Hysterectomy is one of the most commonly performed surgeries in women. Approximately 600,000 hysterectomies are performed each year in the United States, second only to cesarean sections.

According to the Centers for Disease Control and Prevention (CDC), 11.7 percent of women between the ages of 40-44 had a hysterectomy from 2006-2010. By the age of 60, more than one-third of all women have had a hysterectomy.

Although surgeons may suggest removing the ovaries to prevent possible ovarian cancer, this is not always medically necessary and may contribute to increased risk of cardiovascular disease, other cancers and higher overall mortality, according to recent research. A study in the British Medical Journal compared cases in which both ovaries were removed with those in which some ovarian tissue was conserved.

The study, led by Richard Lilford, professor of obstetrics and gynecology and chair in public health at the University of Warwick's Warwick Medical School, examined a national database of hospital admissions and linked them to the national register of deaths. Unlike the previous, smaller Nurses' Health Study, the study was conducted on a countrywide basis rather than in a sample and examined associations between operation type and subsequent hospital admissions, as well as mortality.

More than 113,679 hysterectomy cases were studied; the ovaries were removed in a third of these. The women were between the age of 35 and 45 (mean age, 41 years), the upper limit ensuring that the great majority of cases would be premenopausal. Women with a history of reproductive cancer, including breast cancer, were excluded. Outcomes included mortality, mortality resulting from ischemic heart disease and hospital admission for ischemic heart disease, cancer (all cancers, ovarian cancer, breast cancer), and suicide.

Patients in the ovarian conservation group were less likely to be admitted for ischemic heart disease after hysterectomy than were those in the bilateral removal group. They were also less likely to have a cancer related post-hysterectomy admission.

Fewer women who retained one or both ovaries compared to those who had both removed died within the study period (0.6 percent compared to 1.01 percent). Mortality was lower when ovarian tissue was conserved than when all ovarian tissue was removed, with a statistically significant difference of 0.41 percentage points. This amounts to one death in about 240 operations over 10 years, which is clinically significant.

Researchers also found that there was a slow decline in the number of hysterectomies performed. Nearly 9,000 women had a hysterectomy for a benign condition in the target age range in 2014 compared to almost 13,000 in the 2004-05 group.

Many premenopausal women with no specific risk factors have both ovaries removed during hysterectomy to protect them from the possible development of ovarian cancer. However, removing the ovaries may have long-term harmful effects that should be weighed against the potential benefit. A decrease in endogenous estrogen may increase the risk of cardiovascular disease or all cause mortality, but little empirical evidence for this exists.