{"paper_id":"e14d0676-5735-48fe-986e-aa6f08df2a0c","body_text":"Original Article \nInfluence of endometriosis on the outcomes of assisted reproductive technology in poor \novarian responders with previous implantation failures \n \nSoojin Oh, DEGREE1, Seula Lee, DEGREE1, Sungwook Chun, MD, PhD1*, Tae Woo Park, DEGREE2, Jae \nHong Joo, DEGREE2, Yun Hee Koo, DEGREE2*, Yong Chan Lee, DEGREE2  \n \n1Department of Obstetrics and Gynecology, Inje University Haeundae Paik Hospital, 2Busan Maria \nFertility Center, Busan, Korea \n \nRunning title: Endometriosis effect on ART in PORs \n \nReceived: 2026.05.22. \nRevised: 2026.07.10. \nAccepted: 2026.08.11. \n \nCorresponding author: Sungwook Chun, MD, PhD \nDepartment of Obstetrics and Gynecology, Inje University Haeundae Paik Hospital, 875 Haeun-daero, \nHaeundae-gu, Busan 48108, Korea \nE-mail: wooki1974@empal.com \nhttps://orcid.org/ \n*These authors contributed equally and share corresponding authorship. \n \n  \n\n \n \nABSTRACT \nObjective \nTo evaluate whether endometriosis (EMS) adversely affects the embryological and clinical outcomes \nof assisted reproductive technology (ART) in poor ovarian responders (PORs) with repeated \nimplantation failure undergoing spindle view-assisted intracytoplasmic sperm injection (SV-ICSI). \nMethods \nThis retrospective study included women aged 35 -44 years who underwent ART with SV -ICSI at a \nsingle fertility center between January 2023 and December 2024. All participants fulfilled the Bologna \ncriteria for POR and had experienced at least three previous failed embryo transfer cycles. Patients \nwith laparoscopically confirmed EMS were assigned to the EMS group (n=36), whereas age-matched \npatients without a history or ultrasonographic evidence of EMS were selected as controls in a 1:3 \nratio (n=108).  \nResults \nThe baseline characteristics were comparable between the two groups. No significant differences \nwere observed between the EMS and control groups in key embryological parameters including \nfertilization rate, cleavage rate, good -quality cleavage embryo rate, and blastocyst formation rate . \nSimilarly, ART-related clinical outcomes did not differ significantly between the two groups, including \nimplantation rate (13.0% vs. 11.7%), clinical pregnancy rate (19.4% vs. 18.5%), and clinical abortion \nrate (28.6% vs. 40.0%). \nConclusion \nIn this retrospective cohort of patients  with POR with repeated implantation failure, no statistically \nsignificant association was found between EMS and embryological or ART-related clinical outcomes. \nHowever, given the limited sample size and reliance on surrogate reproductive endpoints, these \nfindings should be considered preliminary and hypothesis  generating and require confirmation in \nlarger prospective studies incorporating live birth outcomes.  \n \n\n \n \nKeywords: Endometriosis; Poor ovarian response; Repeated implantation failure; Assisted \nreproductive technology; Intracytoplasmic sperm injection \n  \n\n \n \n \nIntroduction  \nEndometriosis (EMS) is a chronic inflammatory gynecological disorder characterized by the presence \nof endometrial-like tissue outside the uterine cavity and affects approximately 10% of women of \nreproductive age [1-3]. EMS is a prevalent yet debilitating condition that is strongly associated with \ninfertility, making it one of the most common gynecologic  disorders related to infertility [1,2,4]. \nSeveral mechanisms have been proposed to explain EMS -associated infertility, including chronic \nperitoneal inflammation [5 ,6], oxidative stress and an altere d follicular microenvironment [7 ], \nimpaired follicular development and reduced oocyte quality [8], and altered endometrial receptivity \n[9]. \nSince the first successful birth following in vitro  fertilization (IVF) in 1978, assisted \nreproductive technology (ART) has become a fundamental therapeutic option for women with \ninfertility who fail to conceive spontaneously. Advances in ovarian stimulation protocols, embryo \nculture systems, and micromani pulation techniques, particularly intracytoplasmic sperm injection \n(ICSI), have expanded the indications for ART to include women with repeated implantation failure, \ndiminished ovarian reserve, and advanced maternal age. \nPoor ovarian responders (PORs) represent a clinically challenging subgroup