Women who undergo hysterectomy before age 35 may face significantly higher long-term heart risks, even if their ovaries are preserved, a study found Wednesday.

The research by experts at Mayo Clinic focused on more than 2,000 US women who had their uterus removed but left their ovaries intact -- widely considered the most desirable option if possible because it prevents a woman from entering early menopause.

Compared to women in the same area of Minnesota who did not have hysterectomies, the study found those who did faced a greater risk of obesity, clogged arteries, high blood pressure and high cholesterol in the 20-plus years after surgery.

The elevated risks ranged from 13 percent more for high blood pressure to 33 percent more for coronary artery disease.

For women under age 35, the risks were particularly acute -- a 4.6-fold increased risk of congestive heart failure and a 2.5-fold greater risk of coronary artery disease, when the arteries become hard and narrow, blocking blood flow.

"This is the best data to date that shows women undergoing hysterectomy have a risk of long-term disease -- even when both ovaries are conserved," said lead author Shannon Laughlin-Tommaso, an obstetrician-gynecologist at Mayo Clinic.

"Hysterectomy is the second most common gynecologic surgery, and most are done for benign reasons, because most physicians believe that this surgery has minimal long-term risks," she added.

- 'Consider alternatives' -

Some 400,000 operations to remove the uterus, or womb, are performed each year in the United States.

Most are not due to life-threatening conditions like cancer, but rather because of painful fibroids, menstrual disorders or uterine prolapse, when the uterus begins to sag into the vagina, according to the study.

In cases of cancer or high genetic risks, doctors may remove the uterus, fallopian tubes and ovaries. In other cases, just the uterus is taken out, rendering a woman unable to become pregnant but preserving her hormonal function through the ovaries, thereby postponing menopause.

This option became more popular after research showed that removing the ovaries along with the uterus can raise the risk of early death and chronic disease.

But experts say the effects of ovary-preserving hysterectomies have not been well studied until now.

"While women are increasingly aware that removing their ovaries poses health risks, this study suggests hysterectomy alone has risks, especially for women who undergo hysterectomy prior to age 35," said Laughlin-Tommaso.

"With the results of this study, we encourage people to consider nonsurgical alternative therapies for fibroids, endometriosis and prolapse, which are leading causes of hysterectomy."

- 'Fascinating' research -

According to obstetrician-gynecologist Jill Rabin, who was not involved in the study, the research is "well-powered" and "fascinating."

While the biological reasons for the health risks are still being studied, researchers suggested that the uterus may play a role in communicating with the hormone-producing ovaries.

Therefore, removing the womb may cut blood flow and change hormonal stimulation to the ovaries, leading to negative effects on the entire body.

"It makes perfect sense if you think about it. It's all connected. Once you disconnect it, it is like cutting a telephone line in a way. You are stopping the communication," said Rabin, who is co-chief of the division of ambulatory care and women's health programs at Northwell Health in New York.

Hysterectomy can also be a life-saving operation, depending on the reason, so women who are considering it should consult closely with their doctors, she added.

"It should be decided with your doctor, spelling out the risks and benefits, so the patient really understands."

Since the study was observational in nature, it stops short of proving cause-and-effect, but raises interesting questions for further research, according to Mitchell Kramer, chairman of the department of obstetrics and gynecology at Huntington Hospital in New York.

In the meantime, any women thinking about the surgery "should consider alternatives to hysterectomy," including treatment with medicines or less invasive procedures, he told AFP in an email.

The study was published in the journal Menopause.