A wide differential diagnosis should be kept in mind, and tests should be tailored both to rule out other diagnoses and to rule in the diagnosis of ovarian torsion.
Explore This IssueACEP News: Vol 30 – No 11 – November 2011
The differential diagnosis often consists of the following:
- Hemorrhagic/ruptured ovarian cyst
- Ectopic pregnancy
- Pelvic inflammatory disease
- Renal colic
- Bowel obstruction
A comprehensive approach must be taken to diagnose ovarian torsion. Laboratory tests will not diagnose ovarian torsion but will augment the clinical evaluation of a young female presenting with abdominal pain. Urinalysis, serum HCG, and complete blood count are all useful tests for evaluating other causes of acute abdominal pain.
Pelvic ultrasound is the primary imaging modality in suspected ovarian torsion in children and peripubertal adolescents. In patients whose clinical presentation does not dictate immediate surgical intervention, ultrasound should be performed expeditiously. As young children and some adolescents cannot undergo transvaginal ultrasound, it is important for the patient to have a full bladder to maximize the chance of visualizing the ovaries on a transabdominal ultrasound.The most common abnormal finding on ultrasound is an enlarged, heterogeneous-appearing ovary. Other studies have suggested that enlarged ovaries that cross the midline are associated with adnexal torsion.
However, because up to 34% of cases of torsion have normal sonographic appearance of the ovaries, pelvic ultrasound can play an important role in guiding the management of ovarian torsion and should be used as an adjunct to the history and physical examination. The addition of color Doppler ultrasound has not been found to improve diagnostic accuracy. It should be noted that the presence of blood flow on Doppler ultrasound does not rule out ovarian torsion. One pediatric study found that 64% of known ovarian torsions had blood flow on color Doppler.16-22
MRI and CT can also reliably detect ovarian lesions and have been recommended as adjunctive diagnostic modalities. One case study found MRI to be helpful in diagnosing early ovarian torsion by identifying a twisted pedicle that was missed on ultrasound.23 When transabdominal pelvic ultrasound is unable to define a diagnosis, MRI may reveal a predominantly hyperintense signal containing small areas with hypointense lesions in T2-weighted images, a potential sign of hemorrhagic infarction.17 However, the accuracy of MRI and CT varies in the literature and has yet to be validated. In general, abnormal ovarian size or masses may be detected by either modality. MRI and CT have not been found to provide any significant advantage when combined with ultrasound versus ultrasound alone, and may delay necessary surgical intervention.