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Mr Parijat Bhattacharjee, Private Consultant Gynaecologist, Harrow, Brentford, Northwood, London, UK / Media / Videos » Bjog 2019 Microbiome Endometriosis

Bjog 2019 Microbiome Endometriosis

Bjog 2019 Microbiome Endometriosis
Posted on: 03-Jul-2026

This video, titled "Bjog 2019 Microbiome Endometriosis" by Gynae Consultant, reviews a 2019 systemic research paper published in the British Journal of Obstetrics and Gynaecology (BJOG). Conducted by George Condous and his team from Sydney, Australia, the study investigates the relationship between the human microbiome (microorganisms and their genes) and endometriosis.

Background and Immune Dysfunction Theory

  • The Microbiome Horizon: While the gut microbiome has been heavily studied over the last two decades, research regarding the female genital tract microbiome and its impact on gynecological conditions remains scarce.
  • Endometriosis Etiology: While Sampson's theory of retrograde menstruation is the primary explanation for endometriosis, other theories exist (such as coelomic metaplasia, embryonic rests, and stem cell involvement).
  • Immune System Link: Endometriosis is an inflammatory condition characterized by altered levels of pro-inflammatory cytokines, autoantibodies, peritoneal macrophages, and B cells, alongside a decrease in T cells and natural killer cells. The review examines how the microbiome may modulate the immune system, leading to immune dysfunction where the body fails to properly regulate inflammation.

Overview of the Systematic Review

The team evaluated papers published between 2002 and 2019:

  • Out of 251 identified studies, only 18 relevant papers met the criteria for the systematic review.
  • Animal Studies (5 total): Four were conducted on mice (which do not naturally menstruate and required surgical endometrial implantation) and one on rhesus monkeys.
  • Human Studies (13 total): Twelve of these studies involved patients with laparoscopically confirmed endometriosis. Tissue and fluid samples were analyzed from various regions, including the gut, peritoneum, ovaries, fallopian tubes, endometrium, vagina, and cervix.

Key Clinical Findings

1. Bacterial Variations

Out of the 18 studies, 12 showed statistically significant differences in the microbiome of individuals with endometriosis compared to healthy controls:

  • Increased Bacteria: Proteobacteria, Enterobacter, E. coli, and Streptococcus were significantly elevated in women with endometriosis.
  • Decreased Bacteria: Protective Lactobacilli species were notably reduced.
  • Inconclusive Data: Variations in Firmicutes and Gardnerella species were associated with endometriosis, but conflicting data across studies left their exact role unclear.

2. Viral Associations (The Virome)

Four studies specifically evaluated viruses, finding that Human Papillomavirus (HPV) was significantly increased in women suffering from endometriosis.

3. Geographical and Ethnic Variations

The review highlighted that geographic location, culture, and diet influence the microbiome. Data indicated that Black women showed a lower incidence of endometriosis and its associated microbiome shifts compared to Asian women.

Future Diagnostic and Treatment Potential

The video explores how these microbiome insights could revolutionize clinical care:

  • Non-Invasive Screening: Research showing elevated E. coli in menstrual blood could pave the way for early, non-invasive diagnostic screening tools.
  • Antibiotic Interventions: In mouse models, the antibiotic metronidazole was shown to significantly decrease ectopic endometrial lesions and localized inflammation.
  • The "Estrobolome" Effect: The gut contains specific bacterial species (like Bacteroides, Bifidobacterium, Escherichia, and Lactobacillus) that produce enzymes like beta-glucuronidase. These enzymes deconjugate bound estrogen, releasing free estrogen back into circulation. Elevated circulating estrogen can drive and sustain endometriosis, pointing to the gut-estrogen axis as a prime target for future therapeutic treatments.