Adjuvants in IVF-evidence for what works and what does not work.

The field of assisted reproductive technology is shaped and changed constantly by advances in science and cutting-edge innovations. In a quest to maximise outcomes, add-on interventions are often adopted and utilised prematurely while the principles of evidence-based medicine seem to be less strictly adhered to. In this review we will attempt to summarise the latest evidence about some of the adjuvants.

Hemangiopericytoma arising from the cartilage of the external auditory canal.

BACKGROUND: Hemangiopericytomas (HPCs) are soft tissue tumors with histological variability and unpredictable clinical and biological behavior. HPCs in the head and neck are uncommon, the growth pattern is nonspecific; thus, diagnosis is often made by exclusion. METHODS: A 43-year-old man complained of a short history of right ear pain associated with a growing mass in the right external auditory canal. Subsequent hearing loss in the right ear brought the patient to undergo a CT scan and an MRI. The relevant literature was also reviewed. RESULTS: The imaging revealed a neoplasm arising from the floor of the right external auditory canal. The neoplasm was removed with the diagnosis of HPC. CONCLUSION: The literature reports few cases of HPC of the external auditory canal. Their rarity in this area leads to difficulties in diagnosis. Morphology is not predictive of their behavior, so close follow-up is mandatory for their correct management.

Prospective study into the value of the automated Elecsys antimüllerian hormone assay for the assessment of the ovarian growing follicle pool.

OBJECTIVE: To evaluate a new fully automated assay measuring antimüllerian hormone (AMH; Roche Elecsys) against antral follicle count in women of reproductive age. DESIGN: Prospective cohort study. SETTING: Hospital infertility clinics and academic centers. PATIENT(S): Four hundred fifty-one women aged 18 to 44 years, with regular menstrual cycles. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): AMH and antral follicle count (AFC) determined at a single visit on day 2-4 of the menstrual cycle. RESULT(S): There was a statistically significant variance in AFC but not in AMH between centers. Both AFC and AMH varied by age (overall Spearman rho -0.50 for AFC and -0.47 for AMH), but there was also significant between-center variation in the relationship between AFC and age but not for AMH. There was a strong positive correlation between AMH and AFC (overall spearman rho 0.68), which varied from 0.49 to 0.87 between centers. An agreement table using AFC cutoffs of 7 and 15 showed classification agreement in 63.2%, 56.9% and 74.5% of women for low, medium, and high groups, respectively. CONCLUSION(S): The novel fully automated Elecsys AMH assay shows good correlations with age and AFC in women of reproductive age, providing a reproducible measure of the growing follicle pool.

British Fertility Society Policy and Practice Committee: adjuvants in IVF: evidence for good clinical practice.

Optimisation of the environment favourable for satisfactory ovarian response to stimulation and successful embryo implantation remains at the core of assisted conception programmes. The evidence base for the routine use of different adjuvants, alone or in combination, for women undergoing their first in vitro fertilisation (IVF) treatment cycle and for those with poor prognosis is inadequate. The aim of this document is to update the last review of the available literature carried out by the British Fertility Society Policy and Practice Committee (BFS P&P) published in 2009 and to provide fertility professionals with evidence-based guidance and recommendations regarding the use of immunotherapy, vasodilators, uterine relaxants, aspirin, heparin, growth hormone, dehydroepiandrosterone, oestrogen and metformin as adjuvants in IVF. Unfortunately despite the lapse of 5 years since the last publication, there is still a lack of robust evidence for most of the adjuvants searched and large well-designed randomised controlled trials are still needed. One possible exception is metformin, which seems to have a positive effect in women with polycystic ovary syndrome undergoing IVF. Patients who are given other adjuvants on an empirical basis should always be informed of the lack of evidence and the potential side effects.

Definition and epidemiology of unexplained infertility.

The diagnosis of unexplained infertility can be made only after excluding common causes of infertility using standard fertility investigations,which include semen analysis, assessment of ovulation, and tubal patency test. These tests have been selected as they have definitive correlation with pregnancy. It is estimated that a standard fertility evaluation will fail to identify an abnormality in approximately 15% to 30% of infertile couples. The reported incidence of such unexplained infertility varies according to the age and selection criteria in the study population. We conducted a review of the literature via MEDLINE. Articles were limited to English-language, human studies published between 1950 and 2013. Since first coined more than 50 years ago, the term unexplained infertility has been a subject of debate. Although additional investigations are reported to explain or define other causes of infertility, these have high false-positive results and therefore cannot be recommended for routine clinical practice. Couples with unexplained infertility might be reassured that even after 12 months of unsuccessful attempts, 50% will conceive in the following 12 months and another 12% in the year after.

