A study of menstrual effluent showed that there are significant differences between samples taken from patients with endometriosis and healthy controls, indicating that analysis of menstrual blood may have potential as a noninvasive diagnostic test. The research, which was published in Molecular Medicine, was conducted at Feinstein Institute for Medical Research in Manhasset, New York, and may also provide insight into why only 5% to 10% of women develop endometriosis even though retrograde menstruation, which is theorized to be an underlying factor in endometriosis, occurs in almost all women.
The researchers speculated that differences in the cellular biology as well as the genetic makeup of the cells within the effluent could provide a rationale for development of endometriosis in some women but not in others. As part of the Research Out-Smarts Endometriosis (ROSE) program, they collected peripheral and menstrual blood samples from women with endometriosis. Samples from healthy women were taken from the Genotype and Phenotype (GaP) registry. Women who were menstruating, not pregnant or breastfeeding, and who did not have an intrauterine device in place were eligible to participate in the study.
Menstrual effluent was collected on days 0, 1, and 2, of the menstrual phase using a menstrual cup. Seven women were recruited for the endometriosis group and seven for the control group.
The researchers analyzed the effluent for CD45-negative and CD45-positive cell populations using flow cytometry. They also isolated stromal fibroblast cells and analyzed them, after the adding cAMP to stimulate IGFBP-1 production, using decidualization assays. RNA analysis was performed to detect genetic differences between healthy controls and the women with endometriosis.
Only one difference between healthy subjects and women with endometriosis was found on flow cytometry of the CD45-negative and CD45-positve cells: There was a significant decrease in the number of uterine natural killer (NK) cells in endometriosis patients versus controls (P < 0.01) within the CD45-positive fraction of the menstrual effluent. However, there were no differences in granulocytes, monocytes, or T or B cells.
In regard to the stromal fibroblast cells that were cultured, cells from women with endometriosis had impaired decidualization potential when compared with control subjects’ samples: IGFBP-1 levels were lower in cells from women with endometriosis than healthy controls after stimulation of these cells with cAMP.
Numerous genes were also expressed differently in cells of the women with endometriosis versus the controls.
Value of a noninvasive test
Lack of a noninvasive test for endometriosis contributes to delay in diagnosis of the disease, which typically lags by 7 to 10 years after the onset of symptoms. Laparoscopic surgery and histologic confirmation are the gold standards for diagnosis and there are no laboratory diagnostic markers that have been shown to be capable of replacing or enhancing the performance of surgery, the authors stated.
Analysis of menstrual effluent may represent a way toward such a test. “Instead of having to undergo surgery to accurately diagnose endometriosis, these findings will enable us to develop a rapid test for endometriosis based on menstrual blood,” co-author Peter K. Gregersen, MD, said. Larger studies are needed to confirm its diagnostic value, but the ready availability of menstrual effluent and simple collection protocol using a menstrual cup make these studies feasible. In addition, beyond endometriosis, it may turn out that menstrual effluent is useful in diagnosing other reproductive disorders, and can help to improve the understanding of the biology and genetics of endometriosis, ultimately, perhaps, leading to new treatments.