Ovary-sparing hysterectomy may not offer protection against metabolic syndrome

Having a hysterectomy, even if the ovaries are spared, may place women at greater risk for a constellation of cardiovascular risk factors known as metabolic syndrome, new research shows.

The findings, presented last month at the American Heart Association's Scientific Sessions conference in Philadelphia, call into question the long-held belief that ovary-sparing hysterectomies could protect a woman from heart-related risks associated with removing the uterus. The research is considered preliminary until full findings are published in a peer-reviewed journal.

"Women who get hysterectomies may not realize they are at cardiovascular risk," said senior researcher and cardiologist Dr. Erin Michos, director of women's cardiovascular health research and an associate professor of medicine at Johns Hopkins School of Medicine in Baltimore. "They might need more attention getting their heart health checked out, even if the ovaries are preserved."

An estimated 20 million women in the U.S. have had surgery to remove the uterus, a procedure known as a hysterectomy. It is the leading gynecological procedure in the nation and is done to treat a variety of conditions, such as ovarian, uterine or cervical cancer, fibroids, endometriosis, or heavy vaginal bleeding. Prior research has linked early menopause, brought on by a hysterectomy, to a higher risk for cardiovascular disease, especially strokes.

In an effort to prevent that added risk, the uterus may be removed but not the ovaries, which can then continue to produce estrogen and other hormones. Preserving the ovaries if a hysterectomy is performed during childbearing years had been thought to offer some protection from cardiovascular disease by delaying menopause. But a growing body of research casts doubt on that premise.

For example, a 2018 study in Menopause found women 35 or younger who had ovary-sparing hysterectomies nonetheless faced a 4.6-fold increased risk for heart failure and a 2.5-fold increased risk for heart disease. But there is little data about the relationship between ovary-sparing hysterectomies and metabolic syndrome, a cluster of conditions that raises a person's risk for heart disease and stroke. These include large waist circumference, high blood pressure, high blood glucose, high triglycerides and low "good" HDL cholesterol. Metabolic syndrome is diagnosed when someone has at least three of those.

In the new study, researchers looked at an ethnically diverse group of women from six locations across the U.S.—Baltimore; Chicago; Forsyth County, North Carolina; Los Angeles; St. Paul, Minnesota; and New York City. Just over half of the 3,367 women, who were an average 59 years old, said they either had the uterus or ovaries removed, or both. Over 10 years of follow-up, researchers compared the women's risk for developing metabolic syndrome to that of women who had not had their uterus or ovaries removed.

Overall, women who had their uterus, ovaries or both removed were more likely to develop metabolic syndrome than those without such histories. Women who had only the uterus removed faced a 52% greater risk, compared to a 38% greater risk for women who had both the uterus and ovaries removed.

Women who developed metabolic syndrome were older, more likely to be overweight, less physically active, more likely to have given birth to three or more children and more likely to be menopausal than those who did not develop metabolic syndrome. Those who had been on hormone therapy were less likely to develop metabolic syndrome.

"There is a perception that ovary-sparing hysterectomies are safer for women's cardiovascular health," said cardiologist Dr. Laxmi Mehta, who holds the Sarah Ross Soter endowed chair for women's cardiovascular health research at The Ohio State University Wexner Medical Center in Columbus. "Patients are told, 'We'll spare your ovaries to protect your heart.' But this study suggests that the idea that ovarian preservation is helping is not true.

"Decisions are being made about a woman's body, and we need to make sure we have the right data to make those decisions," said Mehta, who was not involved in the research.

Why ovary-sparing hysterectomies may be contributing to cardiovascular risk remains unclear. Michos said it could be that having a hysterectomy reduces blood flow to the ovaries, which can cause problems with their function.

"It is also possible that it is not the isolated surgical procedure that predisposes a woman to the higher risk for metabolic syndrome," said lead researcher Dr. Eric Broni, a postdoctoral fellow in the division of maternal fetal medicine at the University of Pennsylvania in Philadelphia. Rather, he said, it could be that a woman already had risk factors for metabolic syndrome that simply weren't showing signs or causing symptoms yet. "Probably, these risk factors were unmasked and aggravated by the surgical procedure."

Whatever the reason, the findings suggest women who need hysterectomies should carefully consider their options and pay close attention to heart health risk factors, Mehta said.

"Regardless of the type of hysterectomy a woman has, she needs to stay on top of her cardiovascular risk factors prior to her surgery, after her surgery and for the rest of her lifetime," she said.

"Whether it's causal or as a result of shared risk factors, there is a link. These women should have a good cardiovascular screening, including having blood pressure, blood glucose and lipids checked, along with following a healthy lifestyle," Mehta said.