Hysterectomy is a common treatment for many conditions, including fibroids and excessive bleeding but younger women need to be made aware that this is a potential risk of the surgery that can have long-term health consequences.

Many obstetricians and gynaecologists have long linked the two events, as even the most careful hysterectomy can leave a woman with non-functioning ovaries within a few years, if they are left at all.

What’s the evidence?

A study by Duke University researchers in the USA was the largest analysis to track over time the actual hormonal impact of woman who had hysterectomies and compare them to women who had not.

The study involved nearly 900 women ages 30 to 47 at two hospitals and was followed up with blood tests and questionnaires for five years. Half the women (the control group) had no surgery, while the remainder women underwent hysterectomies that spared at least one ovary.

Preserving the ovaries while removing the uterus is a strategy designed to allow a woman’s hormone production to continue, which has health benefits, but doctors have long known that early menopause — either from surgery or from other factors that halt egg production — can increase a woman’s risk of osteoporosis, heart disease, and other ailments.

However, despite preserving the ovaries, the Duke team found that 14.8 percent of women in the study who had hysterectomies experienced menopause over the course of the study, compared to 8 percent of women who had no surgery.

The risk for early menopause was highest among women who had one ovary removed along with their uterus, but it remained elevated even when both ovaries stayed in place. The Duke team’s analysis estimated that menopause occurred approximately two years earlier in the women who underwent hysterectomy.

Although it is not known exactly what triggers the ovaries of some women to shut down after a hysterectomy there are several theories. Women often mistakenly believe if they have one ovary remaining that it will continue to function long-term, but this is not often the case.

One theory as to why they stop functioning is that surgery disrupts the blood flow to the ovaries. This means that the surgery leads to early ovarian failure. Another theory is that it’s not the surgery, but the underlying condition preceding the surgery that causes it.

Regardless of the cause, this finding provides women and their doctors with concrete information about a potential risk for future health problems.

Patricia G. Moorman, PhD, MSPH, lead author of the study, commented that “This could potentially change practice because women who are considering hysterectomy for fibroids or other problems may want to explore other treatment options for their condition if they know they may go through menopause earlier.”