An observational study in Fertility, Infertility and Reproductive Health, sponsored by Igenomix. Completed at 1 site in Spain. Open to female participants aged 18 Years to 50 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-04-21.
The goal of this observational study is to evaluate alternative less invasive sampling methods for the analysis of the endometrial microbiome. For that, vaginal swab and endometrial fluid samples will be assessed in comparison with the standard sampling method (an endometrial biopsy), in women aged 18-50 years on an oocyte donation program and/or who attend the clinic for routine gynecological controls, and whose samples will be collected during the secretory phase of a natural menstrual cycle. The study aims to:
Participants will undergo a sampling round (of the 3 sampling methods), and then a second round 1, 2 or 3 months later, as assigned by the investigator.
The endometrium plays a pivotal role in reproductive health, influencing processes such as implantation and pregnancy. Although the endometrium has generally been considered a tissue free of bacteria, numerous studies have documented the presence of an endometrial microbiome mainly composed of different species from the Lactobacillus genus. The presence of pathogenic bacteria has been shown to disrupt the uterine environment, affecting implantation rates and pregnancy success.
Traditional and emerging sampling methods allow for the study of the microbial profile of the endometrium, but the efficiency and representativeness of these techniques vary. Therefore, this study aims to compare the effectiveness, accuracy, and usefulness of three different sampling methods for microbiome analysis: endometrial biopsy, endometrial fluid, and vaginal swab. Additionally, it seeks to compare the endometrial microbial profiles with the vaginal microbiome to assess whether it may provide indirect information about the upper reproductive tract.
Endometrial biopsy is a gynecological procedure routinely performed in the clinical practice to provide the patient with an analysis of their microbiome before embryo transfer, ensuring that it is carried out in a non-pathological endometrium, especially in patients with previous implantation failures. It is considered the standard for uterine lining sampling but is an invasive technique that, due to the discomfort associated with the procedure itself, may not always be feasible. Endometrial fluid is a less invasive method that offers a potential alternative by collecting cells from the endometrial surface. On the other hand, studying the vaginal microbiome, although it may provide insight into reproductive outcomes, may not accurately reflect the microbiome of the uterine cavity, a key location where implantation and pregnancy occur. By using comprehensive microbiome analysis techniques, this study will assess the microbial populations collected by each method and determine the efficiency and usefulness of each sampling technique.
Through direct comparison, this research aims to establish a clearer understanding of how sampling techniques can impact microbiome analysis in the context of reproductive health. The results obtained could have significant implications for clinical practice, potentially offering less invasive and more accurate methods to evaluate the endometrial microbiome. This study aims not only to redirect our approach to sampling the endometrial microbiome but also to improve our understanding of its role in female reproductive health. Furthermore, it would facilitate the assessment of potential correlations between the endometrial and vaginal microbiomes.
2,085 studies on the registry are indexed under Infertility; 357 are open to participants now.
This study's enrollment of 57 is below the median of 200 across 592 observational studies indexed under Infertility.
Browse Infertility studies →Igenomix is the lead sponsor of 31 studies on the registry; 3 are open to participants now.
First submitted after Igenomix became part of Vitrolife.
Counted across the registry records on this site, refreshed daily.
Women, between 18 and 50 years, coming form the donor program and/or patients from the General Gynaecology Unit who attend to routine gynaecological controls to the clinic, and whose samples will be taken during the secretory phase of the natural menstrual cycle.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants in this group will undergo two rounds of samples collection, 1, 2 or 3 months apart, as assigned by the investigator.
Diagnostic Test: Reproductive tract microbiome analysis
Assessment of the endometrial and vaginal microbiome in three different samples: endometrial biopsy (EB), endometrial fluid (EF) and vaginal swab (VS).
Evaluation of minimally invasive techniques for the analysis of the endometrial microbiome
Assessment of the viability and technical reliability of the new sampling techniques (endometrial fluid -EF- and vaginal swab -VS-) to evaluate the endometrial microbiome, compared with the standard sampling technique, the endometrial biopsy - EB-. The endometrial microbiome composition will be determined by DNA extraction and bacterial profiling from the three samples (endometrial biopsy -EB-, endometrial fluid -EF- and vaginal swab -VS-). The EB microbiome will serve as reference and it will be compared with the EF's and VS's microbiome to determine whether they are equivalent.
Time frame: From enrollment to the second sampling round (1 to 3 months, depending on the study assigned group))
Evaluation of the inter-cycle consistency of the microbial profile in a period of 1 to 3 months
Comparison of the endometrial microbiome from each patient at 2 different time points, 1, 2 or 3 months apart. The endometrial microbiome of each patient, determined by DNA extraction and bacterial profiling of the three samples, will be compared at two different time points (1, 2 or 3 months apart) to determine the microbiome's and technique stability and robustness.
Time frame: From enrollment to the second sampling round (1 to 3 months, depending on the study assigned group))
Safety evaluation of the sampling techniques (EB, EF and VS)
Registration of any relevant adverse events related to the techniques reported by participants
Time frame: From enrollment to the end of the study (from 1 to 3 months, depending on the assigned group)
Correlation of the VS's and EF's pH with the microbiome
Determination of the pH in the VS and EF samples and assessment of the possible correlation with the microbial profile.
Time frame: From enrollment to the second sampling round (1 to 3 months, depending on the study assigned group))
Plan to share: No
No publications or documents are linked to this record.
Ran from Jun 2025 to primary completion in Feb 2026, 8 months.
Of 242 observational studies under Infertility, half reached primary completion within 39 months of starting (the median), counting those still running; a quarter within 16 and three quarters within 100. This study's 8 months is below that.
How these figures are worked out, and which studies are left out of them.
This study is completed, as verified in Apr 2026. You cannot join it, but the record below documents what was studied.
Get an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.
Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.