecutive patients undergoing ultrasound-guided embryo transfer were randomized to three study groups according to the distance between the tip of the catheter and the uterine fundus at the moment of the embryo deposition in the lumen of the endometrial cavity: group 1: 10 +/- 1.5 mm; group 2: 15 +/- 1.5 mm; group 3: 20 +/- 1.5 mm. RESULTS: There was equal distribution between all three study groups regarding the main demographic and baseline characteristics of the patients, ovarian response, oocyte retrieval and IVF outcome, as well as the characteristics of embryo transfer and luteal phase support. The position of the catheter tip in relation to the fundal endometrial surface in groups 1 (10.2 +/- 0.9 mm), 2 (14.6 +/- 0.7 mm) and 3 (19.3 +/- 0.8 mm) was significantly different. Implantation rate was significantly higher (P < 0.05) in groups 2 (31.3%) and 3 (33.3%) compared with group 1 (20.6%). CONCLUSIONS: The depth of the embryo replacement into the uterine cavity may influence implantation rates, and thus it should be considered as an additional procedure among factors recently proposed as associated with successful embryo transfer after IVF.     

Quantitative assessment of subendometrial blood flow by three-dimensional-ultrasound is an important predictive factor of implantation in an in-vitro fertilization programme

This study was designed to investigate the role of three-dimensional (3D) power Doppler sonography of the (sub-) endometrial area on the first day of ovarian stimulation in predicting the outcome of an in-vitro fertilization (IVF) programme. Among the 75 cycles analysed, the overall pregnancy rate was 20% (15/75) per cycle and 23.8% (15/63) per embryo transfer. Intra-observer variability of the colour histogram was checked in 14 patients with the results demonstrating a high level of agreement. Neither endometrial measurements nor uterine blood flow were correlated with the pregnancy rate. In contrast, all 3D indices were significantly lower in conception compared with non-conception cycles (P < 0.05). Logistic regression analysis found the subendometrial flow index to be the strongest predictive factor of IVF success among the tested sonographic parameters (P = 0.04). In conclusion, quantitative assessment of spiral artery blood flow may be of predictive value for implantation in IVF cycles even before ovarian stimulation therapy is started.     

Comparison of agonistic flare-up-protocol and antagonistic multiple dose protocol in ovarian stimulation of poor responders: results of a prospective randomized trial

The management of poor responders in IVF has always been a big problem. The ideal approach has yet to be formulated. In this study we aim to compare two alternative stimulation protocols. A total of 48 poor responder patients described from previous cycles were included and grouped into two: group I consisted of 24 patients in 24 cycles in which leuprolide acetate (40 microg s.c. per day) was initiated on cycle day 2 followed by exogenous gonadotrophins on cycle day 3; group II consisted of 24 patients in 24 cycles in which ovarian stimulation included gonadotrophin-releasing hormone (GnRH) antagonist (cetrorelix, 0.25 mg daily during late follicular phase) administration. While only the oestradiol concentrations on the day of HCG were lower in group II compared with group I, the clinical pregnancy and implantation rates among groups did not show any significance. The impact of these two regimens in ovarian stimulation of poor responders seem to be same and to establish these results further randomized studies with larger sample sizes are required.     

The mechanism of hydrosalpinx in embryo implantation.

BACKGROUND: Hydrosalpinx adversely affects embryo implantation and contributes to poor implantation rates post embryo transfer. Embryo transport depends on concomitant intrauterine fluid motion induced by uterine wall motility, the result of spontaneous myometrial contractions towards the fundus. METHODS AND RESULTS: The uterine dynamics of five patients with hydrosalpinx were recorded and analysed by image-processing techniques: the frequency was higher while the amplitudes and passive widths were lower compared with healthy volunteers. The existing peristaltic activity should have induced intrauterine fluid flow; however, the recordings failed to show the expected transport of fluid bolus. This observation was supported by mathematical simulations based on the hypothesis that fluid accumulation in the Fallopian tube of a patient with hydrosalpinx increases tubal pressure and thereby induces a pressure gradient between the fundus and the cervix. This pressure gradient acts adversely to the cervix-to-fundus intrauterine peristalsis and generates reflux currents that may thrust embryos away from the implantation site. CONCLUSIONS: The reflux phenomenon could explain the reduced implantation rate associated with hydrosalpinx. Resolution of the issue of whether the removal of a Fallopian tube with hydrosalpinx should be undertaken for improving IVF pregnancy rates should be accompanied by prospective randomized clinical trials.     