Oocyte vitrification in the 21st century and post-warming fertility outcomes: a systematic review and meta-analysis.

Oocyte cryopreservation is a rapidly developing technology, which is increasingly being used for various medical, legal and social reasons. There are inconsistencies in information regarding survival rate and fertility outcomes. This systematic review and meta-analysis provides evidence-based information about oocyte survival and fertility outcomes post warming to help women to make informed choices. All randomized and non-randomized, controlled and prospective cohort studies using oocyte vitrification were included. The primary outcome measure was ongoing pregnancy rate/warmed oocyte. Sensitivity analysis for donor and non-donor oocyte studies was performed. Proportional meta-analysis of 17 studies, using a random-effects model, showed pooled ongoing pregnancy and clinical pregnancy rates per warmed oocyte of 7%. Oocyte survival, fertilization, cleavage, clinical pregnancy and ongoing pregnancy rates per warmed oocyte were higher in donor versus non-donor studies. Comparing vitrified with fresh oocytes, no statistically significant difference was observed in fertilization, cleavage and clinical pregnancy rates, but ongoing pregnancy rate was reduced in the vitrified group (odds ratio 0.74), with heterogeneity between studies. Considering the age of women and the reason for cryopreservation, reasonable information can be given to help women to make informed choices. Future studies with outcomes from oocytes cryopreserved for gonadotoxic treatment may provide more insight.

The measurement of anti-Müllerian hormone: a critical appraisal.

CONTEXT: Measurement of anti-Müllerian hormone (AMH) is perceived as reliable, but the literature reveals discrepancies in reported within-subject variability and between-method conversion factors. Recent studies suggest that AMH may be prone to preanalytical instability. We therefore examined the published evidence on the performance of current and historic AMH assays in terms of the assessment of sample stability, within-patient variability, and comparability of the assay methods. EVIDENCE ACQUISITION: We reviewed studies (manuscripts or abstracts) measuring AMH, published in peer-reviewed journals between January 1, 1990, and August 1, 2013, using appropriate PubMed/Medline searches. EVIDENCE SYNTHESIS: AMH levels in specimens left at room temperature for varying periods increased by 20% in one study and by almost 60% in another, depending on duration and the AMH assay used. Even at -20°C, increased AMH concentrations were observed. An increase over expected values of 20-30% or 57%, respectively, was observed after 2-fold dilution in two linearity-of-dilution studies, but not in others. Several studies investigating within-cycle variability of AMH reported conflicting results, although most studies suggest that variability of AMH within the menstrual cycle appears to be small. However, between-sample variability without regard to menstrual cycle as well as within-sample variation appears to be higher using the GenII AMH assay than with previous assays, a fact now conceded by the kit manufacturer. Studies comparing first-generation AMH assays with each other and with the GenII assay reported widely varying differences. CONCLUSIONS: AMH may exhibit assay-specific preanalytical instability. Robust protocols for the development and validation of commercial AMH assays are required.

Adjunct low-molecular-weight heparin to improve live birth rate after recurrent implantation failure: a systematic review and meta-analysis.

