Getting the Right PCOS Diagnosis: Why So Many Women Are Misdiagnosed

PCOS is simultaneously one of the most over-diagnosed and most under-diagnosed conditions in Indian gynaecology. Thousands of women receive a PCOS label based on a single ultrasound showing "multiple follicles" — without the hormonal assessment or clinical evaluation that a correct diagnosis requires. At the same time, women with lean PCOS, or with atypical presentations, go years without the correct diagnosis while their symptoms are attributed to stress or dismissed as normal variation.

A correct PCOS diagnosis matters because it determines treatment. An incorrect diagnosis leads to incorrect treatment — or no treatment at all — with real consequences for health and fertility.

The Rotterdam Criteria: The Diagnostic Standard

PCOS is diagnosed using the Rotterdam criteria (2003, updated since), which require the presence of at least two of three features, after exclusion of other causes:

• Oligoanovulation: Irregular or absent ovulation — typically reflected in cycles longer than 35 days, fewer than 8 cycles per year, or absent periods
• Clinical or biochemical hyperandrogenism: Clinical signs (acne, hirsutism, androgenic alopecia) or elevated androgen levels on blood testing (elevated total testosterone, elevated free testosterone, elevated DHEAS)
• Polycystic ovarian morphology (PCOM) on ultrasound: More than 20 follicles per ovary (using modern high-frequency transvaginal ultrasound), or total ovarian volume above 10 ml

Having all three features is not required for diagnosis. Having polycystic ovaries alone on ultrasound, without either irregular cycles or androgen excess, is NOT PCOS. And having irregular cycles with elevated androgens, without polycystic ovaries, IS PCOS. The ultrasound is one of three criteria — not the diagnosis by itself.

The Most Common Misdiagnosis: Ultrasound Alone

In Indian practice, a significant proportion of "PCOS diagnoses" are made based on a single transvaginal or transabdominal ultrasound report showing "multiple small follicles in the ovaries" — with no hormonal testing and no clinical evaluation of ovulation regularity or androgen status.

This is incorrect practice. Polycystic ovarian morphology on ultrasound is found in approximately 20 to 30% of reproductively normal women — women with regular cycles, no androgen excess, and entirely normal fertility. These women do not have PCOS. Telling them they do causes unnecessary anxiety, incorrect treatment, and — in the fertility context — inappropriate escalation of intervention.

The correct approach: ultrasound findings of polycystic morphology must be interpreted alongside cycle history and androgen assessment before a PCOS diagnosis is applied.

Other Conditions That Mimic PCOS

The Rotterdam criteria explicitly require exclusion of other causes of irregular cycles and androgen excess before PCOS is confirmed:

• Thyroid disease: Hypothyroidism and hyperthyroidism both cause irregular cycles. TSH testing is mandatory.
• Hyperprolactinaemia: Elevated prolactin causes anovulation with polycystic-appearing ovaries on ultrasound. Prolactin should be measured in every woman with irregular cycles.
• Non-classical congenital adrenal hyperplasia (NCCAH): Caused by 21-hydroxylase enzyme deficiency, producing elevated adrenal androgens. Presents identically to PCOS. Diagnosed by elevated 17-hydroxyprogesterone. Must be excluded in every PCOS workup.
• Premature ovarian insufficiency (POI): Can present with irregular cycles but is distinguished by elevated FSH and low AMH — the opposite hormonal pattern from PCOS.
• Cushing's syndrome: Excess cortisol from pituitary or adrenal pathology can cause features resembling PCOS. Rare but should be considered if there are additional features (central obesity, striae, hypertension).
• Androgen-secreting tumours: Rare, but rapidly progressive virilisation (severe hirsutism appearing quickly, very high testosterone levels above 5 to 6 nmol/L) should prompt imaging to exclude a testosterone-secreting tumour.

The Minimum Diagnostic Investigation for PCOS

A proper PCOS diagnosis should include at minimum:

• Full menstrual history — cycle length, regularity, duration of any irregularity
• Clinical assessment of androgen features — acne location and severity, hirsutism (Ferriman-Gallwey score), scalp hair changes
• Day 2 to 3 blood panel: FSH, LH, oestradiol, total testosterone, DHEAS, prolactin, TSH
• 17-hydroxyprogesterone — to exclude NCCAH
• Fasting glucose and insulin (HOMA-IR)
• Transvaginal ultrasound — follicle count per ovary, ovarian volume, uterine assessment — ideally in the early follicular phase
• AMH — often elevated in PCOS, supports diagnosis

What Happens When PCOS Is Missed

When PCOS goes undiagnosed — particularly in lean women, women with subtle presentations, or women whose primary symptom is infertility rather than hirsutism or irregular periods — several consequences follow:

• Fertility delays: Women try naturally for years without ovulating regularly — losing time that is particularly precious after 35
• Endometrial risk: Chronic anovulation without hormonal protection of the endometrium — increasing the risk of hyperplasia over years
• Metabolic progression: Insulin resistance continues to accumulate towards diabetes without the lifestyle or medical interventions that would slow it
• Mental health impact: Unexplained symptoms and fertility struggles without a diagnosis are independently associated with anxiety and depression

Frequently Asked Questions

Q1. I was told I have PCOS because my ultrasound showed multiple follicles. Is this correct?

Not necessarily. Polycystic ovarian morphology on ultrasound alone is insufficient for a PCOS diagnosis. If your cycles are regular and you have no clinical or biochemical evidence of androgen excess, you may have polycystic-appearing ovaries without PCOS. Ask your doctor whether the Rotterdam criteria have been formally applied — and specifically whether the other two criteria (irregular cycles and androgen excess) have been assessed.

Q2. Can PCOS be confirmed without an ultrasound?

Yes — under the Rotterdam criteria, PCOS requires any two of three features. A woman with irregular cycles and elevated androgens has PCOS even if the ultrasound does not show polycystic morphology. The ultrasound supports the diagnosis but is not required when the other two criteria are clearly present. However, ultrasound provides valuable additional information (endometrial thickness, ovarian volume) and should be performed as part of a complete workup.

Q3. My periods are regular but I have acne and elevated testosterone. Do I have PCOS?

Possibly — this presentation (hyperandrogenism with polycystic morphology but preserved ovulation) corresponds to PCOS Phenotype C in the Rotterdam framework. Phenotype C has the mildest metabolic profile of the four PCOS phenotypes. If your ultrasound shows polycystic ovarian morphology and your testosterone is elevated, a PCOS diagnosis under Rotterdam criteria is supportable — but the clinical implications and treatment may differ from classic anovulatory PCOS.