among women \nundergoing ART. The Bologna criteria were proposed to standardize the definition of POR by \nincorporating advanced maternal age, abnormal ovarian reserve markers, and reduced responses to \nprevious ovarian stimu lation, and remain the most widely accepted and internationally validated \ndefinition of POR  [10]. More recently, the POSEIDON classification was introduced to further \nindividualize the prognosis and treatment strategies for patients with a low  prognosis undergoing \nART [11]. POR patients generally exhibit fewer retrieved oocytes, limited embryo availability, and \nlower clinical pregnancy rates than normal responders, even when optimized stimul ation strategies \nare applied [12]. \nART outcomes in POR patients may be influenced by multiple factors, including maternal \n\n \n \nage, ovarian reserve parameters, stimulation protocols, embryo quality, and gynecologic di seases \nsuch as EMS [13-15]. However, the effect of coexisting gynecologic conditions, particularly EMS, on \nART outcomes in this population remains controversial. \nSeveral studies have reported impaired ovarian reserve  in women with EMS, reflected by \ndecreased anti-Müllerian hormone (AMH) levels and antral follicle counts (AFC s), particularly in the \npresence of ovarian endo metriomas [16,17 ]. Surgical excision of endometriomas has also been \nconsistently associated with  postoperative decline s in ovarian reserve markers [14,18 -20]. \nFurthermore, experimental and clinical studies have suggested possible reductions in fertilization \nrates and oocyte quality in patients with EMS, potentially mediated by inflammatory c ytokines and \noxidative stress [7-9]. \nConversely, other studies and meta -analyses have demonstrated comparable fertilization \nrates, embryo quality, and pregnancy outcomes between patients with and without EMS undergoing \nART, particularly when key pelvic factors are bypassed [15,21]. Large population-based analyses have \nfurther suggested that isolated EMS may not independently compromise live birth rates after IVF \nand that adverse outcomes are often confounded by conco mitant infertility diagnoses [13 ]. These \nconflicting findings suggest that the detrimental effects of EMS on ART outcomes may be context -\ndependent and influenced by patient characteristics , such as ovarian reserve status and prior \nimplantation history. Importantly, evidence focusing specifically on patients with POR with repeated \nimplantation failure remains limited. \nSpindle view-assisted ICSI (SV-ICSI) was introduced as an advanced micromanipulation \ntechnique that enables visualization of the meiotic spindle  (MS), potentially minimizing oocyte \ndamage and optimizing sperm injection orientation. MS morphology is correlated with fertilization, \nblastocyst development, and euploidy rates [21]. Given the previous reports of spindle abnormalities \nand oxidative damage in oocytes from women with EMS [5,7,21,22], this approach may be particularly \nrelevant in patients with POR, whose oocyte quality is often compromised. \nTherefore, the present study was conducted to evaluate the effect of EMS on embryological \n\n \n \nparameters and ART-related clinical outcomes in patients with POR with repeated implantation failure \nwho underwent SV-ICSI. By comparing age-matched patients with POR with and without EMS, we \naimed to clarify whether EMS should be considered a prognostic factor for ART success in this highly \nselected patient population.  \n \n \nMaterials and methods  \n1. Patients \nThis retrospective study included women aged 35 -44 years who underwent ART with SV -ICSI at a \nsingle fertility center between January 2023 and December 2024. The study was approved by the \nInstitutional Review Board of the fertility hospital, which waived the requirement for informed \nconsent owing to the retrospective nature of the study. \nPoor ovarian response (POR) was defined according to the Bologna criteria [10] as the \npresence of at least two of the following three features: 1) advanced maternal age (≥40 years) or \nany other risk factor for POR; 2) a previous episode of POR, defined as a cancelled cycle or retrieval \nof ≤3 oocytes following conventional ovarian sti mulation; and 3) an abnormal ovarian reserve test, \ndefined as an AFC <7 follicles or an AMH level <1.1 ng/mL . In