BACKGROUND Poor fertility outcomes in women with recurrent implantation failure (≥ RIF) present significant challenges in assisted reproduction, and various adjuncts, including heparin, are used for potential improvement in pregnancy rates. We performed this systematic review and meta-analysis to evaluate the effect of low-molecular-weight heparin (LMWH) on live birth rates (LBRs) and implantation rates (IRs) in women with RIF and undergoing IVF. METHODS Studies comparing LMWH versus control/placebo in women with RIF were searched for on MEDLINE, EMBASE, Cochrane Library, conference proceedings and databases for registered and ongoing trials (1980-2012). Statistical analysis was performed using Review Manager 5.1. The main outcome measure was LBR per woman. RESULTS Two randomized controlled trials (RCTs) and one quasi-randomized trial met the inclusion criteria. One study included women with at least one thrombophilia ( Qublan et al., 2008) and two studies included women with unexplained RIF ( Urman et al., 2009; Berker et al., 2011). Pooled risk ratios in women with ≥ 3 RIF (N = 245) showed a significant improvement in the LBR (risk ratio (RR) = 1.79, 95% confidence interval (CI) = 1.10-2.90, P = 0.02) and a reduction in the miscarriage rate (RR = 0.22, 95% CI = 0.06-0.78, P = 0.02) with LMWH compared with controls. The IR for ≥ 3 RIF (N = 674) showed a non-significant trend toward improvement (RR = 1.73, 95% CI 0.98-3.03, P = 0.06) with LMWH. However, the beneficial effect of LMWH was not significant when only studies with unexplained RIF were pooled. The summary analysis for the numbers needed to be treated with LMWH showed that approximately eight women would require treatment to achieve one extra live birth. CONCLUSIONS In women with ≥3 RIF, the use of adjunct LMWH significantly improves LBR by 79% compared with the control group; however, this is to be considered with caution, since the overall number of participants in the studies was small. Further evidence from adequately powered multi-centered RCTs is required prior to recommending LMWH for routine clinical use. This review highlights the need for future basic science and clinical research in this important field.

FSH receptor genotype does not predict metaphase-II oocyte output or fertilization rates in ICSI patients.

The objective of this study was to assess the role of the variant p.Asn680Ser in the FSH receptor gene (FSHR) in determining oocyte maturity. It also assessed the relationship between this FSHR variant with metaphase-II oocyte output rate (MOR) and the fertilization rate. This was a prospective observational study based at a tertiary referral centre for reproductive medicine. Women (n=212) undergoing their first cycle of ovarian stimulation for IVF with intracytoplasmic sperm injection (ICSI) were included in the study. Baseline pelvic ultrasound and blood tests were taken on day 2 or 3 of the cycle for assessment of baseline hormones and for DNA extraction. Genotypes for FSHR p.Asn680Ser was determined using TaqMan allelic discrimination assay. The outcome measures were the total dose of exogenous gonadotrophins used, antral follicle count (AFC), number of mature (metaphase-II) oocytes retrieved, MOR and fertilization rate. No statistically significant differences were found between the number of mature oocytes retrieved, MOR or fertilization rates among the patients with different p.Asn680Ser FSHR genotypes. No significant difference was noted in the clinical pregnancy rates per transfer. There is no evidence that the p.Asn680Ser FSHR genotype predicts oocyte maturity.

A common Asn680Ser polymorphism in the follicle-stimulating hormone receptor gene is not associated with ovarian response to gonadotropin stimulation in patients undergoing in vitro fertilization.

OBJECTIVE: To assess the role of the variant p.Asn680Ser in the follicle-stimulating hormone receptor (FSHR) gene in determining ovarian response in patients undergoing in vitro fertilization (IVF) treatment. DESIGN: Prospective observational study. SETTING: Tertiary referral center for reproductive medicine. PATIENT(S): Women (n = 421) undergoing their first cycle of controlled ovarian stimulation for IVF and 83 healthy, ethnically matched controls. INTERVENTION(S): Baseline pelvic ultrasound and blood tests taken on days 2 to 3 of the cycle for assessment of baseline hormones and for DNA extraction. MAIN OUTCOME MEASURE(S): Genotypes for FSHR p.Asn680Ser determined using TaqMan allelic discrimination assay, and ovarian response to gonadotropin treatment classified as normal, poor, or overresponse based on the number of oocytes retrieved. RESULT(S): The FSHR p.Asn680Ser genotype frequencies were similar in IVF patients and controls. The number of oocytes retrieved was comparable between patients with different FSHR receptor genotypes. The total amount of gonadotropin used was also similar in all the genotype groups. A logistic regression analysis showed nonstatistically significant twofold difference in the distribution of genotypes between the groups with poor and normal ovarian response. CONCLUSION(S): The variant FSHR p.Asn680Ser was not shown to be predictive of ovarian response, but clinically relevant differences cannot be ruled out.

Endometrial injury to overcome recurrent embryo implantation failure: a systematic review and meta-analysis.

