High prevalence of small intestinal bacterial overgrowth and intestinal methanogen overgrowth in endometriosis patients: A case-control study

Halfon P, Philippe Halfon, Estrade JP, Jean-Louis Estrade, Jean-Philippe Estrade, Jean‐Philippe Estrade, Guillaume Pénaranda, Choucroun N, Nathalie Choucroun, Jérôme Bouaziz, Bouaziz J, Alba Nicolas-Boluda, Alba Nicolas‐Boluda, Alba Nicolás‐Boluda, Nicolas-Boluda A, F. Rétornaz, Frédérique Retornaz, Retornaz F, Brice Gurriet, Gurriet B, Anne Plauzolles
International Journal of Gynecology & Obstetrics · 2025 · vol. 170(1) , pp. 284–291 · doi:10.1002/ijgo.70005 · PMID:39959963 · W4407618504
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This case-control study found a significantly higher prevalence of small intestinal bacterial overgrowth and intestinal methanogen overgrowth in endometriosis patients compared to controls.

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This case-control study investigated the prevalence of small intestinal bacterial overgrowth (SIBO) and intestinal methanogen overgrowth (IMO) in women with endometriosis compared to age-matched controls. The researchers analyzed lactulose breath test results from 148 endometriosis patients and found significantly higher rates of SIBO/IMO, altered transit times, constipation, and dizziness in the affected group. Methane overgrowth was particularly prevalent among positive cases, with specific gas types linked to distinct gastrointestinal symptoms such as diarrhea or acid reflux. This paper is centrally about endometriosis — specifically examining the high comorbidity of gut microbiome disturbances within this patient population.

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Abstract

OBJECTIVE: The purpose of this study is to raise awareness of small intestinal bacterial overgrowth (SIBO) and intestinal methanogen overgrowth (IMO) prevalence among patients with endometriosis to improve global recommendations in the standard of care for endometriosis. METHODS: This case-control study included a cohort of 1027 women who underwent the lactulose breath test (LBT) during their healthcare check-up to diagnose SIBO and/or IMO from November 2021 to June 2023. One hundred and forty-eight endometriosis patients were selected based on magnetic resonance imaging or a histological assessment. Each were matched with an equal number of women without endometriosis based on the exact age. RESULTS: SIBO/IMO prevalence was significantly higher among women with endometriosis, with up to 136 out of 148 who tested positive, 91.9% (95% confidence interval [CI] 86.3-95.7%) against 123 in the control group, 83.1% [76.1-88.8%], P = 0.0223. Women with endometriosis showed a significantly higher incidence of altered transit than those without (85.8 vs. 71%, P = 0.0019) and an increased prevalence of constipation (67.8 vs. 44.7%, P = 0.0017) and dizziness (44.8 vs. 28.7%, P = 0.0245). Overall, methane overgrowth accounted for up to 63.2% in women with endometriosis who tested positive for methane overgrowth. SIBO H2 was associated with a higher risk of developing diarrhea (P = 0.0027), whereas those positive for IMO were at a higher risk of developing acid reflux (P = 0.0132). CONCLUSION: Abnormal digestive overgrowth should be assessed in all endometriosis cases, as this approach could offer a new therapeutic strategy.
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Abstract

Objective The purpose of this study is to raise awareness of small intestinal bacterial overgrowth (SIBO) and intestinal methanogen overgrowth (IMO) prevalence among patients with endometriosis to improve global recommendations in the standard of care for endometriosis.

Methods

This case–control study included a cohort of 1027 women who underwent the lactulose breath test (LBT) during their healthcare check-up to diagnose SIBO and/or IMO from November 2021 to June 2023. One hundred and forty-eight endometriosis patients were selected based on magnetic resonance imaging or a histological assessment. Each were matched with an equal number of women without endometriosis based on the exact age.

Results

SIBO/IMO prevalence was significantly higher among women with endometriosis, with up to 136 out of 148 who tested positive, 91.9% (95% confidence interval [CI] 86.3–95.7%) against 123 in the control group, 83.1% [76.1–88.8%], P = 0.0223. Women with endometriosis showed a significantly higher incidence of altered transit than those without (85.8 vs. 71%, P = 0.0019) and an increased prevalence of constipation (67.8 vs. 44.7%, P = 0.0017) and dizziness (44.8 vs. 28.7%, P = 0.0245). Overall, methane overgrowth accounted for up to 63.2% in women with endometriosis who tested positive for methane overgrowth. SIBO H2 was associated with a higher risk of developing diarrhea (P = 0.0027), whereas those positive for IMO were at a higher risk of developing acid reflux (P = 0.0132).

Conclusion

Abnormal digestive overgrowth should be assessed in all endometriosis cases, as this approach could offer a new therapeutic strategy. CONFLICT OF INTEREST STATEMENT The authors report no conflicts of interest. DATA AVAILABILITY STATEMENT All fully anonymized individual participant data that underlie the results reported in this article will be made available.

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Condition tags

endometriosis

MeSH descriptors

Blind Loop Syndrome Blind Loop Syndrome Blind Loop Syndrome Blind Loop Syndrome Blind Loop Syndrome Blind Loop Syndrome Blind Loop Syndrome Blind Loop Syndrome Blind Loop Syndrome Blind Loop Syndrome Blind Loop Syndrome Blind Loop Syndrome Blind Loop Syndrome Blind Loop Syndrome Blind Loop Syndrome Blind Loop Syndrome Blind Loop Syndrome Blind Loop Syndrome Blind Loop Syndrome Blind Loop Syndrome

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