OBG Radiology Case - Ovarian Torsion

Question 1

What is the most common gynecologic surgical emergency?

Answer 1

Ovarian torsion

Question 2

What are the findings of ovarian torsion on U/S?

Answer 2

1. Ovarian enlargement
2. String of pearls sign
3. Little to no intra-ovarian venous flow and sometimes absent arterial flow on color and waveform Doppler
4. Whirlpool sign
5. Heterogenous appearance of the ovarian stroma (sometimes seen due to edema and hemorrhage from an underlying ovarian lesion)
6. Free pelvic fluid (>80% of cases)

Question 3

What is the most common sonographic finding of ovarian torsion on U/S and what causes it?

Answer 3

Ovarian enlargement, secondary to impaired venous and lymphatic drainage

Question 4

What is the string of pearls sign?

Answer 4

Several immature follicles along the periphery of the ovary are displaced away from the center by edema

Question 5

Why does normal vascularity on Doppler not exclude torsion?

Answer 5

Torsion may be intermittent or the ovary can be fed by a dual blood supply from both ovarian and uterine arteries

Question 6

What is the whirlpool sign?

Answer 6

The twisted pedicle of the affected ovary; relatively specific for torsion

Question 7

What are the findings of ovarian torsion on CT?

Answer 7

1. Enlarged ovary with a possible underlying lesion, may appear in an abnormal location
2. Lack of enhancement may be seen after administration of IV contrast
3. Surrounding fat stranding, edema, coiled ovarian vessels, free fluid

Question 8

What are the findings of ovarian torsion on MRI?

Answer 8

Enlarged, edematous ovary in an abnormal location; with contrast enhancement, the coiled ovarian vessels may be visualized with the “whirlpool” sign

Question 9

What is the imaging method of choice in suspected cases of ovarian torsion and why?

Answer 9

Both TA and TV U/S with color and waveform Doppler analysis; can show morphologic and physiologic changes in the ovary and help determine whether blood flow is impaired (helps predict viability).

Question 10

Torsion of the right ovary can be mistaken for ___ and US may help differentiate the two.

Answer 10

Appendicitis

Question 11

Why should both ovaries always be scanned?

Answer 11

To compare symptomatic and asymptomatic sides

Question 12

When would CT or MRI be needed to make a definitive diagnosis?

Answer 12

When U/S findings are non-diagnostic; CT typically used (MRI too slow0

+ can help r/o other causes of lower abdominal pain, can rule out presence of a pelvic mass (both help r/o torsion)
- unable to evaluate presence/absence of blood flow

Question 13

What are the Appropriateness Criteria for acute pelvic pain in the reproductive age female?

Answer 13

Both TV and TA pelvic U/S should be initial studies with Doppler used as an adjunct. If inconclusive or non-diagnostic, an MRI of the abdomen and pelvis can be performed. CT is not recommended due to radiation risk.

Question 14

What are the Appropriateness Criteria for clinically suspected adnexal mass?

Answer 14

TV and TA U/S with Doppler is the test of choice

Question 15

What are the clinical settings in which you will consider ovarian torsion?

Answer 15

1. Sudden onset of sharp, usually unilateral lower abdominal pain or pelvic pain (90%)
2. N/V (40-70%)
3. Unilateral, tender adnexal mass (86-95%)
4. Fever and vaginal bleeding are uncommon (2-20% and 4%, respectively)
5. Abnormal genital tract bleeding (4%)

Question 16

What are the risk factors for developing ovarian torsion?

Answer 16

1. Pathologically enlarged ovaries (>6cm) may alter the position of the fallopian tube
2. Ovarian masses (tumors, cysts)
3. Women of reproductive age, during pregnancy, women undergoing ovulation induction for treatment of infertility (since many of the masses are associated with the reproductive cycle, ie corpus luteum, ovulation induction, etc.)
4. In pregnancy secondary to ovarian enlargement + laxity of the supporting tissues
5. Increased length of the ovarian ligaments

Question 17

Torsion of the ovary usually occurs with torsion of the ___ as well as their shared vascular pedicle around the ___.

Answer 17

Fallopian tube; broad ligament

Question 18

Torsion of a normal ovary more commonly occurs in young children with developmental abnormalities, such as ___ or ___.

Answer 18

Excessively long fallopian tubes; absent mesosalpinx

Question 19

What is the primary risk factor for ovarian torsion?

Answer 19

Ovarian mass

Question 20

What is the normal ovary size for a woman of childbearing age?

Answer 20

3-5cm in length