Torsion often occurs with the ovary and tube together (see image above). Around 50% of torsions are associated with a palpable adnexal mass at surgery. If a mass is present, then a dermoid cyst (mature cystic teratoma) is the most common aetiology (3.5–10% of dermoid cysts undergo torsion) (Sorinola et al, 2002).
It is postulated that torsion occurs where there is an unusually long ovarian pedicle with a moderately large cyst. The idea that torsion occurs more frequently in pregnancy is not supported by literature. Once torsion has occurred, there is disruption of venous return, but arterial supply is largely maintained. The risk of recurrent torsion is 10% (Righi et al, 1995). Two percent of torsion involves ovarian malignancies (Sorinola et al, 2002).
Pain due to ovarian torsion is moderate to severe and of sudden onset. In addition to abdominal pain, ovarian torsion is associated with nausea and vomiting. Vaginal bleeding may be present.
Presence of an adnexial mass ≥5 cm in diameter is a risk factor for torsion. Torted ovaries are more likely to be benign than malignant, in pre-menopausal women with the reverse true in postmenopausal women. Ovulation induction is associated with torsion in <10% cases. Women with adnexal torsion may be systemically unwell with peripheral vasoconstriction, tachypnoea, decreased oxygen saturations and evidence of a metabolic acidosis on arterial blood gas analysis.