addition, two episodes of POR after \nmaximal ovarian stimulation were considered sufficient to define POR in the absence of advanced \nmaternal age or abnormal ovarian reserve test results [9]. Among women with POR, those with a \nhistory of at least three failed embryo transfer cycles were included in the study [2 3,24]. All study \nparticipants underwent SV -ICSI and fresh embryo transfer cycles. Those who underwent complete \nembryo cryopreservation after oocyte retrieval were excluded from this study. \nThe study population was classified into an EMS group and a non -EMS group. The EMS \ngroup included patients with laparoscopically confirmed EMS. The non-EMS group included patients \nwith no prior diagnosis of EMS or ultrasonographic findings suggestive of EMS. Controls were \nselected from the eligible non-EMS population using age matching at a 1:3 ratio. For each patient \n\n \n \nin the EMS group, three controls were randomly selected from the age -matched non-EMS pool \nusing a random number generator. A total of 144 women were included in the final analysis: 36 in \nthe EMS group and 108 in the non-EMS group. \n \n2. Procedures [24] \nOocyte retrieval was performed either during a natural cycle or after controlled ovarian stimulation. \nControlled ovarian stimulation was conducted using recombinant follicle -stimulating hormone, \nincluding Follitrope® (LG Life Science, Seoul, Korea), Gonal -F® (Serono, Istanbul, Turkey), or human \nmenopausal gonadotropin (IVF-M HP®; LG Life Science). Ovarian stimulation protocols consisted of \neither a long gonadotropin -releasing hormone (GnRH) agonist regimen or a GnRH antagonist \nregimen. Final oocyte maturation was induced using recombinant human chorionic gonadotropin \n(Ovidrel®; Merck KGaA, Darmstadt, Germany) or a GnRH agonist (Decapeptyl ®; Ferring, Malmo, \nSweden) once the leading follicles reached an appropriate diameter. To maximize the fertilization \nrate, all retrieved oocytes were fertilized using SV-ICSI, exclusively [24].  \nSV-ICSI was performed uniformly in all participants to optimize fertilization outcomes \nand minimize procedural variability. Based on evidence demonstrating a higher proportion of good-\nquality embryos with SV -ICSI than with conventional ICSI [24,25], our in stitution has adopted this \ntechnique as the standard fertilization method for all POR patients since 2023. \nFor SV-ICSI, metaphase II oocytes with a visible first polar body (PB) were transferred into \nwarm ICSI medium (MRC#ICSI ; MARIA Research Center, Seoul, Korea) during micromanipulation. \nSperm injection was performed under an inverted microscope (IX73; Olympus, Tokyo, Japan) \nequipped with polarized light microscopy  and a heated stage maintained at 36.5 -37.5°C. The MS \nand PB were identified and aligned before sperm injection. To optimize spindle visualization, oocytes \nwere gently rotated using holding and injection pipettes until the clearest spindle image was \nobtained. When the spindle was visualized, sperm were injected with the spindle positioned in the \n0 o’clock direction. When the spindle could not be visualized, an injection needle was introduced at \n\n \n \nthe 3 o’clock position while the PB was positioned at 0 o’clock . Fig. 1 illustrates MS localization in \nliving human metaphase II oocytes using the inverted method according to the angle of deviation \nrelative to the PB position. After microinjection, oocytes were cultured individually in equilibrated \nculture medium (MRC#ID16 ; MARIA Research Center) at 37°C in an incubator containing 5% CO₂  \n[24].  \n \n3. Measures of ART-related embryological and clinical outcomes [24] \nEmbryological and clinical outcomes were compared between the EMS and non -EMS groups. The \nevaluated outcomes included fertilization, cleavage, good -quality cleavage embryo, blastocyst \nformation, good-quality blastocyst, implantation, clinical pregnancy, and clinical abortion rates [24]. \nThe fertilization rate was defined as the proportion of injected oocytes that formed two \npronuclei. The cleavage rate was defined as the number of day 3 embryos divided by the total \nnumber of fertilized oocytes. A good-quality cleavage embryo was defined as an embryo with more \nthan five regular blastomeres and <10% fragmentation on day 3. The good-quality cleavage embryo \nrate was calculated as the number of good -quality cleavage embryos divided by the total number \nof fertilized oocytes. Blastocyst formation rate was defined as the number of embryos that developed \nto the blastocyst stage divided by the total number of fertilized oocytes.  \nImplantation rate was defined as the number of gestational sacs confirmed by \ntransvaginal ultrasonography divided by the number of embryos transferred. Clinical pregnancy was \ndefined as the presence of at least one gestational sac on transvaginal ultrasono graphy, and the \nclinical pregnancy rate was calculated as the number of transfer cycles resulting in clinical pregnancy \ndivided by the total number of transfer cycles. The clinical abortion rate was defined as the number \nof pregnancy losses, including ecto pic pregnancies, before 20 weeks of gestation divided by the \ntotal number of clinical pregnancies [24]. \n \n4. Statistical analysis \n\n \n \nContinuous variables are presented as mean±standard deviation, and categorical variables are \npresented as number (percentage). Comparisons between the EMS and control groups were \nperformed using an unpaired t-test for continuous variables and the chi-square test or Fisher’s exact \ntest for categorical variables, as appropriate. Multivariable logistic regression analysis was performed \nto evaluate the independent association between EMS and clinical outcomes related to ART and \nembryo quality. EMS was entered as the primary independent variable, and age, body mass index  \n(BMI), AMH level, number of retrieved oocytes, and number of transferred embryos were included \nas adjustment variables because these variables are well-established determinants of ART outcomes \nand are considered potential confounders based on their established clinical relevance.  \nAll statistical analyses were performed using IBM SPSS Statistics version 25.0 (IBM Corp., \nArmonk, NY, USA). A two-sided P-value <0.05 was considered statistically significant.  \n \n \nResults \nFig. 2 shows the distribution of MS positions relative to the PB position based on the angle of \ndeviation in the EMS and control groups. The distribution of MS orientation did not differ \nsignificantly between the two groups (P=0.485), indicating comparable spindle orientation patterns \nduring SV-ICSI and suggesting that procedural differences in spindle visualization were unlikely to \naccount for differences in embryological or clinical outcomes. \nTable 1 presents a comparison of the baseline clinical characteristics between the EMS group \nand control group. No significant differences were observed between the two groups in terms of \nage, parity, BMI, basal AMH levels, number of previous implantation failures, total gonadotropin \ndosage, endometrial thickness on trigger day, number of retrieved oocytes, or number of transferred \nembryos (all P>0.05). In addition, the distribution of superovulation methods, premature LH surge \nprevention protocols, and proportion of blastocyst transfer cycles were comparable between the \nEMS and control groups.  \n\n \n \nTable 2 summarizes the embryological and clinical outcomes according to the presence of EMS. The \nfertilization rate was comparable between the EMS and control groups (76.2% vs. 78.9% ; P=0.498). \nSimilarly, no significant differences were observed in the cleavage rate (96.3% vs. 96.6% ; P=0.776), \ngood-quality cleavage embryo rate (55.0% vs. 55.6% ; P=0.924), or blastocyst formation rate (23.9% \nvs. 21.7%; P=0.638). Clinical outcomes were also similar between the two groups. The implantation \nrate did not significantly differ between the EMS and control groups (13.0% vs. 11.7%; P=0.797), and \ncomparable clinical pregnancy rates were observed (19.4% vs. 18.5% ; P=0.902). Furthermore, the \nclinical abortion rate was not significantly different between the groups (28.6% vs. 40.0%; P=0.678).  \nAfter adjusting for age, BMI, AMH level , number of retrieved oocytes, and number of \ntransferred embryos, EMS was not independently associated with clinical pregnancy outcomes (OR, \n0.795; 95% CI, 0.284-2.224; P=0.662). \n \n \nThe present study was conducted to clarify whether EMS independently affects ART outcomes in a \nparticularly vulnerable population -PORs with a history of repeated implantation failure.  