Ovarian Torsion

Etiology

The main risk factor for ovarian torsion is an ovarian mass that is 5 cm in diameter or larger. The mass increases the chance that the ovary could rotate on the axis of the two ligaments holding it in suspension. This torsion impedes venous outflow and eventually, arterial inflow.

In a study of torsions confirmed by surgery, 46% were associated with neoplasm, and 48% were associated with cysts. Of these masses, 89% were benign, and 80% of patients were under age 50. Therefore, reproductive-age females are at greatest risk of torsion.[2] However, torsion can still occur in normal ovaries, especially in the pediatric population. Pregnancy, as well as patients undergoing fertility treatments, are high risk due to enlarged follicles on the ovary.[1]

Epidemiology

Torsion occurs in females of all ages but is most common in women of childbearing age. In a 10-year review of surgical emergencies at a women’s hospital, ovarian torsion was the fifth most common, accounting for 2.7 percent. Only 20% of patients are premenarchal, and 50% of these will have a normal ovary. The majority of reproductive-age females with torsion had a benign ovarian mass.[3] Pregnancy is also an independent risk factor for torsion. In a retrospective study of patients diagnosed with torsion, 8 to 15% of them were pregnant.[1]

Pathophysiology

Torsion occurs when the ovary twists over the supporting ligaments, the infundibulopelvic ligament, and the utero-ovarian ligament. This causes swelling and obstruction of blood flow. Initially, the venous outflow is obstructed, and later arterial inflow is also interrupted due to increased swelling, leading to necrosis of the ovary, infarction, hemorrhage, and possibly peritonitis. The right side has been seen more commonly than left-sided torsion, which is thought to be due to increased space in the right pelvis due to the location of the sigmoid colon in the left.[4]

History and Physical

The patient most commonly will present with lower abdominal pain or pelvic pain. Pain can be sharp, dull, constant, or intermittent. Pain may radiate to the abdomen, back, or flank.[5] One study showed that post-menopausal women commonly presented with dull, constant pain when compared to premenopausal, who more commonly had sharp stabbing pain. Symptoms may or may not be intermittent if the ovary is torsing and detorsing.

The patient may also have associated nausea and vomiting. In one study of children and adolescents with lower abdominal pain, vomiting was found to be an independent risk factor for ovarian torsion.[6] The patient may or may not already have a known adnexal mass, which predisposes them to torsion.

Fever may be present if the ovary is already necrotic. The patient could also have abnormal vaginal bleeding, or discharge if torsion involves a tubo-ovarian abscess. Infants with torsion may present with feeding intolerance or inconsolability.

Physical exam in the patient is variable. The patient may have abdominal tenderness focally in the lower abdomen, pelvic area, diffusely, or not at all. Up to one-third of patients were found to have no abdominal tenderness. There could also be an abdominal mass. If the patient has guarding, rigidity, or rebound, there may already be necrosis of the ovary. Every patient should also have a pelvic exam to better evaluate for masses, discharge, and cervical motion tenderness.

Evaluation

Laboratory testing should include a complete blood count, complete metabolic panel, and a serum hCG. CBC may show a leukocytosis, or anemia if the torsion is causing hemorrhage. Hcg is especially important since pregnancy is a risk factor for torsion. These laboratory abnormalities are non-specific, and most often, the lab values will be normal in torsion.

The imaging study of choice is ultrasound with doppler.  Both a transvaginal and pelvic ultrasound should be done. The sensitivity of ultrasound for ovarian torsion is dependent on many factors, including technician skill and patient anatomy, but is reported to be around 84%.[7] In one study, the most sensitive findings on ultrasound were ovarian edema, abnormal ovarian blood flow, and relative enlargement of the ovary.[8] There may also be free fluid or the whirlpool sign, which is thought to be due to the twisting of the vascular pedicle in cross-section.[9] 

Blood flow should be assessed as compared to the contralateral ovary. Due to the ovaries having dual blood supply, the complete lack of flow is not necessary to be symptomatic. The ovary may also not be torsed at the time of ultrasound, which is why ultrasound alone cannot rule out ovarian torsion. CT and MRI are not generally used to diagnose ovarian torsion but are commonly done to rule out other abdominal pathology such as acute appendicitis.

The definitive diagnosis of ovarian torsion is made by direct visualization of a rotated ovary during surgery. For this reason, if clinical suspicion remains high with relatively normal labs and ultrasound imaging, the patient must have surgical evaluation.

Treatment / Management

The treatment of ovarian torsion is surgical detorsion, preferably by a gynecologist. In reproductive age females, salvage of the ovary should be attempted, and the surgeon must evaluate the ovary for viability. Most often, the approach to surgery should be laparoscopic and involves direct visualization of a twisted ovary. The evaluation of viability is mostly by visualization. A dark, enlarged ovary with hemorrhagic lesions may have compromised blood flow but is often salvageable.[10] (B2)

After detorsion, ovaries were found to be functional in greater than 90% of patients who underwent detorsion. This was assessed by the appearance of the adnexa on ultrasound, including follicular development on the ovaries.[11] Therefore, surgery with adnexal sparing is the management of choice. Rarely, if the ovary appears necrotic and gelatinous beyond possible salvage, the surgeon may choose to perform a salpingo-oophorectomy. The surgeon may also perform cystectomy if a benign cyst is present. If the cyst appears to be malignant, or if the woman is post-menopausal, salpingo-oophorectomy is the preferred management.(B2)

Differential Diagnosis

There are many differentials for abdominal pain in a female. In a patient of childbearing age, ectopic pregnancy must first be ruled out with a beta hCG. If the beta hCG is negative, then this can essentially be ruled out. If positive, then an intrauterine pregnancy on ultrasound dramatically decreases the risk of ectopic but does not rule out heterotopic pregnancy. A ruptured ovarian cyst can also present like an ovarian torsion. Both may also have free fluid in the pelvis on ultrasound. However, cyst rupture typically causes sudden onset of sharp pain, which commonly occurs during sexual intercourse.

A tubo-ovarian abscess may present with lower pelvic pain, which is usually more gradual in onset and associated with fever. Appendicitis can present with right-sided pelvic pain, nausea, vomiting, and fever. Lab values may show leukocytosis, and CT imaging should aid in differentiating it from ovarian pathology.[12] Other differentials include pyelonephritis, diverticulitis, and pelvic inflammatory disease.

Prognosis

Ovarian torsion is not usually life-threatening, but it is organ threatening. In premenopausal women, surgery with adnexal sparring is now the preferred treatment, and the majority of women had normal-appearing adnexa on ultrasound after surgery.[13] Ovarian salvage is increased in patients with less time from the onset of symptoms to surgical intervention. In postmenopausal women, salpingo-oophorectomy is done to prevent reoccurrence. This approach is also used in women with a mass suspicious for malignancy. The majority of ovarian masses are benign. Some case reports show less than 2% of torsions involving a malignant lesion. However, the chances of a malignant lesion involved in torsion are increased in the postmenopausal group.[1]

Complications

The main complication of ovarian torsion is the inability to salvage the ovary and the need for salpingo-oophorectomy. This may affect fertility in a woman of childbearing age. Other complications of torsion include abnormal pelvic anatomy that may contribute to infertility, such as adhesions, or atrophied ovaries.[14] There may be complications from the surgery itself, such as infection or venous thromboembolism. The risk of post-operative infection is increased when necrotic tissue is already present.[15]