Excerpt from Ovarian Torsion

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Background

Adnexal torsion requires a quick and confident diagnosis to save the adnexal structures from infarction. Typically, the ovary and fallopian tube are involved. This condition usually is associated with reduced venous return from the ovary as a result of stromal edema, hyperstimulation, or a mass. Ultrasonography with color Doppler analysis is the method of choice for the evaluation of adnexal torsion because it can show morphologic and physiologic changes in the ovary. Gray-scale and spectral findings are correlated with the age of the torsion (ie, acute torsion vs chronic torsion) and the degree of the twist or torsion.

Pathophysiology

Adnexal torsion may occur without a definitive etiology. It often occurs as a result of increased weight of the ovary, whether due to reduced venous return from the ovary of unknown cause or an actual ovarian and/or adnexal mass with torsion of the ovary or ovary and fallopian tube. The torsion itself further reduces venous return from the ovary. Greater degrees of adnexal torsion reduce arterial flow within the ovary, although flow within the vascular pedicle usually continues. Hemorrhagic infarction within the ovary may occur when the torsion is persistent or chronic.

Frequency

United States

Adnexal torsion accounts for an estimated 3% of surgical gynecologic emergencies. Approximately 50-60% of cases of torsion are associated with an adnexal mass.

Mortality/Morbidity

• Mortality from torsion is rare. Cases in which pulmonary emboli result from thrombi in the pelvic veins have been reported in patients with ovarian torsion, adnexal torsion, or both.
• Morbidity usually arises from the pain associated with torsion. The adnexa may become gangrenous with chronic torsion.

Age

In women, 2 groups tend to be affected: (1) women in their mid 20s and (2) women who are postmenopausal. Note that approximately 20% of the cases of torsion occur during pregnancy. Women with an adnexal mass who are postmenopausal also may be affected. Adolescents, perhaps because of changes in the weight of their maturing adnexa, also are at risk.

Anatomy

The ovary has a dual arterial and venous blood supply. The arterial supply is derived both from the ovarian arteries that branch from the abdominal aorta and from the adnexal branches of the uterine artery. The venous system parallels the arterial, with the exception that the left ovarian vein empties into the left renal vein, whereas the right ovarian vein courses into the inferior vena cava. The fallopian tubes are fed and are drained by means of vessels that anastomose with ovarian branches derived from uterine vessels in the mesosalpinx.

Clinical Details

Confident and early diagnosis of adnexal torsion is imperative. Color Doppler sonography has a vital role in the examination of women with lower abdominal and pelvic pain.

The signs and symptoms associated with torsion are variable and nonspecific. Most patients present with severe lower abdominal and pelvic pain, as well as nausea and vomiting. At clinical examination, appendicitis, gastroenteritis, ectopic pregnancy, pelvic inflammatory disease, and ruptured corpus luteum are considered in the differential diagnosis. Among adolescents, hemorrhagic ovarian cysts must also be considered. Laboratory tests are not helpful because most signs and symptoms of ovarian torsion can be associated with leukocytosis.

Preferred Examination

Perform diagnostic sonography first. Typically, the affected ovary is enlarged with multiple immature or small follicles along its periphery. Color Doppler sonography can help in determining whether the flow is impaired. Rarely, CT or MRI is needed for diagnosis. CT or MRI can serve as a secondary modality when ultrasonographic findings are nondiagnostic.

Limitations of Techniques

Although a lack of intraovarian arterial and venous flow enables confident diagnosis, torsion may be incomplete; this condition may be associated with adnexal flow, as depicted with color Doppler sonography. Rarely, the use of improper settings can cause erroneous findings of absent flow. Check that the proper settings are used by looking for flow in the internal iliac vein.

In some cases, flow may be difficult to obtain from the affected ovary, as well as the healthy contralateral ovary. In these cases, the characteristic gray-scale morphologic image of ovarian torsion alone may help in making the diagnosis.

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