This \nsubgroup represents a clinical scenario in which both embryo competence and implantation \npotential are already compromised, making the additional impact of EMS a critical concern in \ntreatment decision -making and patient counseling. In this retrospective cohort of women who \nunderwent SV-ICSI, EMS was not associated with adverse embryologic al or clinical outcomes. Key \nparameters, including fertilization rate, cleavage rate, good-quality embryo rate, blastocyst formation \nrate, implantation rate, and clinical pregnancy outcomes , were comparable between patients with \nand without EMS.  \nIn the present study, POR was defined according to the Bologna criteria, which are the \nmost widely accepted diagnostic criteria for POR. Although the POSEIDON classification provides a \nmore refined prognostic stratification for patients with low prognosis undergoing ART, the present \nDiscussion \n\n \n \nstudy adopted the Bologna criteria because they remain the most widely accepted and \ninternationally validated diagnostic criteria for POR. Because this was a retrospective study, the \ncomplete clinical information required for accurate POSEIDON stratification was not consistently \navailable for all patients.  \nAlthough EMS is a well -established cause of infertility  [5-8,26,27], whether these \npathophysiological alterations translate into poorer ART outcomes remains controversial. \nImportantly, many pathophysiological processes implicated in EMS-associated infertility [8] primarily \naffect natural conception and are partially bypassed during ICSI-based ART. \nSeveral previous studies have reported findings consistent with ours, suggesting that EMS \nitself does not independently compromise ART outcomes. Large population -based analyses and \nrecent reviews have shown that fertilization, embryo development, implantation, and pregnancy \noutcomes are generally comparable between women with and without EMS once ovarian reserve \nand the effects of previous ovarian surgery are considered [13,15,19].  \nIn contrast, several studies have reported poorer ART outcomes in women with advanced -\nstage EMS or ovarian involvement [1 4]. Meta -analyses have suggested lower implantation and \nclinical pregnancy rates in patients with stage III/IV disease, while reductions in ovarian reserve \nassociated with advanced disease and previous ovarian surgery have also been consistently \ndocumented [16-18]. These findings suggest that the adverse ART outcomes reported in some \nstudies may largely reflect reduced ovarian reserve or the effects of prior ovarian surgery , rather \nthan the independent effect of EMS itself. The discrepancy between these studies and our findings \nmay therefore be explained by differences in disease severity, surgical history, patient selection, and \nstudy design. Furthermore, because all the participants in the present study were PORs with repeated \nimplantation failure who underwent SV -ICSI, the dominant determinants of treatment outcomes \nwere likely diminished oocyte quantity and intrinsic embryo competence, potentially attenuating the \nrelative contribution of EMS. \nSeveral limitations of this study should be considered.  \n\n \n \nFirst, three limitations may have collectively reduced our ability to detect true difference s \nbetween the EMS and non -EMS groups. The relatively small number of patients with EMS and the \nlimited number of clinical pregnancy events may have reduced the statistical power to detect \nclinically meaningful differences between the groups. In addition, because the number of outcome \nevents was limited relative to the number of covariates i ncluded in the multivariable logistic \nregression model, the adjusted estimate s should be interpreted with caution owing to the limited \nstability and precision of the model . The relatively wide confidence intervals observed in the \nregression analysis further reflect the limited precision of the estimated effect sizes. The possibility \nof disease misclassification should also be considered. Women in the control group were classified \nbased on the absence of a previous diagnosis and the absence of ultrasonographic findings \nsuggestive of EMS; however, diagnostic laparoscopy was not routinely performed in these patients. \nTherefore, some women may have had undiagnosed minimal or superficial peritoneal EMS that was \nnot detectable by ultrasonography