Mechanical endometrial injury (biopsy/scratch or hysteroscopy) in the cycle preceding ovarian stimulation for IVF has been proposed to improve implantation in women with unexplained recurrent implantation failure (RIF). This is a systematic review and meta-analysis of studies comparing the efficacy of endometrial injury versus no intervention in women with RIF undergoing IVF. All controlled studies of endometrial biopsy/scratch or hysteroscopy performed in the cycle preceding ovarian stimulation were included and the primary outcome measure was clinical pregnancy rate. Pooling of seven controlled studies (four randomized and three non-randomized), with 2062 participants, showed that local endometrial injury induced in the cycle preceding ovarian stimulation is 70% more likely to result in a clinical pregnancy as opposed to no intervention. There was no statistically significant heterogeneity in the methods used, clinical pregnancy rates being twice as high with biopsy/scratch (RR 2.32, 95% CI 1.72-3.13) as opposed to hysteroscopy (RR 1.51, 95% CI 1.30-1.75). The evidence is strongly in favour of inducing local endometrial injury in the preceding cycle of ovarian stimulation to improve pregnancy outcomes in women with unexplained RIF. However, large randomized studies are required before iatrogenic induction of local endometrial injury can be warranted in routine clinical practice. Some women undergoing IVF treatment fail to conceive despite several attempts with good-quality embryos and no identifiable reason. We call this 'recurrent implantation failure' (RIF) where the embryo fails to embed or implant within the lining of the womb. Studies have shown that inducing injury to the lining of the womb in the cycle before starting ovarian stimulation for IVF can help improve the chances of achieving pregnancy. Injury can be induced by either scratching the lining of the womb using a biopsy tube or by telescopic investigation of the womb using a camera. We performed a collective review of the available good-quality studies that used the above two methods in the cycle prior to starting ovarian stimulation for IVF. We pooled results from seven studies, which included 2062 women with RIF and assessed the difference in clinical pregnancy rates for those undergoing injury to the womb lining compared with no injury prior to IVF. The results suggest that inducing injury is 70% more likely to result in a clinical pregnancy as opposed to no treatment. Furthermore, scratching of the lining was 2-times more likely to result in a clinical pregnancy compared with telescopic evaluation of the lining of the womb. This study suggests that in women with RIF, inducing local injury to the womb lining in the cycle prior to starting ovarian stimulation for IVF can improve pregnancy outcomes. However, large studies are required before this can be warranted in routine clinical practice.

Anti-Mullerian hormone: poor assay reproducibility in a large cohort of subjects suggests sample instability.

STUDY QUESTION: What is the variability of anti-Müllerian hormone (AMH) concentration in repeat samples from the same individual when using the Gen II assay and how do values compare to Gen I [Diagnostic Systems Ltd (DSL)] assay results? SUMMARY ANSWER: The Gen II AMH assay displayed appreciable variability, which can be explained by sample instability. WHAT IS KNOWN ALREADY: AMH is the primary predictor of ovarian performance and is used to tailor gonadatrophin dosage in cycles of IVF/ICSI and in other routine clinical settings. Thus, a robust, reproducible and sensitive method for AMH analysis is of paramount importance. The Beckman Coulter Gen II ELISA for AMH was introduced to replace earlier DSL and Immunotech assays. The performance of the Gen II assay has not previously been studied in a clinical setting. STUDY DESIGN, SIZE AND DURATION: We studied an unselected group of 5007 women referred for fertility problems between 1 September 2008 and 25 October 2011; AMH was measured initially using the DSL AMH ELISA and subsequently using the Gen II assay. AMH values in the two assays were compared using a regression model in log(AMH) with a quadratic adjustment for age. Additionally, women (n = 330) in whom AMH had been determined in different samples using both the DSL and Gen II assays (paired samples) identified and the difference in AMH levels between the DSL and Gen II assays was estimated using the age-adjusted regression analysis. A subset of 313 women had repeated AMH determinations (n = 646 samples) using the DSL assay and 87 women had repeated AMH determinations using the Gen II assay (n = 177 samples) were identified. A mixed effects model in log(AMH) was utilized to estimate the sample-to-sample (within-subject) coefficients of variation of AMH, adjusting for age. Laboratory experiments including sample stability at room temperature, linearity of dilution and storage conditions used anonymized samples. MAIN RESULTS AND THE ROLE OF CHANCE: In clinical practice, Gen II AMH values were ∼20% lower than those generated using the DSL assay instead of the 40% increase predicted by the kit manufacturer. Both assays displayed high within-subject variability (Gen II assay CV = 59%, DSL assay CV = 32%). In the laboratory, AMH levels in serum from 48 subjects incubated at RT for up to 7 days increased progressively in the majority of samples (58% increase overall). Pre-dilution of serum prior to assay, gave AMH levels up to twice that found in the corresponding neat sample. Pre-mixing of serum with assay buffer prior to addition to the microtitre plate gave higher readings (72% overall) compared with sequential addition. Storage at -20°C for 5 days increased AMH levels by 23% compared with fresh samples. The statistical significance of results was assessed where appropriate. LIMITATIONS, REASONS FOR CAUTION: The analysis of AMH levels is a retrospective study and therefore we cannot entirely rule out the existence of differences in referral practices or changes in the two populations. WIDER IMPLICATIONS OF THE FINDINGS: Our data suggests that AMH may not be stable under some storage or assay conditions and this may be more pronounced with the Gen II assay. The published conversion factors between the Gen II and DSL assays appear to be inappropriate for routine clinical practice. Further studies are urgently required to confirm our observations and to determine the cause of the apparent instability. In the meantime, caution should be exercised in the interpretation of AMH levels in the clinical setting. CONFLICT OF INTEREST/STUDY FUNDING: S. Roberts is supported by the NIHR Manchester Biomedical Research Centre.