Suppression of LH during ovarian stimulation: analysing threshold values and effects on ovarian response and the outcome of assisted reproduction in down-regulated women stimulated with recombinant FSH

BACKGROUND: It has been recently suggested that gonadotrophin-releasing hormone agonist down-regulation in some normogonadotrophic women may result in profound suppression of LH concentrations, impairing adequate oestradiol synthesis and IVF and pregnancy outcome. The aims of this study, where receiver-operating characteristic (ROC) analysis was used, were: (i) to assess the usefulness of serum LH measurement on stimulation day 7 (S7) as a predictor of ovarian response, IVF outcome, implantation, and the outcome of pregnancy in patients treated with recombinant FSH under pituitary suppression; and (ii) to define the best threshold value, if any, to discriminate between women with 'low' or 'normal' LH concentrations. METHODS: A total of 144 infertile women undergoing IVF/intracytoplasmic sperm injection (ICSI) treatment were included. Seventy-two consecutive patients having a positive pregnancy test (including 58 ongoing pregnancies and 14 early pregnancy losses) were initially selected. As a control non-pregnant group, the next non-conception IVF/ICSI cycle after each conceptual cycle in our assisted reproduction programme was used. RESULTS: The median and range of LH values in non-conception cycles, conception cycles, ongoing pregnancies, and early pregnancy losses, clearly overlapped. ROC analysis showed that serum LH concentration on S7 was unable to discriminate between conception and non-conception cycles (AUC(ROC) = 0.52; 95% CI: 0.44 to 0.61) or ongoing pregnancy versus early pregnancy loss groups (AUC(ROC) = 0.59; 95% CI: 0.46 to 0.70). To assess further the potential impact of suppressed concentrations of circulating LH during ovarian stimulation on the outcome of IVF/ICSI treatment, the three threshold values of mid-follicular serum LH proposed in the literature (<1, < or =0.7, <0.5 IU/l) to discriminate between women with 'low' or 'normal' LH were applied to our study population. No significant differences were found with respect to ovarian response, IVF/ICSI outcome, implantation, and the outcome of pregnancy between 'low' and 'normal' S7 LH women as defined by those threshold values. CONCLUSIONS: Our results do not support the need for additional exogenous LH supplementation in down-regulated women receiving a recombinant FSH-only preparation.     

Controversies in the modern management of hydrosalpinx

The management of hydrosalpinx is a difficult clinical problem. Surgical treatment includes fimbrioplasty for patients with fimbrial obstruction and salpingostomy to fashion a stoma in the distal Fallopian tube in patients with a damaged fimbrial end. Surgery is only suitable for a small thin-walled hydrosalpinx with healthy mucosa. These operations can be performed via laparoscopy or open microsurgery. The proper selection of patients for surgical treatment and of the type of surgical technique are essential to achieve good results. The results of open microsurgery and laparoscopic surgery are summarized. In general, the prognosis of surgery is poor; however, in well selected cases, good results can be achieved by an experienced surgeon. In-vitro fertilization (IVF) is the main line of treatment for infertility caused by hydrosalpinx. In 1991, our group was the first to report on fluid accumulation in the uterine cavity before embryo transfer as a possible hindrance for implantation. Later, several publications reported an association between patients with hydrosalpinx and a reduced pregnancy rate when treated by IVF. The cause of a low pregnancy rate could be due to mechanical, chemical or toxic effects of the tubal fluid on the endometrium preventing implantation. All these mechanisms are reviewed in detail. The literature is controversial concerning the effect of transvaginal aspiration of hydrosalpinx on the outcome of IVF. Several reports suggest that surgical correction of the hydrosalpinx may improve the outcome of IVF. Further studies are required to verify this assumption and to find out the most suitable surgical procedure and if there is a subgroup of patients who could benefit most from salpingectomy.     