and remained unrecognized. Such nondifferential \nmisclassification would have likely biased the comparison toward the null and may have attenuated \ntrue differences between the groups. Another related limitation is the reliance on surrogate \nreproductive endpoints. As most patients were referred to outside obstetric centers after \napproximately 15 weeks of gestation for antenatal care and delivery, prospective assessment of live \nbirth outcomes was not feasible in the present study. Accordingly, implantation and clinical \npregnancy were used as surrogate reproductive outcomes, although live birth  remains the most \nclinically meaningful outcome measure  in ART research. This limitation is particularly important \nbecause EMS may influence reproductive outcomes beyond implantation and early clinical \npregnancy, including late pregnancy loss and obstetric complications [28,29]; therefore, surrogate \nendpoints such as implantation and clinical pregnancy rates may not fully capture  the potential \nreproductive effects of EMS. Taken together, these limitations may operate in the same direction: \nlimited statistical power may reduce the ability to detect an existing difference, misclassification of \nwomen with undiagnosed EMS into the control group may dilute the contrast between the groups, \n\n \n \nand reliance on early surrogate endpoints may fail to capture differences emerging later in \npregnancy. Therefore, their combined effects may bias the findings toward the null. Consequently, it \nremains difficult to determine whether the observed lack of statistically significant associations \nreflected a genuine absence of an effect of EMS or whether the true effect was masked by the \ncombined influence of these limitations. \nSecond, because this study was conducted at a single fertility center, many patients had \npreviously undergone EMS surgery at outside institutions, making detailed operative records, \nincluding accurate EMS staging and prior surgical details such as ovarian cystectomy, unavailable. \nConsequently, important clinical information, including the presence of deep infiltrating EMS, rASRM \nstage, ovarian endometrioma characteristics, and details of previous ovarian surgery  such as \ncystectomy, was unavailable because of the retrospective nature of this study. Therefore, subgroup \nanalysis based on disease severity and evaluation of the independent effects of previous ovarian \nsurgery on ovarian reserve and ART outcomes could not be fully evaluated.  \nThird, selection bias may have been present because only patients who underwent fresh \nembryo transfer were included in the analysis, whereas cycles involving elective embryo \ncryopreservation were excluded. Given the increasing use of frozen embryo transfer in contemporary \nART practice, this selection may limit the generalizability of our findings. Future prospective studies \nthat include both fresh and frozen embryo transfer cycles with live birth  as the primary endpoint \nare warranted. \nFourth, the retrospective design limited our ability to fully evaluate other potential \ncontributors to POR, including autoimmune and systemic inflammatory conditions. Hence, \nheterogeneity in ovarian stimulation protocols should also be considered when interpreting the \nresults. Although subgroup analyses according to stimulation protocols may have provided \nadditional insights, such analyses were not feasible because of the limited sample size and \ninsufficient statistical power. \nIn summary, our study did not identify a statistically significant association between \n\n \n \nconcomitant EMS and embryological or ART -related clinical outcomes in PORs with repeated \nimplantation failure. Given the retrospective design, limited sample size, and single -center setting, \nthese findings should be interpreted with caution and should not be considered definitive evidence \nof the absence of an effect. Rather, th is study should be regarded as hypothesis generating and \nshould serve as a basis for future large-scale prospective investigations. \n \n \n \nConflict of interest  \nThe authors declare no conflict of interest. \n \nEthical approval   \nThe study was conducted in accordance with the guidelines of the Declaration of Helsinki. Thi\ns retrospective study was approved by the Institutional Review Board (IRB) of Maria Fertility H\nospital (IRB No. HR -2026-56-01). \n \nPatient consent \nThe requirement for informed consent was waived due to the retrospective nature of the stud\ny and the guaranteed anonymity of the participants.  \n \nFunding information  \nThis research received no external funding.   \n\n \n \nREFERENCES  \n1. Vanhie A. Endometriosis. In: Berek JS, editor. Berek & novak’s gynecology. 17th ed. CITY: \nCOMPANY; 2026. p.289-324.  \n2. Lee HJ, Yoon SH, Lee JH, Chung YJ, Park SY, Kim SW, et al. Clinical evaluation and \nmanagement of endometriosis: 2024 guideline for Korean patients from the Korean Society of \nEndometriosis. Obstet Gynecol Sci 2025;68:43-58. \n3. Becker CM, Bokor A, Heikinheimo O, Horne A, Jansen F, Kiesel L, et al. ESHRE guideline: \nendometriosis. Hum Reprod Open 2022;2022:hoac009. \n4. Practice Committee of the American Society for Reproductive Medicine. 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Association between endometriosis and adverse \nreproductive and perinatal outcomes in women undergoing assisted reproductive technology: a \nsystematic review and meta-analysis. Front Med (Lausanne) 2026;13:1630529. \n29. Busnelli A, Di Simone N, Somigliana E, Greppi D, Cirillo F, Bulfoni  A, et al. Untangling the \nindependent effect of endometriosis, adenomyosis, and ART -related factors on maternal, placental, \nfetal, and neonatal adverse outcomes: results from a systematic review and meta -analysis. Hum \nReprod Update 2024;30:751-88. \n  \n\n \n \n \n \n \nFig. 1. Spindles in living human metaphase II oocytes imaged using the inverted method according \nto the angles of deviation relative to the position of the polar body. (A) 0 o’ clock, (B) 3 o’ clock, (C) \nspindle invisible. PB, polar body.  \n \n \n  \n\n\n \n \n \n \n \nFig. 2. Meiotic spindle distribution according to the angles of deviation relative to the position of \nthe polar body between poor ovarian responders with and without endometriosis. (A) 0 o’ clock, (B) \n1 o’ clock, (C) 2 o’ clock, (D) 3 o’ clock, (E) 4 o’ clock, (F) 5 o’ clock, (G) 6 o’ clock, (H) spindle invisible. \nEMS, endometriosis.   \n \n  \n\n\n \n \nTable 1. Comparison of baseline clinical and cycle characteristics between poor ovarian responders \nwith and without endometriosis  \n Endometriosis \ngroup (n=36) \nControl group \n(n=108) \nP-value \nAge (yr) 41.67±2.14 41.67±2.12 1.000a \nParity 0.11±0.32 0.20±0.47 0.187a \nBody mass index (kg/m2) 22.31±4.46 23.54±5.50 0.187a \nBasal AMH levels (ng/mL) 0.77±0.62 0.87±0.87 0.535a \nNumber of previous implantation \nfailures \n4.33±2.51 4.31±2.31  0.968a \nTotal gonadotropin dosage 3,175.71±1,103.91 3,555.02±1,142.05  0.088a \nEndometrial thickness on the trigger \nday (mm) \n9.11±1.41 9.57±1.99 0.133a \nRetrieved oocytes 5.58±4.10 7.12±5.01 0.099a \nTransferred embryos 1.50±0.65 1.67±0.66 0.377a \nSuperovulation methods   0.108b \nNatural  4/36 (11.1) 4/108 (3.7)  \nControlled ovarian hyperstimulation 32/36 (88.9)  104/108 (96.3)  \nPremature LH surge preventiond     0.740b \nGnRH agonist 4/32 (12.5) 10/104 (9.6)  \nGnRH antagonist 28/32 (87.5)  94/104 (90.4)  \nPercentage of blastocyst transfer 9/36 (25.0) 27/108 (25.0) 1.000c \nValues are presented as mean±standard deviation or number (%). \nAMH, anti-Müllerian hormone; GnRH, gonadotropin-releasing hormone. \naP-value by unpaired t-test. \nbP-value by Fisher’s exact test. \ncP-value by chi-square test. \ndIncluded only patients who underwent controlled ovarian stimulation. Patients undergoing natural \ncycle assisted reproductive technology were excluded. \n  \n\n \n \nTable 2. Comparison of embryological and clinical outcomes between poor ovarian responders with \nand without endometriosis  \n Endometriosis group \n(n=36) \nControl group (n=108) P-value \nFertilization rate 109/143 (76.2) 414/525 (78.9) 0.498a \nCleavage rate 105/109 (96.3) 400/414 (96.6) 0.776b \nGood-quality cleavage \nembryo rate \n60/109 (55.0) 230/414 (55.6) 0.924a \nBlastocyst rate 26/109 (23.9) 90/414 (21.7) 0.638a \nImplantation rate 7/54 (13.0) 21/180 (11.7) 0.797a \nClinical pregnancy rate 7/36 (19.4) 20/108 (18.5) 0.902a \nClinical abortion rate 2/7 (28.6) 8/20 (40.0) 0.678b \nValues are presented as number (%).  \naP-value by chi-square test.  \nbP-value by Fisher’s exact test.","source_license":"public-domain-us","license_restricted":false}