Menstrual Effluent Can Change the Future of Endometriosis

Menstrual Effluent Can Change the Future of Endometriosis

Menstrual Effluent, a key player in retrograde menstruation, may uncover the mechanism driving endometriosis progression that has plagued researcher for years.

Key Points


  • Retrograde menstruation, where menstrual effluent (ME) flow into the peritoneal cavity, is cited as a factor that leads to endometriosis. The authors of this study believe that this theory of Retrograde menstruation may support the idea that ME- derived stromal fibroblast cells (SFCs) can serve as a diagnostic tool for endometriosis.
  • The researchers also explored the various possibilities of using ME-derived cells as a tool to better understand the pathobiology of endometriosis and other reproductive disorders.


  • Endometriosis is difficult to diagnose, and delayed diagnosis is associated with increased pain and disease progression, also adversely impact a patient’s quality of life. Thus, there is a need for a noninvasive diagnostic tool that can diagnose the disease quickly.
  • Research has yet to elucidate the mechanisms that drive endometriosis disease progression. 

What’s done here?

  • The participants consisted of reproductive-age women with and without endometriosis. They were not pregnant, not breastfeeding, and not using birth control device. 
  • ME sample collection occurred on days 0, 1, or 2 of the menstrual phase. The participants used a DivaCup to collect the ME for 6-10 hours.
  • The sample was transferred to another container with Normocin™ and penicillin-streptomycin. The samples were then sent to a lab within a 24-hour window.
  • The researchers filtered the cells, washed and used a specific panel of CD45+ or CD45- antibodies, and analyzed by flow cytometer.
  • They also obtained Cultured SFCs, re-suspended and stained with antibody panels and again analyzed using Flow Cytometry.
  • The researchers also collected total cellular RNA after the ME-derived SFCs were isolated. Apart from RNA sequencing, qPCR was used to analyze the ALDH1A1 expression and decidualization related genes.

Key results:

  • There was a significant difference noted between the endometriosis and control group, significantly less uterine natural killer (NK) cells in patients with endometriosis.
  • The ME-derived SFCs of endometriosis group had less decidualization potential. IGFBP-1 production after cAMP stimulation revealed differences in decidualization response.
  • Various genes were differentially expressed in ME-derived SFCs.  
  • The overarching conclusions that can be drawn from this experiment are that menstrual effluent is a useful tool to study the underlying mechanisms of endometriosis, and it is also a non-invasive diagnostic tool.

Limitations of the study:

  • The study population size is small concerning the prevalence of endometriosis worldwide.
  • The functional assays on decidualization capacity used SFCs from participants who were not using hormones. The researchers put forth this restriction because they did not know if hormone use affects decidualization capacity.
  • The researchers did not group and analyze the endometriosis participants with regards to disease severity.
  • The control participants, participants without endometriosis, in the study were not laparoscopically confirmed.

Lay Summary

During Endometriosis Awareness Month, Warren et al. published a paper entitled “Analysis of menstrual effluent: diagnostic potential for endometriosis” in Molecular Medicine. This paper relies heavily on the theory of retrograde menstruation, where menstrual effluent flows into the peritoneal cavity.

It is thought that retrograde menstruation is a factor that eventually leads to endometriosis. The authors of this study wanted to examine the diagnostic potential of ME-derived stromal fibroblast cells (SFCs). They also looked towards ME-derived cells as a tool to study the pathobiology of endometriosis and other reproductive disorders.

The study consists of a multitude of experiments. The researchers recruited reproductive-age patients with and without endometriosis to collect their menstrual effluent on the first, second, or third day of their menstrual cycle. The effluent was examined using flow cytometry for two specific cell populations (namely the CD45- and CD45+). SFCs were also isolated. These analyses were supposed to identify markers of decidualization and differentially expressed genes in the menstrual stromal fibroblasts.

The results showed one significant difference within the CD45+ and CD45- cell populations. There were less uterine Natural Killer (NK) cells in the CD45+ portion of ME found in participants with endometriosis. Additionally, SFCs derived from menstrual effluent were found to have lower decidualization potential in women with endometriosis. Many genes differentially expressed by menstrual effluent-derived SFCs originating from the two study populations.

In conclusion, this study proves that menstrual effluent can indeed be used a diagnostic tool for more timely and reliable diagnosis of endometriosis and it also can be used to better understand the pathobiology of the disease. The study funded by the Endometriosis Foundation of America.

Analysis of menstrual effluent: diagnostic potential for endometriosis: Laura A. Warren, Andrew Shih, Susana Marquez Renteira, Tamer Seckin, MD, Brandon Blau, Kim Simpfendorfer, Annette Lee, Christine N. Metz & Peter K. Gregersen


Research Source:

Retrograde menstruation menstrual effluent stromal fibroblast cells flow cytometry qPCR Decidualization potential RNA-Seq RNA Natural Killer Cells


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