Addition of GnRH antagonist in cycles of poor responders undergoing IVF

Concern about the use of gonadotrophin-releasing hormone (GnRH) agonists in ovarian stimulation of poor responder IVF patients has arisen from the claim that GnRH agonists might have a direct deleterious effect through their receptors on the ovary. In this study, we compared two ovarian stimulation protocols in which no GnRH agonists were used. In all, 40 patients with a poor response in previous treatment cycles were included. They were divided into two groups: group I (n = 20) received ovarian stimulation for 20 cycles, without the addition of either GnRH agonist or antagonist; while group II (n = 20) patients received ovarian stimulation for 20 cycles, including the administration of a GnRH antagonist (Cetrorelix, 0.25 mg daily) during the late follicular phase. There was no statistically significant difference between the groups for mean age, duration of infertility, baseline FSH concentration, cancellation rate, number of ampoules of gonadotrophin used, number of mature oocytes retrieved, oestradiol concentrations on the day of injection of human chorionic gonadotrophin (HCG), fertilization rate and number of embryos transferred. The clinical pregnancy and implantation rates in group II appeared higher than in group I, but were not significantly different (20 and 13.33% compared with 6.25 and 3.44% respectively). The addition of GnRH antagonists to ovarian stimulation protocols might be a new hope for poor responder IVF patients, but this report is preliminary and further controlled randomized prospective studies with larger sample sizes are required.     

Analysis of intra-uterine cytokine concentration and matrix-metalloproteinase activity in women with recurrent failed embryo transfer

BACKGROUND: In all IVF programmes, some patients fail to achieve an ongoing pregnancy, even after numerous embryo transfer procedures. An unfavourable environment within the uterus might be a contributory factor to such recurrent implantation failure. This question was addressed by measuring cytokine concentrations and matrix metalloproteinase activities in fluid derived from uterine irrigation of such patients. METHODS AND RESULTS: The uterine cavities of 22 patients who had previously undergone embryo transfer of at least 10 embryos without ongoing pregnancy were irrigated during the luteal phase. The resultant fluid was assayed for the concentration of interleukin (IL)-1beta, tumour necrosis factor (TNF)-alpha, interferon (IFN)-gamma, leukaemia inhibitory factor (LIF), IL-10 and matrix metalloproteinase (MMP) -2 and -9 activity. The results were compared with those of a control population of women known to be previously fertile (n = 16) and also with women with recurrent spontaneous abortion (n = 13). In the recurrent implantation failure group, the MMP score and IL-1beta concentration were significantly higher than those in the control group, whereas concentrations of IFN-gamma and IL-10 were significantly lower. CONCLUSIONS: In IVF patients with recurrent implantation failure, an altered pattern of intra-uterine cytokine concentration and MMP activity was observed.     

Concentration of leukaemia inhibitory factor (LIF) in uterine flushing fluid is highly predictive of embryo implantation.

BACKGROUND: There is strong evidence that locally secreted cytokines control the implantation process and can cause implantation failure. Uterine flushing fluids were analysed to determine their concentrations of leukaemia inhibitory factor (LIF) and tumour necrosis factor (TNF). METHODS AND RESULTS: We began by flushing the uterine cavities of 33 infertile patients on day 26 of two consecutive cycles. The concentrations of LIF (by enzyme-linked immunosorbent assay) and TNF (by bioassay) were significantly correlated during these cycles (r = 0.762, P = 0.0001 and r = 0.822, P = 0.001 respectively) and hence reliable. Then, after a reference flushing of 30 infertile patients, we followed the outcome of their first consecutive cycle of ovarian stimulation, which preceded either IVF or intrauterine insemination. A total of 10 patients became pregnant. The median concentration of LIF was 0 pg/ml (range: 0-177) and of TNF was 0 U/ml (range: 0-6.17) among those who became pregnant, and 203 pg/ml (range: 0-1620) and 2.14 U/ml (range: 0-16) respectively among those who did not. The LIF concentration was significantly lower in the pregnant group (P = 0.0013). CONCLUSION: A low concentration of LIF in the uterine flushing fluid at day 26 was predictive of subsequent implantation. Use of this procedure should increase the number of IVF attempts yielding successful pregnancies and also lead to corrective therapies.     

