Ovarian torsion is the rotation of the ovary and/or fallopian tube around its vascular pedicle. Constitutes 3% of gynecological emergencies. Begins with venous return obstruction, followed by arterial blood flow interruption leading to ovarian ischemia/necrosis. Early diagnosis and surgical intervention are critical for ovary-sparing treatment (detorsion). Delayed diagnosis requires oophorectomy due to ovarian necrosis. More common in reproductive-age women, with ovarian cyst/tumor as predisposing factor.
Age Range
15-45
Peak Age
25
Gender
Female predominant
Prevalence
Uncommon
In ovarian torsion, the ovary and/or fallopian tube rotates around the vascular pedicle. First, low-pressure venous and lymphatic return is disrupted — causing congestion, edema, and enlargement of the ovary. Increased interstitial pressure also compromises arterial flow, initiating ovarian ischemia. This pathophysiological process directly determines imaging findings: congestion → ovarian enlargement and peripheral follicles (stromal edema pushes follicles peripherally); venous stasis → ovarian parenchymal edema (T2/FLAIR hyperintensity, decreased echogenicity on US); arterial occlusion → diminished/absent flow on Doppler and loss of enhancement on CT/MRI. The whirlpool sign is the direct visualization of the twisted vascular pedicle on Doppler or CT.
Spiral/vortex appearance of the twisted vascular pedicle on color Doppler. Ovarian vessels and fallopian tube rotate multiple times around the pedicle — this rotation appears as intertwined red-blue color mapping (spiral pattern) on color Doppler. Most specific ultrasound finding of ovarian torsion (87-94% specificity). On B-mode, the twisted pedicle may also appear as alternating concentric hyperechoic and hypoechoic rings ('target sign'). Whirlpool sign also helps grade torsion — more rotations around the pedicle indicate higher ischemia risk.
Enlarged ovary (usually >5 cm) with peripherally displaced follicles. Stromal edema pushes follicles to periphery creating 'peripheral follicle sign'. Ovarian stroma appears hypoechoic/edematous.
Report Sentence
The ovary is markedly enlarged (... cm) with peripherally displaced follicular structures; these findings are consistent with ovarian torsion.
Diminished or absent arterial/venous flow in the ovary on Doppler. Venous flow is lost first (low pressure). In advanced stages, arterial flow is also lost. Whirlpool sign — spiral/vortex Doppler signal in the vascular pedicle.
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No arterial/venous flow is detected in the ovary on Doppler examination, consistent with ovarian torsion; whirlpool sign is present.
Spiral/vortex Doppler signal in the twisted vascular pedicle (whirlpool sign). Direct visualization of tubal and ovarian vessels rotating around the pedicle. Most specific US finding of ovarian torsion.
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Whirlpool sign is demonstrated on Doppler examination at the vascular pedicle, confirming ovarian torsion.
Enlarged ovary shows absent or diminished enhancement on contrast-enhanced CT. Ischemic ovary differs markedly from normal contralateral ovary. Twisted pedicle may also demonstrate spiral appearance on CT.
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The left/right ovary is markedly enlarged and shows no enhancement in post-contrast phases; these findings are consistent with ovarian ischemia/torsion.
Marked stromal edema (hyperintensity) in ovary on T2-weighted images. Peripheral follicles show high T2 signal distinguished from edematous stroma. Ovary is generally enlarged with increased signal intensity.
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Hyperintensity consistent with marked edema is seen in the ovarian stroma on T2-weighted sequences, suggesting ovarian torsion/ischemia.
Diffusion restriction in ovarian parenchyma on DWI in advanced-stage torsion. Bright DWI signal in hemorrhagic infarction areas due to cytotoxic edema. This finding indicates necrosis development.
Report Sentence
Diffusion restriction is seen in the ovarian parenchyma on DWI, suggesting development of hemorrhagic infarction.
High attenuation areas (50-70 HU) in the ovary on non-contrast CT — reflecting hemorrhagic infarction. Peripheral follicular structures are low density with increasing conspicuity on contrast.
Report Sentence
High attenuation areas consistent with hemorrhagic infarction are seen in the ovary on non-contrast CT.
Criteria
Rotation of the ovary alone around its own axis. Fallopian tube not involved. Less common.
Distinct Features
Pedicle may be shorter, whirlpool sign seen only in ovarian vessels. More common in pediatric and adolescent age groups.
Criteria
Ovary and fallopian tube rotate together around vascular pedicle. Most common form. Ovarian cyst/tumor is predisposing factor.
Distinct Features
Dilated fallopian tube may accompany. Whirlpool sign includes both ovarian and tubal vessels. Larger pedicle area.
Criteria
Ovary undergoes repeated torsion and spontaneous detorsion. Intermittent pelvic pain episodes. Imaging findings variable.
Distinct Features
Ovary may appear normal during pain-free interval. Doppler flow may be preserved. Enlarged ovary + normal Doppler = intermittent torsion should be considered. Classic findings present during pain episodes.
Distinguishing Feature
Hemorrhagic cyst is usually in normal-sized ovary, reticular/fibrin strand pattern, peripheral vascularity ('ring of fire') preserved on Doppler, no whirlpool sign. Torsion is distinguished by enlarged ovary, peripheral follicles, diminished/absent Doppler flow, and whirlpool sign.
Distinguishing Feature
Tubo-ovarian abscess presents with fever + leukocytosis + elevated inflammatory markers. Thick-walled complex cystic structure, ovary-tube indistinguishable (cogwheel sign), internal debris, increased vascularity. Torsion is distinguished by acute pain + whirlpool + diminished flow.
Distinguishing Feature
Endometrioma has homogeneous hypoechoic internal echoes ('ground glass'), thick capsule, cyclical pain. Doppler flow preserved around wall. Ovarian size usually normal. Torsion is distinguished by acute onset pain, enlarged ovary, peripheral follicles, and diminished Doppler.
Distinguishing Feature
Simple cyst is anechoic, thin-walled, posterior acoustic enhancement, asymptomatic or mild pain. Normal Doppler. Normal ovarian size. Torsion usually develops on a pre-existing cyst — but enlarged ovary, peripheral follicles, and absent Doppler flow are added.
Urgency
emergentManagement
surgicalBiopsy
Not NeededFollow-up
no-follow-upOvarian torsion is an EMERGENCY surgical indication. Early diagnosis (<6-8 hours) offers the possibility of ovary-sparing laparoscopic detorsion — oophorectomy is not needed if ovarian viability is preserved. In delayed diagnosis, oophorectomy of necrotic ovary is mandatory. If a predisposing lesion (cyst, tumor) caused the torsion, it is treated simultaneously. Ovary preservation is priority in reproductive age. May occur without predisposing lesion in children. US is first-choice modality for diagnosis — whirlpool sign and diminished Doppler flow are diagnostic. CT/MRI used for definitive exclusion or confirmation. If clinical suspicion is high and imaging is equivocal → diagnostic laparoscopy is recommended because risk of ovary loss is higher than expected.
Ovarian torsion is a surgical emergency. Early diagnosis and detorsion can salvage the ovary. Delayed diagnosis risks ischemic necrosis and ovarian loss. Dermoid cysts and large cysts most commonly predispose to torsion.