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Difficulty: MediumInterpreting Imaging Results

A 26-year-old nulligravid woman presents to the emergency department with sudden-onset, sharp, right lower quadrant abdominal pain that began 4 hours ago. The pain started abruptly while she was exercising at the gym. Her last menstrual period was 15 days ago, and she reports regular 28-day cycles. She has no history of sexually transmitted infections or prior abdominal surgeries. Vital signs include a temperature of 37.1°C (98.8°F), blood pressure of 118/76 mmHg, heart rate of 88/min, and respiratory rate of 16/min. Physical examination reveals focal tenderness to deep palpation in the right lower quadrant without rebound or guarding. A urine pregnancy test is negative. Complete blood count and basic metabolic panel are within normal limits.

A transvaginal pelvic ultrasound is performed and demonstrates a normal uterus and left ovary. The right ovary is enlarged, measuring 5.2 cm in its greatest dimension, and contains a 4.5-cm, thin-walled cystic structure. The cyst exhibits a fine, interlacing, reticular pattern of internal echoes (a "lacy" or "fishnet" appearance). There is no solid nodularity, thick septations, or significant free pelvic fluid. Color Doppler interrogation reveals robust, symmetric arterial and venous flow to the right ovarian parenchyma.

Based on the clinical presentation and imaging findings, which of the following is the most appropriate next step in management?

  1. Discharge home with oral analgesics and outpatient follow-upAnswer
  2. B
    Diagnostic laparoscopy
  3. C
    Computed tomography of the abdomen and pelvis with intravenous contrast
  4. D
    Admission for intravenous ceftriaxone and doxycycline
  5. E
    Measurement of serum cancer antigen 125 (CA-125) levels

Answer

Discharge home with oral analgesics and outpatient follow-up
The correct management is to discharge the patient home with oral analgesics and arrange for outpatient follow-up. The patient's presentation (sudden onset of pain at mid-cycle) and ultrasound findings (a thin-walled cyst with a fine, interlacing, reticular pattern of internal echoes) are classic for a hemorrhagic corpus luteum cyst. The 'lacy' or 'cobweb' appearance represents fibrin strands forming within the resolving hematoma inside the cyst. Because there is no evidence of ovarian torsion (she has normal Doppler flow) and she is hemodynamically stable with no signs of massive intraperitoneal bleeding (no large volume free fluid), this condition is benign and self-limiting. Surgical intervention or further diagnostic workup is not indicated.

Step-by-Step Solution

1
Analyze the clinical presentation.
The patient is a young, hemodynamically stable woman experiencing sudden-onset right lower quadrant pain mid-cycle (day 15 of a 28-day cycle) with a negative pregnancy test and normal white blood cell count.
This establishes a differential diagnosis focused on acute gynecologic pathology, such as ovarian torsion, ruptured cyst, or hemorrhagic cyst, while ruling out ectopic pregnancy and making pelvic inflammatory disease less likely.
2
Interpret the specific imaging findings.
The transvaginal ultrasound shows a right ovarian cyst with a 'lacy' or 'reticular' pattern of internal echoes, thin walls, no solid components, and normal Doppler blood flow.
A 'lacy' or 'spider web' appearance of internal echoes is pathognomonic for a bleeding or hemorrhagic corpus luteum cyst (fibrin strands). The normal Doppler flow effectively rules out ovarian torsion, and the lack of solid components rules out malignancy.
3
Determine the appropriate management based on the diagnosis.
Because the patient is hemodynamically stable, has a benign hemorrhagic cyst, and lacks significant free pelvic fluid, the condition is self-limiting and requires only symptomatic care.
Uncomplicated hemorrhagic cysts typically resolve spontaneously over 1 to 2 menstrual cycles, making supportive care with analgesics the standard of care.

Key Concept

Hemorrhagic corpus luteum cysts typically present with sudden pelvic pain and display a pathognomonic 'lacy' or 'reticular' pattern on ultrasound. In hemodynamically stable patients, they require only conservative management with analgesics.
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Interpreting Imaging Results

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