I’m a reproductive‑age woman with ovarian volumes of about 8 mL on the right and 10 mL on the left, a string‑of‑pearls follicle pattern and right iliac‑fossa tenderness—does this indicate polycystic ovary syndrome or an acute condition such as ovarian torsion, and what should be the immediate next step?

Ovarian Volumes of 8–10 mL with String-of-Pearls Pattern and Right Iliac Fossa Tenderness: PCOS versus Acute Pathology

Immediate Assessment Priority

Your ovarian volumes of 8 mL (right) and 10 mL (left) do NOT meet the ultrasound threshold for polycystic ovarian morphology, which requires at least one ovary ≥10 mL, but the right iliac fossa tenderness is a red flag that demands immediate evaluation for ovarian torsion or other acute pathology before considering PCOS. 1

Critical Distinction: Acute versus Chronic Pathology

Ovarian Torsion Must Be Ruled Out First

• Right iliac fossa tenderness in the presence of ovarian findings requires urgent Doppler ultrasound to assess ovarian blood flow, as torsion can occur with normal-appearing ovaries and represents a surgical emergency that can lead to ovarian necrosis within 4–6 hours. 1
• Acute onset of pain, nausea, vomiting, or intermittent sharp pain episodes strongly suggest torsion rather than PCOS, which is typically painless. 1
• If Doppler shows absent or reversed diastolic flow, immediate surgical consultation is mandatory regardless of other findings. 1

Why This Likely Is NOT PCOS Based on Ultrasound

• The right ovary at 8 mL falls below the diagnostic threshold of ≥10 mL required for polycystic ovarian morphology, and while the left ovary at 10 mL meets the minimum threshold, the presence of acute tenderness makes PCOS diagnosis premature. 1
• Using modern ultrasound technology with ≥8 MHz transducers, the primary diagnostic criterion is ≥20 follicles (2–9 mm diameter) per ovary, which has 87.64% sensitivity and 93.74% specificity—the "string-of-pearls" description alone is insufficient without documented follicle counts. 1, 2
• Ovarian volume alone has lower diagnostic accuracy (81.48% sensitivity, 81.04% specificity) compared to follicle number per ovary, and should only be used when precise follicle counting is impossible. 1

Diagnostic Algorithm for Your Situation

Step 1: Emergency Exclusion (Within Hours)

• Obtain color Doppler ultrasound of both ovaries immediately to assess arterial and venous flow patterns. 1
• Measure peak systolic velocity and resistive index—absent venous flow or high resistive index (>0.70) suggests torsion. 1
• Assess for free fluid in the pelvis, which may indicate hemorrhage, rupture, or infection. 1

Step 2: Complete Ultrasound Characterization (If Torsion Excluded)

• Request transvaginal ultrasound with ≥8 MHz transducer to obtain accurate follicle number per ovary (FNPO), counting all follicles 2–9 mm throughout the entire ovary using slow scanning technique. 1, 2
• Document three-dimensional measurements of each ovary to calculate volume using the formula: length × width × thickness × 0.523. 1, 3
• Ensure no corpus luteum, dominant follicles ≥10 mm, or cysts are present, as these invalidate PCOM assessment and require repeat scanning during ovarian quiescence. 1, 3
• Note that follicle number per ovary (FNPO) shows the strongest right-left correlation and is the most reliable unilateral marker—assessment of a single ovary is acceptable if FNPO is used. 4

Step 3: Clinical and Biochemical Assessment for PCOS (Only After Acute Pathology Excluded)

PCOS requires at least two of three Rotterdam criteria:

1. Oligo- or anovulation: Menstrual cycles >35 days or <8 cycles per year. 1, 5, 6
2. Clinical or biochemical hyperandrogenism:
   • Clinical: Hirsutism (Ferriman-Gallwey score ≥6), acne, or male-pattern alopecia. 5, 6
   • Biochemical: Total testosterone via LC-MS/MS (74% sensitivity, 86% specificity) or calculated free testosterone (89% sensitivity, 83% specificity). 5, 7
3. Polycystic ovarian morphology: ≥20 follicles per ovary and/or ovarian volume ≥10 mL. 1

Key laboratory tests to order:

• Total testosterone or free testosterone (preferably LC-MS/MS method, which has 92% specificity versus 78% for immunoassays). 5, 7
• TSH to exclude thyroid disease causing menstrual irregularity. 5, 7
• Prolactin (morning resting level) to exclude hyperprolactinemia. 5, 7
• 2-hour oral glucose tolerance test with 75g glucose load, regardless of BMI, as insulin resistance occurs independently of body weight. 5, 6
• Fasting lipid profile to assess cardiovascular risk. 5, 7

Step 4: Exclude Alternative Diagnoses

Before confirming PCOS, rule out:

• Functional hypothalamic amenorrhea (FHA): History of excessive exercise, stress, or low body weight can cause amenorrhea with multifollicular ovaries that mimic PCOM. 1
• Cushing's syndrome: Buffalo hump, moon facies, hypertension, abdominal striae warrant dexamethasone suppression testing. 5, 6
• Androgen-secreting tumors: Rapid onset of virilization or testosterone >2.5 nmol/L requires further imaging. 5, 6
• Non-classic congenital adrenal hyperplasia: Measure 17-hydroxyprogesterone if DHEAS elevated. 5, 7

Common Pitfalls to Avoid

• Never diagnose PCOS in the presence of acute pelvic pain without first excluding surgical emergencies—torsion, hemorrhagic cyst rupture, and tubo-ovarian abscess can all present with ovarian enlargement. 1
• Do not rely on ovarian volume alone when only one ovary meets the 10 mL threshold—follicle number per ovary is far more reliable and should be the primary criterion. 1, 4, 2
• Avoid using ultrasound for PCOS diagnosis if gynecological age is <8 years post-menarche, as multifollicular ovaries are physiologically normal in this population with poor specificity (high false-positive rate). 1
• Do not use Anti-Müllerian Hormone (AMH) levels as a diagnostic substitute for ultrasound or as a standalone test, as assays lack standardization and validated cut-offs despite showing 92% sensitivity and 97% specificity at ≥35 pmol/L. 1, 5, 7
• Remember that up to 30% of healthy women in the general population have polycystic ovarian morphology on ultrasound without PCOS—ultrasound findings must be interpreted in clinical context. 1, 3

Immediate Next Step

Obtain urgent color Doppler ultrasound to assess ovarian perfusion and rule out torsion, given the right iliac fossa tenderness. 1 If torsion is excluded and pain resolves, proceed with comprehensive ultrasound characterization including precise follicle counting, followed by clinical assessment for menstrual irregularity and hyperandrogenism, and appropriate laboratory testing to determine if Rotterdam criteria for PCOS are met. 1, 5, 6