PCOS and peripheral AMH levels in relation to FSH receptor gene single nucleotide polymorphisms.

OBJECTIVES: To determine if an association exists between the follicle-stimulating hormone receptor (FSHR) gene p.Asn680Ser polymorphism and polycystic ovary syndrome (PCOS) or with high anti-mullerian hormone (AMH) levels without PCOS. PATIENTS: Fifty-eight women with PCOS, 24 women with high AMH (>44.5 pmol/L) without PCOS and 80 healthy ethnically matched female controls. MAIN OUTCOME MEASURES: Prevalence of the FSHR p.Asn680Ser polymorphism, baseline serum AMH levels and response to ovulation induction with clomiphene citrate. RESULTS: The frequency of FSHR p.Asn680Ser genotypes were not significantly different between PCOS patients, patients with high AMH without PCOS and controls (p = 0.88). Of the women with PCOS, 34/58 were on clomiphene citrate treatment and 12/34 were resistant. There was no association between sensitivity or resistance to clomiphene and p.Asn680Ser genotypes (p = 0.38). CONCLUSIONS: There is no evidence that FSHR p.Asn680Ser genotypes are associated with PCOS, high AMH levels or response to clomiphene citrate.

Follicle-stimulating hormone receptor gene polymorphisms are not associated with ovarian reserve markers.

OBJECTIVE: To evaluate the association between variants in the FSHR receptor (FSHR) gene and current markers of ovarian reserve (antimüllerian hormone, antral follicle count, FSH). DESIGN: Prospective observational study. SETTING: Tertiary referral center for reproductive medicine. PATIENT(S): Women (n = 421) undergoing their first cycle of controlled ovarian stimulation for IVF. INTERVENTION(S): Baseline pelvic ultrasound and blood tests were taken on day 2-3 of the cycle for assessment of baseline hormones and for DNA extraction. Genotypes for FSHR p.Asn680Ser and p.Thr307Ala variants were determined using TaqMan allelic discrimination assays. MAIN OUTCOME MEASURE(S): Association of FSHR single nucleotide polymorphisms with markers of ovarian reserve. RESULT(S): There was no evidence of any difference in basal FSH, antimüllerian hormone, or antral follicle count between the patients with different genotypes, with or without an adjustment for age or body mass index. CONCLUSION(S): No associations of FSHR genotypes with markers of ovarian reserve were detected in our cohort.

Conventional ovarian stimulation no longer exists: welcome to the age of individualized ovarian stimulation.

The prediction of extremes of ovarian response to stimulation and the irreversibility of reduced ovarian reserve remain important clinical and basic science research issues of IVF treatment. Recommending commencement of ovarian stimulation using any of the available exogenous compounds without knowledge of individual ovarian potentials is simplistic and dangerous because of the possible adverse consequences for the woman. The identification of groups of patients likely to benefit from one protocol than another is central to the workup process of IVF. Determining the agents for ovarian stimulation as well as the combination of them, the daily dose and duration according to some background information should be seen as the way to enhance safety and cost-effectiveness. This discussion paper aims to introduce the concept of individualized ovarian stimulation in routine clinical practice and to generate interest for tailored stimulation protocols.

Evidence-based management of endometrioma.

