Torsio Ovarium

01Pathophysiology

Ovarian torsion occurs when the ovary rotates along the axis of its supporting ligaments, namely the infundibulopelvic ligament (which carries the ovarian artery and vein) and the utero-ovarian ligament. This rotation kinks the vascular pedicle and progressively obstructs blood flow.

The sequence of vascular compromise follows a predictable pattern. Because veins and lymphatics are low-pressure systems, they are occluded first. This leads to venous congestion and edema of the ovary, which causes the ovary to enlarge. As the ovary swells, interstitial pressure rises, and eventually the arterial inflow is also compromised. If left untreated, this progresses to hemorrhagic infarction and necrosis. This is why imaging classically shows an enlarged, edematous ovary, sometimes with peripheral follicles pushed to the surface ("string of pearls" appearance from stromal edema).

The reason ovarian masses (especially those 5 cm or larger) predispose to torsion is straightforward: a heavier or larger ovary has more momentum and is more likely to rotate around its pedicle. Dermoid cysts (mature cystic teratomas) are the single most common benign neoplasm associated with torsion because they are heavy, solid-cystic masses that shift the center of gravity. Importantly, malignant tumors rarely cause torsion because adhesions from local invasion anchor the ovary in place.

The pain in ovarian torsion is sudden and severe because the peritoneum overlying the ovary is being stretched by rapid edema, and the ischemia itself triggers visceral nociceptors. The characteristic nausea and vomiting result from peritoneal irritation and vagal stimulation, and this association is so strong that it helps differentiate torsion from other causes of acute pelvic pain.

The right ovary torsion is more common than the left. This is because the sigmoid colon occupies the left lower quadrant and physically limits the left ovary's range of motion. The right side has no such anatomic barrier.

02Classification and Clinical Manifestation

By Structure Involved

By Degree of Vascular Compromise

Clinical Manifestation by Population

03Diagnostic Workup

Pelvic ultrasound with Doppler is the best initial test. The hallmark finding is a unilaterally enlarged, edematous ovary. Doppler evaluation may show decreased or absent blood flow, and the "whirlpool sign" (a spiral pattern of the twisted vascular pedicle) is considered highly characteristic when identified.

However, the single most important teaching point for exam purposes is this: normal Doppler flow does not exclude ovarian torsion. Because torsion can be intermittent (the ovary torsion and then partially reduce), arterial flow may be transiently preserved at the time of imaging. Additionally, dual blood supply from the ovarian artery and uterine artery collaterals can maintain detectable flow even when the pedicle is twisted. If clinical suspicion is high, do not be reassured by normal Doppler findings. Proceed to surgical exploration.

Other supportive ultrasound findings include free fluid in the pelvis (from transudation of the congested ovary), peripherally displaced follicles, and a coexisting ovarian mass.

A serum beta-hCG must be obtained in every reproductive-age woman with acute pelvic pain. This is not optional. It rules out ectopic pregnancy, which is the primary life-threatening differential.

CT scan is not the preferred initial study, but many patients with acute abdominal pain undergo CT before the clinical picture points toward a gynecologic cause. On CT, you may see the ovary displaced from its expected position, enlarged and edematous, sometimes with the "target sign" from the twisted pedicle. While CT can raise suspicion, it is not reliable enough to confirm or exclude torsion.

The gold standard for diagnosis is direct surgical visualization via laparoscopy. This is where the twisted pedicle is seen directly, and the procedure simultaneously serves as treatment (detorsion). The decision to operate is clinical: if clinical suspicion is high, do not delay surgery for additional imaging.

04Management and Treatment

The cornerstone of management is emergency surgical intervention. Ovarian torsion is a surgical emergency because delays lead to irreversible ischemic damage and potential loss of the ovary.

Laparoscopic detorsion with ovarian conservation is the preferred approach in reproductive-age women. Even if the ovary appears dusky or congested at surgery, the current evidence supports untwisting and observing, because ovaries that look ischemic at the time of surgery often regain viability after reperfusion. The outdated concern that detorsing a necrotic ovary would release emboli or toxins into the circulation has been largely disproven. Therefore, the modern approach is to detorse first and reassess. Oophorectomy is reserved for tissue that is clearly gangrenous and nonviable, or in postmenopausal women where malignancy needs to be excluded.

If an ovarian mass (such as a dermoid cyst) is identified as the lead point, cystectomy should be performed at the same time to reduce the risk of recurrence. Simply detorsing without removing the precipitating mass leaves the patient vulnerable to re-torsion.

For patients with recurrent torsion (especially in the pediatric population where normal ovaries may torse due to ligamentous laxity), oophoropexy can be performed. This involves surgically fixing the ovary to the pelvic sidewall or the posterior surface of the uterus.

Pain management with IV analgesics (ketorolac 15 to 30 mg IV or morphine 0.1 mg/kg IV) and antiemetics (ondansetron 4 mg IV) should be initiated in the emergency department, but these are temporizing measures. Definitive treatment is surgical, and analgesic response should never be used to downgrade clinical suspicion.

In pregnant patients, laparoscopy is safe and remains the preferred approach. The principles are identical. In the second and third trimesters, the patient should be positioned with a left lateral tilt to prevent compression of the inferior vena cava by the gravid uterus.

05Differential Diagnosis and Distractors

06Traps and High-Yield Pearls

The single most tested "gotcha" on this topic is the normal Doppler flow trap. Students who see "Doppler shows preserved arterial flow" in a vignette often incorrectly rule out ovarian torsion and pivot to a less urgent diagnosis. This is exactly what the test-writer wants you to do. Remember: Doppler has a sensitivity of roughly 60 to 70% for torsion, meaning it misses a substantial number of cases. When clinical suspicion is high (sudden pelvic pain, nausea, enlarged ovary), the next step is surgical exploration regardless of Doppler findings.

The second common error is confusing ovarian torsion with a ruptured ovarian cyst. Both present with sudden pelvic pain and free fluid. The discriminator is the trajectory of pain: ruptured cyst pain peaks and then gradually improves, while torsion pain persists or escalates. Additionally, the ovary in torsion is enlarged and edematous, whereas in a ruptured cyst the ovary may appear deflated or normal-sized.

Students also struggle with the management question: the answer to "what is the next best step" in a clinically suspected ovarian torsion is almost always surgery (laparoscopy), not further imaging. If the vignette gives you a classic presentation with high suspicion, do not order a CT or MRI. Go to the operating room.

Finally, remember the fertility-preservation principle. The answer is almost never oophorectomy in a young woman unless the ovary is explicitly described as necrotic or gangrenous. Detorsion with ovarian conservation is the standard of care, even when the ovary appears ischemic intraoperatively. Test-writers reward you for choosing the less aggressive, fertility-sparing option.