emDOCs Podcast – Episode 67: Ovarian Torsion

Today on the emDOCs cast with Brit Long, MD (@long_brit), we cover ovarian torsion and several myths.

Episode 67: Ovarian Torsion

Background:

• Ovarian torsion occurs when the ovary completely or partial rotates on the ligamentous supports, resulting in ovarian necrosis and infertility if missed.
• Ovarian torsion is the 5^th most common acute gynecologic disease, but it’s still rare: incidence is 5.9/1000,000 annually.
• Most patients have a cyst or mass > 5 cm.
• The classic presentation is sudden onset lower abdominal pain, associated with nausea and vomiting.
• Ovarian torsion can be a difficult diagnosis, and what we learn or classically consider can lead to misdiagnosis.

1. Myth: Ovarian torsion only occurs in women of reproductive age

• The most common patient population affected is reproductive age women (most common age is 30 years). 80% of these patients have an adnexal mass or cyst.
• 15% of cases occur during infancy or childhood. While it is more common in postmenarchal patients, in can occur in premenarchal patients or infants. Over half of pediatric patients have normal ovaries.
• Postmenopausal women can experience torsion. One study found 25% of torsion cases occurred in this age group. Another found 14/58 of torsion cases occurred after menopause. Nearly all patients in this age group have a known mass or enlarged ovary.
• Clinical Bottom Line: Ovarian torsion affects women of all ages.

2. Myth: All patients with ovarian torsion present with acute, severe pain and vomiting.

• Pain occurs due to occlusion of the vascular pedicle and ischemia. Classically its abrupt and radiates to the flank or groin, but only half present with abrupt severe pain.
• Some form of pain is present in 90%. Can present insidiously/gradually/intermittent, especially in those with polycystic ovarian syndrome or ovarian cysts.
• There may be mild to severe pelvic or abdominal pain, abdominal bloating, nausea, or vomiting. Pain can be constant or intermittent because the ovary torses and detorses.
• Fever may also be present (up to 20%).
• Don’t rely on nausea and vomiting. These are absent in 30% of patients.
• Clinical Bottom Line: The classic presentation of ovarian torsion is not always present. Patients may have gradual onset pain, intermittent pain, or very mild pain. Nausea and vomiting may not be present.

3. Myth: A normal physical exam, including pelvic exam, can rule out torsion.

• Up to a third of patients have no abdominal or pelvic tenderness on exam.
• Bimanual exam is unreliable. Patients may or may not have cervical motion tenderness, uterine tenderness, adnexal mass/tenderness.
• EM physician inter-examiner reliability for detection of pelvic masses is less than 25% and less than 32% for adnexal tenderness on bimanual examination. OBGYN exam not much better. Sensitivity for detecting adnexal mass > 5 cm is 15-36%.
• Exam is even less reliable in patients over 200 lbs and in older patients (> 55 years).
• Absence of a mass does not rule out torsion. Torsion can occur in those with a normal-sized ovary (one study found 15% of torsion cases had a normal sized ovary, which is even higher in pediatric patients).
• Clinical Bottom Line: Do not rely on a normal pelvic or bimanual examination to rule out torsion.

4. Myth: Normal arterial flow on Doppler ultrasound rules out ovarian torsion.

• Transvaginal ultrasound (TVUS) with gray-scale imaging and Doppler flow is usually our go-to imaging modality to evaluate for torsion.
• High specificity but poor sensitivity, ranging from 35-85%.
• Most common finding is an enlarged ovary, often a mass. Other signs include an ovary displaced to the midline. The string of pearls sign (enlarged ovary is lined around the periphery by follicles) suggests torsion.
• Grayscale may demonstrate a hypoechoic appearance of the ovary due to edema. Color doppler may reveal decreased or absent intraovarian venous flow, which may be followed by absent arterial flow later in the disease.
• However, the ovaries have dual blood supply (ovarian and uterine ovaries). Torsion initially occurs with lymphatic and venous outflow obstruction. Arterial inflow is not compromised until later in the disease course.
• Arterial flow is completely normal in over 25% of patients with surgery-confirmed torsion, and over half of patients will have detectable arterial flow.
• Combining findings can improve the sensitivity and specificity; can’t focusing on only vascular flow. Evaluate for free fluid within the pelvis, ovarian enlargement and edema, and vascular flow (improves sensitivity).
• The whirlpool sign is strongly suggestive of torsion (circular collection of blood vessels within an enlarged ovary or mass).
• Clinical Bottom Line: Normal arterial flow on Doppler US cannot rule out torsion. Consider using a combination of ultrasound findings.

