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Difficulty: HardInterpreting Imaging Results

A 24-year-old nulligravid woman comes to the emergency department due to sudden-onset, severe, right-sided pelvic pain that began 4 hours ago. The pain is colicky, radiates to her right flank, and is associated with multiple episodes of nausea and vomiting. Her last menstrual period was 3 weeks ago. She has no history of sexually transmitted infections or prior abdominal surgeries. Her temperature is 37.1°C (98.8°F), blood pressure is 122/76 mm Hg, and pulse is 108/min. Physical examination reveals exquisite tenderness to palpation in the right lower quadrant with voluntary guarding, but no rebound tenderness. Pelvic examination demonstrates a palpable, tender right adnexal mass; there is no cervical motion tenderness. A urine pregnancy test is negative. Complete blood count shows a leukocyte count of 11,500/mm³. A transvaginal ultrasound is performed. The right ovary measures 6.5 x 5.0 x 4.5 cm and exhibits central stromal edema with multiple small, peripherally displaced follicles. Color Doppler evaluation of the right ovary demonstrates absent venous flow but reveals preserved arterial waveforms. The left ovary and uterus appear unremarkable. A small amount of free fluid is noted in the posterior cul-de-sac. What is the most appropriate next step in the management of this patient based on the sonographic findings?

  1. Diagnostic laparoscopyAnswer
  2. B
    Discharge home with nonsteroidal anti-inflammatory drugs and outpatient gynecology follow-up
  3. C
    Computed tomography of the abdomen and pelvis with intravenous contrast
  4. D
    Intravenous administration of ceftriaxone and doxycycline
  5. E
    Repeat pelvic ultrasound in 48 hours

Answer

Diagnostic laparoscopy
The correct answer is diagnostic laparoscopy. The clinical vignette combined with the specific ultrasound findings (enlarged ovary, peripherally displaced follicles, and absent venous flow) points definitively to ovarian torsion. A critical teaching point is that the presence of arterial Doppler flow does not rule out torsion due to the dual blood supply of the ovary and the fact that high-pressure arterial inflow often persists after low-pressure venous outflow has collapsed. Immediate surgical intervention is required to untwist the adnexa and preserve ovarian function.

Step-by-Step Solution

1
Evaluate the acute clinical presentation.
The combination of sudden-onset unilateral pelvic pain, nausea, vomiting, and a palpable adnexal mass in a reproductive-age woman is highly suspicious for ovarian torsion.
Torsion typically presents with severe colicky pain and visceral symptoms due to acute adnexal ischemia.
2
Interpret the transvaginal ultrasound morphology.
The right ovary is significantly enlarged (>4 cm) with central edema and peripherally displaced follicles, often referred to as the 'string of pearls' sign.
As the infundibulopelvic ligament twists, low-pressure venous and lymphatic drainage is compromised first, leading to massive stromal engorgement and transudation of fluid that pushes follicles to the periphery.
3
Correlate the Doppler flow findings with the pathophysiology of early torsion.
The presence of arterial flow does not exclude the diagnosis of torsion.
The ovary receives a dual blood supply from both the ovarian and uterine arteries. Furthermore, high-pressure arterial inflow can persist long after the low-pressure venous outflow has been completely occluded.
4
Determine the necessary intervention based on the confirmed imaging diagnosis.
Urgent diagnostic laparoscopy with detorsion is indicated.
Ovarian torsion is a surgical emergency; delaying intervention increases the risk of irreversible ischemic necrosis and loss of the affected ovary.

Key Concept

Arterial flow on Doppler ultrasound does not rule out ovarian torsion; the diagnosis relies heavily on morphologic features such as asymmetric ovarian enlargement, stromal edema, and peripherally displaced follicles.
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Interpreting Imaging Results

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