Endometrioma is commonly seen in women of reproductive age who may wish to preserve their ovarian function. Surgical treatment is associated with a high recurrence rate and its employment for women undergoing assisted conception has recently been challenged. Medical treatment has not been shown to be effective in controlling symptoms or improving fertility potential. The results of retrospective and non-randomized studies have been inconsistent and created an ongoing debate between gynaecologists and fertility specialists. This manuscript reviews and critically appraises the evidence for management of endometrioma in women of reproductive age. In asymptomatic women, surgical treatment is usually recommended for women above the age of 40 and for large endometriomas. Except for pelvic clearance, there is insufficient evidence to suggest that surgical treatment of endometrioma is better than medical treatment with respect to the long-term relief of symptoms and quality of life. Laparoscopic excision of ovarian endometrioma prior to IVF does not offer any additional benefit over expectant management. A large, well-designed, adequately powered randomized controlled study that compares the effects of surgical removal versus expectant management of endometrioma on ovarian performance and pregnancy outcomes in women undergoing IVF is warranted.

Age-related normograms of serum antimüllerian hormone levels in a population of infertile women: a multicenter study.

OBJECTIVE: To produce age-related normograms for serum antimüllerian hormone (AMH) level in infertile women without polycystic ovaries (non-PCO). DESIGN: Retrospective cohort analysis. SETTING: Fifteen academic reproductive centers. PATIENT(S): A total of 3,871 infertile women. INTERVENTION(S): Blood sampling for AMH level. MAIN OUTCOME MEASURE(S): Serum AMH levels and correlation between age and different percentiles of AMH. RESULT(S): Age-related normograms for the 3rd, 10th, 25th, 50th, 75th, 90th, and 97th percentiles of AMH were produced. We found that the curves of AMH by age for the 3rd to 50th percentiles fit the model and appearance of linear relation, whereas the curves of >75th percentiles fit cubic relation. There were significant differences in AMH and FSH levels and in antral follicle count (AFC) among women aged 24-33 years, 34-38 years, and ≥39 years. Multivariate stepwise linear regression analysis of FSH, age, AFC, and the type of AMH kit as predictors of AMH level shows that all variables are independently associated with AMH level, in the following order: AFC, FSH, type of AMH kit, and age. CONCLUSION(S): Age-related normograms in non-PCO infertile women for the 3rd to 97th percentiles were produced. These normograms could provide a reference guide for the clinician to consult women with infertility. However, future validation with longitudinal data is still needed.

Live birth rate in fresh and frozen embryo transfer cycles in women with endometriosis.

OBJECTIVES: To test the hypothesise that the treatment protocol used for preparation of the endometrium for frozen embryo transfer (ET) has a beneficial effect on the disorganised endometrium in women with endometriosis and leads to a higher pregnancy rate. STUDY DESIGN: We performed a retrospective, database-searched cohort study. Relevant information was collected from the electronic records of women who underwent IVF/ICSI between 1/1/2000 and 31/12/2008 in our unit. Endometriosis patients formed the study group. The rest of the women formed the control group. The two groups were subdivided, depending on whether they had fresh or frozen ET. The main outcome was live birth rate (LBR). Secondary outcomes were clinical pregnancy rate (CPR) and miscarriage rate (MR). Comparisons were performed by Chi-square and Mann-Whitney tests (SPSS 16.0). RESULTS: A total of 3763 fresh and 3523 frozen ET IVF cycles were included in our study, of which 415 (5.7%) were due to endometriosis related subfertility. In the non-endometriosis group, fresh ET had significantly higher LBR, CBR and MR than frozen ET. In women with endometriosis, down-regulated frozen ET cycles had a markedly high LBR and CPR (16.9%, 18.2%), comparable to the LBR and CPR of fresh ET cycles in the same group (19.5%, 20.2%). No significant differences were found in the LBR and CPR in fresh ET cycles between the study and the control group. In frozen ET, however, the CPR was significantly higher in the endometriosis group (18.2% versus 12.7%, P=0.048). CONCLUSION: Unlike the general IVF population, in women with endometriosis undergoing IVF, the preparation of the endometrium for frozen ET with GnRH agonists compared to fresh cycles is associated with higher LBR (16.9% versus 11.9%) and a significantly higher CPR (18.2% versus 12.7%, P=0.048). These results suggest that, in cases of endometriosis, the combined effect of GnRHa on the endometrium and the low level of ovarian steroids may simultaneously offer a better endometrial environment for implantation which may lead to better outcomes.