How is ovarian torsion diagnosed?

Diagnosis of Ovarian Torsion

Ultrasound with Doppler is the first-line imaging modality for diagnosing ovarian torsion, with key findings including unilaterally enlarged ovary (>4 cm or volume >20 cm³), peripheral follicles, abnormal or absent venous flow (100% sensitivity, 97% specificity), and the whirlpool sign (90% sensitivity). 1

Clinical Presentation

Ovarian torsion typically manifests as:

• Severe, constant pelvic or abdominal pain that may fluctuate in intensity but rarely completely resolves without intervention 1
• Nausea and vomiting occur in approximately 70% of cases 2
• Pain onset may be sudden or gradual—not always acute, which can delay diagnosis 2
• A palpable laterouterine pelvic mass may be present on examination 3

Critical pitfall: Ovarian torsion can mimic appendicitis, renal colic, or urinary tract infection, leading to diagnostic delays 1, 4. The anatomical proximity of the ovaries to the bladder can cause dysuria, mimicking UTI symptoms 1.

Diagnostic Imaging Algorithm

First-Line: Pelvic Ultrasound with Doppler

Combined transabdominal and transvaginal ultrasound provides the most comprehensive assessment 1

Key ultrasound findings include:

• Unilaterally enlarged ovary (>4 cm diameter or volume >20 cm³) 1, 4
• Peripheral follicles (present in up to 74% of cases) 1, 4
• Abnormal or absent venous flow (100% sensitivity, 97% specificity)—this is the most sensitive finding 1
• Whirlpool sign (twisted vascular pedicle and supporting ligaments) with 90% sensitivity in laparoscopically confirmed cases 1, 4
• Stromal edema and surrounding fluid 1

Diagnostic performance:

• Doppler ultrasound: 80% sensitivity, 88% specificity 1
• Grayscale ultrasound alone: 79% sensitivity, 76% specificity 1

Critical Diagnostic Pitfall

Normal arterial blood flow on ultrasound does NOT rule out ovarian torsion 1, 4. Torsion can be intermittent or partial, and venous flow abnormalities are more sensitive than arterial findings 1. A normal ultrasound examination cannot exclude the diagnosis 2.

Second-Line: MRI (When Ultrasound Inconclusive)

When ultrasound findings are equivocal but clinical suspicion remains high, MRI provides 80-85% sensitivity 1, 4

MRI findings include:

• Enlarged ovary with stromal edema 1
• Absent or diminished enhancement 1
• Surrounding fluid 1

Alternative: CT Imaging

CT is not routinely used in young females due to radiation exposure, but is increasingly performed in emergency departments for acute abdominal pain 5. CT may be the first imaging modality to identify ovarian torsion when non-gynecological causes are initially suspected 5.

CT findings include:

• Asymmetrically enlarged ovary with or without an underlying mass 1
• Twisted pedicle (swirling of vascular pedicle) 1
• Abnormal or absent ovarian enhancement 1
• Subacute ovarian hematoma 1
• Deviation of the uterus to the side of the twist 1
• Engorged vessels on the twisted side 1

Risk Factors and Populations

• Presence of an ovarian mass or cyst is the main risk factor 2, 6
• Most commonly affects reproductive-aged women, but can occur in premenarchal females, pregnant women (including postpartum), and postmenopausal women 3, 2, 6
• Occurs in 2-15% of patients undergoing surgical treatment of adnexal masses 6

Clinical Integration

Once ovarian torsion is suspected based on clinical presentation and imaging, immediate surgical intervention with diagnostic laparoscopy is indicated 4, 6. Early and timely recognition with prompt intervention is crucial to preserve ovarian function and minimize morbidity 3, 7. The risk of ovarian damage or loss outweighs the risk of diagnostic laparoscopy in patients of reproductive age 7.