Clinical risk factors for ovarian torsion.

Ovarian torsion is a relatively common gynaecological emergency, usually presenting as acute lower abdominal pain. The underlying pathophysiology involves torsion of the ovarian tissue on its pedicle leading to reduced venous return, stromal oedema, internal haemorrhage and infarction with the subsequent sequelae. It is not clear from looking at the literature which factors are responsible for the development of ovarian torsion and what are the odds of a particular clinical feature in determining the likelihood of developing ovarian torsion. In order to assess the likelihood of a particular clinical feature to be a risk factor for ovarian torsion, we studied the prevalence of each presenting clinical feature in the background population of women, for instance, looking at ovarian cysts and compared this with the odds of the feature occurring in the affected population of torsion patients. Thus we compared the odds of various clinical variables in ovarian torsion patients against the odds of the same feature occurring in the background population of women. Ovarian cysts are three times more common in ovarian torsion cohorts than in the general population. Evidence suggests that ovarian cysts are very common in the asymptomatic pregnant cohorts; however, they spontaneously resolve as the pregnancy progresses. Pregnancy is a risk factor for torsion (odds ratio: 18:1); however, it remains an uncommon event (0.167%). Tubal sterilisation practices vary according to geographical location and over chronology of the published literature. After considering the extremes of variation in tubal sterilisation practices, the risk of torsion increases by at least 8-fold following surgery. Hysterectomy with ovarian conservation is not a risk factor of torsion.