Background and Objectives: Endometriosis is a chronic, estrogen-dependent inflammatory disease with multifactorial pathogenesis. Increasing evidence suggests that alterations in the gut and reproductive tract microbiota may contribute to disease development, progression, and associated symptoms through immune, hormonal, and metabolic mechanisms. This systematic review aimed to synthesize current human evidence on microbiota composition and function in women with endometriosis. Materials and Methods: A systematic literature search was conducted according to PRISMA 2020 guidelines across PubMed, Embase, Web of Science, Scopus, and the Cochrane Library. Observational human studies published in English between January 2015 and September 2025 evaluating gut, vaginal, cervical, endometrial, or peritoneal microbiota in women with endometriosis were included. Two reviewers independently screened studies, extracted data, and performed a qualitative synthesis due to methodological heterogeneity. Results: Nineteen studies were included, encompassing gut and reproductive tract samples analyzed primarily by 16S rRNA sequencing. Across cohorts, endometriosis was consistently associated with microbial dysbiosis characterized by enrichment of Proteobacteria and Firmicutes and depletion of Bacteroidetes, Lactobacillus, and Bifidobacterium. Increased abundance of opportunistic taxa, particularly Escherichia coli, Streptococcus, and Klebsiella, was frequently reported. Functionally, dysbiosis was linked to increased β glucuronidase activity, enhanced estrogen enterohepatic recirculation, reduced short-chain fatty acid production, and activation of pro-inflammatory immune pathways. Several studies reported correlations between microbial profiles, disease stage, pelvic pain, and infertility. Conclusions: Current evidence supports a reproducible association between gut microbiota dysbiosis and endometriosis. Altered microbial composition and function may contribute to chronic inflammation, hormonal imbalance, and disease persistence. Longitudinal and multi-omic studies are needed to clarify causality and to evaluate microbiota-based diagnostic and therapeutic strategies.

Intraovarian platelet-rich plasma (PRP) has been proposed as an experimental treatment for women with diminished ovarian reserve and poor ovarian response, but the optimal route of administration remains unclear. This study compared laparoscopic and transvaginal ultrasound-guided PRP administration and investigated whether the route of injection was independently associated with ovarian response and reproductive outcomes. This retrospective multicenter study included 119 women undergoing intraovarian PRP at two Italian fertility centers: 50 received laparoscopic PRP and 69 underwent transvaginal ultrasound-guided administration. In both groups, 3 mL of PRP was injected into each ovary. Post-treatment ovarian response was available for 79 women. Primary outcomes were the numbers of retrieved and mature (MII) oocytes. Secondary outcomes included embryo yield, pregnancy outcomes, and longitudinal changes in ovarian reserve markers. Multivariable linear regression was used to adjust for baseline anti-Müllerian hormone (AMH), antral follicle count (AFC), and double ovarian stimulation (DUO-STIM). Retrieved oocytes were 4.64 ± 3.61 after laparoscopic versus 3.45 ± 3.86 after transvaginal administration (p = 0.06), while MII oocytes were 3.38 ± 2.84 versus 2.83 ± 3.04 (p = 0.25). After adjustment for AMH, AFC, and DUO-STIM, the route of administration was not independently associated with retrieved (β −0.78; 95% CI −2.49 to 0.92; p = 0.37) or mature oocytes (β −0.23; 95% CI −1.56 to 1.11; p = 0.74). DUO-STIM was positively associated with both outcomes. In the transvaginal cohort, a modest early increase in AMH was not sustained over subsequent follow-up. Pregnancy analyses were exploratory because of the limited number of embryo transfers. The route of intraovarian PRP administration was not independently associated with ovarian response after accounting for baseline ovarian reserve and stimulation strategy. These findings do not demonstrate an advantage of laparoscopic administration and support further prospective evaluation of the less invasive transvaginal approach using standardized PRP and stimulation protocols.