For suspected ruptured ovarian cyst causing acute pain, what is the diagnostic imaging modality of choice?

• A. Pelvic/transvaginal ultrasound
• B. CT abdomen
• C. MRI pelvis
• D. Abdominal X-ray

Answer: (A)

When acute pelvic pain is suspected to be from a ruptured ovarian cyst, the best initial imaging test is ultrasound of the pelvis, ideally performed transvaginally. This modality quickly provides high-resolution images of the ovaries and adnexa, allows you to see the cyst and its characteristics, and can detect free intraperitoneal fluid or a hematoma that would accompany rupture. It is noninvasive, free of radiation, and can be done at the bedside, which is crucial in the acute setting. The transvaginal approach offers superior detail for adnexal structures compared with other imaging modalities, making it the most informative for this scenario.

CT abdomen can identify free fluid and help rule out other intra-abdominal causes, but it is less sensitive for characterizing ovarian pathology and involves radiation. MRI pelvis provides excellent soft-tissue detail but is not practical as a first-line test in acute care due to time, availability, and cost. Abdominal X-ray is not useful for evaluating ovarian cyst rupture.