Ovarian torsion

Ovarian torsion is the twisting of an ovary on its ligamentous supports resulting in compromised blood supply. Symptoms are often non-specific although sudden onset of unilateral pelvic pain is common. Nausea and vomiting, peritoneal signs as well as pyrexia can be observed. Up to 60% of cases are missed on the first clinical encounter.

PEDIATRICS: In pediatric patients torsion most likely occurs at menarche; however, it can happen in premenarchal girls and infants. Torsion of a normal ovary is unusual but is more common in adolescents and accounts for approximately 25% of cases.

ADULTS: It is rare to see ovarian torsion from cysts smaller than 5 cm. The most common tumor associated with torsion is a benign mature cystic teratoma. 17%–20% of cases occur in pregnant women. The right ovary is more likely to twist potentially because the space occupied by the sigmoid colon on the left side protects the left ovary.

On ultrasound ovarian enlargement may be seen early in adnexal torsion, even before infarction has occurred. Other findings include free intraperitoneal pelvic fluid and the presence of cystic follicles, with thickening of the cyst wall. It is reported that up to 60% of ovarian torsion has normal color Doppler flow. Doppler flow should not be used to exclude the diagnosis but has utility in determining the viability of the ovary.

CT scans performed on 28 patients with surgically proven ovarian torsion showed an enlarged ovary, an ovarian cyst, or an adnexal mass. In this series, there were no normal CT scans in the group of patients with ovarian torsion. These results strongly suggest that CT findings are unlikely to be normal in a patient who is ultimately diagnosed with ovarian torsion. In addition when US findings are indeterminate, CT might aid in the diagnosis.

Chang, et. al. Pearls and Pitfalls in Diagnosis of Ovarian Torsion. RadioGraphics 2008; 28:1355–1368

Schmitz, Tibbles. Genitourinary Emergencies in the Nonpregnant Woman. Emerg Med Clin N Am 29 (2011) 621–635

Moore, et. al. Prevalence of abnormal CT findings in patients with proven ovarian torsion and a proposed triage schema. Emerg Radiol (2009) 16:115–120

Marin, Alpern. Abdominal Pain in Children. Emergency Medicine Clinics of North America – Volume 29, Issue 2 (May 2011)

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