GnRH agonist versus GnRH antagonist in oocyte donation cycles: a prospective randomized study

BACKGROUND: The specific role of LH in folliculogenesis and oocyte maturation is unclear. GnRH antagonists, when administered in the late follicular phase, induce a sharp decrease in serum LH which may be detrimental for IVF outcome. This study was performed to evaluate whether the replacement of GnRH agonist (triptorelin) by a GnRH antagonist (ganirelix; NV Organon) in oocyte donation cycles has any impact on pregnancy and implantation rates. METHODS: A total of 148 donor IVF cycles was randomly assigned to use either a GnRH antagonist daily administered from the 8th day of stimulation (group I) or a GnRH agonist long protocol (group II) for the ovarian stimulation of their donors. The primary endpoints were the pregnancy and the implantation rates. RESULTS: The clinical pregnancy rate per transfer (39.72%, 29/73 versus 41.33%, 31/75) based on transvaginal scan findings at 7 weeks of gestation, the implantation rate (23.9 versus 25.4%) and the first trimester abortion rate (10.34 versus 12.90%) were similar in the two groups. CONCLUSION: In oocyte donation cycles the replacement of GnRH agonist by a GnRH antagonist appears to have no impact on the pregnancy and implantation rates when its administration starts on day 8 of stimulation.     

IVF following impossible or failed surgical reversal of tubal sterilization

Microsurgical re-anastomosis or IVF offer ways of reversing previous tubal sterilization. This retrospective study analysed 56 attempts of IVF in 37 couples after impossible or failed surgical sterilization reversal. Efficacy of IVF in this group (TL) was compared with that of a tubal pathology control group (TP) at all stages of IVF (stimulation, fertilization and implantation). Depending on patient age, significantly fewer oocytes were produced after ovarian stimulation in the TL group than in the control (TP) group (P = 0.023 for all TL patients; P = 0.02 when patients aged >38 years were excluded). The total number of embryos available for transfer was significantly lower in the TL group (P = 0.0042), but this was age-related, since when women aged >38 years were excluded there was no significant difference between the two groups. The ongoing pregnancy rate was similar in both groups, the probability of ongoing pregnancy appearing to depend on patient age rather than on previous fertility.     

Chromosomal aneuploidy in embryos conceived with unstimulated cycle IVF

There is an ever increasing trend in reproductive medicine to reduce the intensity of ovarian stimulation for in vitro fertilization (IVF) and to restrict the number of embryos that are transferred into the uterine cavity. Recent findings suggest that the magnitude of ovarian stimulation affects the proportion of euploid embryos. As a result of the restriction in the number of embryos transferred, it becomes even more important to select the embryo with optimum implantational and developmental potential. Our aim was to asses the prevalence of numerical chromosomal abnormalities (aneuploidy) in unstimulated cycle IVF embryos. Thirty patients (mean age 31.4 years) underwent oocyte retrieval in a natural cycle without any form of ovarian stimulation, followed by intracytoplasmic sperm injection and Preimplantation genetic aneuploidy screening (PGS) for chromosomes X, Y, 13, 16, 18, 21 and 22. Out of 30 cycles, 21 oocytes were retrieved, 15 of which fertilized successfully. Eleven embryos developed sufficiently in order to undergo the PGS analysis, and four embryos proved to be aneuploid (36.4%; 95% CI: 10.9-69.2%). Six normal embryos were transferred in utero, resulting in three ongoing pregnancies. Two healthy girls were born and one patient miscarried. Numerical chromosomal abnormalities (aneuploidy) are present even in embryos of young women, and in the absence of ovarian stimulation.