5. Myth: A completely normal computed tomography (CT) scan of the pelvis requires an ultrasound to rule out torsion.

• CT can assist in evaluating for torsion.
• CT findings with high specificity for ovarian torsion: twisted vascular pedicle, thickened fallopian tube with target/beak-like appearance, absent or reduced ovarian enhancement with contrast, and enlarged ovary with afollicular ovarian stroma and peripherally displaced follicles. Can rule in diagnosis.
• Common findings but not specific: enlarged ovary, an adnexal mass, adnexal mass mural thickening, free pelvic fluid, fat stranding surrounding the ovary, uterine deviation towards the torsed ovary, and ovarian displacement towards the uterus.  If one of these is present, speak with OBGYN and obtain TVUS.
• If these findings are not present and there is normal ovarian size, no pelvic fluid, and no cyst or mass, sensitivity nears 100% for excluding torsion using CT.
• Clinical Bottom Line: A normal abdominal/pelvic CT significantly decreases the likelihood of torsion. Certain findings on CT are highly suggestive of torsion.

6. Myth: Pregnant patients with lower abdominal pain should have ectopic pregnancy and miscarriage ruled out. Once this is done, the evaluation is complete.

• Pregnancy increases the risk for torsion (progesterone increases the formation of ovarian cysts), and pregnant patients account for anywhere between 10% and 25% of torsion cases.
• Most cases during pregnancy occur in the first 17 weeks (81%), and 73% of these patients have undergone fertility therapy. Fertility treatments can result in ovarian hyperstimulation, further increasing the risk of ovarian cyst formation.
• Prior pelvic surgeries and tubal ligation increase the risk of torsion.
• Signs and symptoms of torsion are similar between pregnant and nonpregnant women.
• Clinical Bottom Line: Pregnant women can experience ovarian torsion, with increased risk if they are undergoing fertility treatment or have had prior torsion.

7. Myth: Surgery is useless if the patient has had symptoms for more than just a few hours.

• Torsion is time sensitive, but the exact timing of ovarian necrosis is unclear.
• Studies suggest ovarian viability ranges from several hours up to days (one study found 168 hours).
• Outcomes are worse with prolonged ischemia, so the earlier the ovary is detorsed, the higher likelihood of viability.
• Clinical Bottom Line: Patients may have symptoms for several days and still have viable ovaries after surgery. If you’re suspicious of torsion based on your history and exam, speak with your OB/GYN before obtaining imaging.  If you do not have an OB/GYN available, consult the general surgeon on call.

Summary:

• Key risk factors for ovarian torsion include the presence of an ovarian mass or cyst and prior pelvic surgery.
• Ovarian torsion most commonly affects reproductive-aged women. A significant number occur in premenarchal females, pregnant women, and postmenopausal women.
• Up to 90% of women have some form of abdominal pain, but this is not always sudden in onset and severe. Pain may be gradual and episodic. Up to 70% experience nausea and vomiting.
• Up to one-third of patients with torsion have no abdominal or pelvic tenderness.
• US is considered the primary imaging modality and has high specificity, but a normal US cannot rule out torsion.
• CT with IV contrast may show reduced or absent ovarian enhancement with contrast, peripherally displaced follicles, enlarged ovary with a follicular ovarian stroma, and a thickened fallopian tube with target/beak-like appearance.
• Consult OBGYN; there is no clear time to necrosis in ovarian torsion.

References:

• Robertson JJ, Long B, Koyfman A. Myths in the Evaluation and Management of Ovarian Torsion. J Emerg Med. 2017 Apr;52(4):449-456. doi: 10.1016/j.jemermed.2016.11.012. Epub 2016 Dec 14. PMID: 27988260.
• Bridwell RE, Koyfman A, Long B. High risk and low prevalence diseases: Ovarian torsion. Am J Emerg Med. 2022 Jun;56:145-150. doi: 10.1016/j.ajem.2022.03.046. Epub 2022 Mar 31. PMID: 35397355.