The Chance of Getting Pregnant of a Woman with Endometriosis May Soon Be Predictable

Levels of natural killer cells in the uterus may be the key.

Key Points

Highlights:

• Levels of certain cells in the uterus could help predict the likelihood of getting pregnant following endometriosis surgery.

Importance:

• Although more research is needed, these findings could save women with endometriosis and their family a lot of distress.

What's done here:

• Researchers analyzed the blood and endometrium of 58 women who had been surgically diagnosed with endometriosis-associated infertility. 

Key results

• Levels of cells that express a protein called CD34 and that will give rise to different types of blood cells were higher in the endometrium of women with endometriosis who became pregnant compared to those who did not become pregnant (3.97% versus 0.69%)
• Similarly, the expression of another protein called CD56, which is a marker of NK cells was increased in women who became pregnant compared to the who did not (81.1% versus 60.9%).
• There was no difference in the levels of cells that will give rise to NK cells in the blood of women who became pregnant and those who did not.

Limitations of the study:

• More research is needed to confirm the results obtained in this study. 

Lay Summary

Researchers have found a new way of predicting whether or not an embryo will be able to successfully implant into the womb of a woman with endometriosis. These findings could make it possible to predict whether she is likely to become pregnant either naturally or following assisted reproductive treatments.

The predictor in question is the level of so-called natural killer (NK) cells in the uterus. NK cells are types of specialized immune cells that play a crucial role in eliminating cells that are infected by viruses as well as abnormal cells such as cancer cells. NK cells in the uterus also play a critical role in early pregnancy.

The authors of the present study, which was published in the American Journal of Reproductive Immunology had previously shown that NK cell development in the uterus was altered in endometriosis-associated infertility. Now, they wanted to investigate whether this alteration could be used to predict the chance of an embryo implanting into the uterus. 

To test their idea, the researchers analyzed 58 women who all had endometriosis-associated fertility diagnosed with surgery. Around 57 percent of these women (33 out of 58) underwent assisted reproductive treatments such as in vitro fertilization (IVF), intra-cytoplasmic sperm injection (ICSI), or intrauterine insemination (IUI). The researchers looked at the cells that will give rise to NK cells and other types of blood cells in the endometrium (lining of the uterus) and blood of these women. 

They found that the level of certain types of cells that will give rise to different types of blood cells was higher in the endometrium of women who had a positive pregnancy test, or in other words successful implantation compared to women who had unsuccessful implantation. Moreover, these cells had on their surface proteins that are specific to NK cells, meaning that they will turn into NK cells as they mature. Interestingly, when they checked the blood, researchers found no difference in the levels of cells that will give rise to NK cells in women who had successful implantation and those who did not.

“Our study revealed that uterine NK progenitor cell populations are markedly different in patients with endometriosis who proceed to successful or failed embryo implantation,” the researchers wrote. They added that their findings “highlight the fundamental differences” regarding NK cell development in the uterus and the blood, further emphasizing the limitations of focusing on just blood biomarkers when diagnosing endometriosis or following the effect of infertility treatments.

Research Source: https://www.ncbi.nlm.nih.gov/pubmed/29380456