An ovarian torsion (also sometimes termed under adnexal torsion) refers to rotation of the ovary and portion of the fallopian tube upon the supplying vascular pedicle (also termed tubo-ovarian torsion). This can be intermittent or maintained and results in venous, arterial and lymphatic stasis. It is a gynaecologcial emergency and requires urgent surgical intervention to prevent ovarian necrosis.
Ovarian torsion has a bimodal age distribution occurring mainly in young women (~ 15 - 30 years) and in post-menopausal women. Approximately 20% of the cases occur during pregnancy. 1
Torsion occurs for two main reasons: 2
- hypermobility of the ovary ~ 50%
- adnexal lesion ~ 50-80%
Most patients present with severe lower abdominal and pelvic pain, nausea, and vomiting. A raised white cell count is common.
The end-result of ovarian torsion is haemorrhagic infarction and necrosis. This can occur within hours of torsion onset.
Torsion of a normal ovary more commonly occurs in young children when developmental abnormalities may be implicated in the pathogenesis, such as excessively long fallopian tubes or an absent mesosalpinx. In adulthood causes include both benign and malignant ovarian tumours, polycystic ovaries and adhesions. In early pregnancy a torsion can occur secondary to a corpus luteum cyst or laxity of the adjacent tissues.
The main feature of torsion is ovarian enlargement due to venous / lymphatic engorgement, oedema and haemorrhage. Secondary signs include free pelvic fluid, an underlying ovarian lesion, reduced or absent vascularity and a twisted dilated tubular structure corresponding to the vascular pedicle. Adnexal torsion is generally unilateral, with a slight (3:2) right-sided predilection (presumably due effects of the sigmoid colon being on the left) 6,8.
Ultrasound is the imaging modality of choice. Sonographic features include
- enlarged hypo or hyperechoic ovary
- peripherally displaced follicles
- Doppler 3
- little or no intra-ovarian venous flow (common)
- absent arterial flow (less common)
- absent or reversed diastolic flow
- normal vascularity does not exclude intermittent torsion
- normal Doppler flow can also occasionally be found due to dual supply from both the ovarian and uterine arteries
- free pelvic fluid : may be seen in > 80% of cases 10.
- whirlpool sign of twisted vascular pedicle 3
- underlying ovarian lesion can often be found
- the uterus may be slightly deviated towards the torted ovary.
- good at ruling out ovarian torsion if a normal ovary / adnexa is seen
- torsion appears as a complex adnexal lesion representing:
- enlarged ovary
- distended pedicle
- possible underlying ovarian lesion
- HU > 50 on non-contrast CT suggests haemorrhagic necrosis 2
- lack of enhancement may be seen
- surrounding fat stranding oedema and free fluid
Usually not the imaging modality of choice as urgent imaging is required.
If haemorrhagic infarction is present signal changes include 4
- thin rim of high signal (methaemaglobin) without contrast enhancemen
- endometriomas and haemorrhagic corpus luteal cysts are less likely to have high T1 rim and do not usually involve the entire ovary
- T2 - can have low signal due to interstitial haemorrhage
Treatment and prognosis
Urgent surgery is required to prevent ovarian necrosis. Most ovaries are not salvageable in which case a salpinogo-oophorectomy is required. If not removed the necrotic ovary can become infected and cause abscess or peritonitis. In the case of a non-infarcted adnexa, surgical untwisting can be performed. Mortality resulting from ovarian torsion is rare. Spontaneous de-torsion has also been reported.
For an enlarged oedematous ovary +/- Fallopian tube, consider
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- 2. Dähnert W. Radiology Review Manual. Hubsta Ltd. (2007) ISBN:0781766206. Read it at Google Books - Find it at Amazon
- 3. Lee EJ, Kwon HC, Joo HJ et-al. Diagnosis of ovarian torsion with color Doppler sonography: depiction of twisted vascular pedicle. J Ultrasound Med. 1998;17 (2): 83-9. J Ultrasound Med (abstract) - Pubmed citation
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- 6. Rha SE, Byun JY, Jung SE et-al. CT and MR imaging features of adnexal torsion. Radiographics. 22 (2): 283-94. Radiographics (full text) - Pubmed citation
- 7. Hiller N, Appelbaum L, Simanovsky N et-al. CT features of adnexal torsion. AJR Am J Roentgenol. 2007;189 (1): 124-9. doi:10.2214/AJR.06.0073 - Pubmed citation
- 8. Chiou SY, Lev-toaff AS, Masuda E et-al. Adnexal torsion: new clinical and imaging observations by sonography, computed tomography, and magnetic resonance imaging. J Ultrasound Med. 2007;26 (10): 1289-301. J Ultrasound Med (full text) - Pubmed citation
- 9. Warner MA, Fleischer AC, Edell SL et-al. Uterine adnexal torsion: sonographic findings. Radiology. 1985;154 (3): 773-5. Radiology (abstract) - Pubmed citation
- 10. Eurorad teaching files : Case 7979
Synonyms & Alternative Spellings
|Synonyms or Alternative Spelling||Include in Listings?|
|Torsion of the ovary||✗|
|Torsion of ovary||✗|
|Torsion of the ovaries||✗|
|Torsion of ovaries||✗|