How PCOD is diagnosed: the Rotterdam criteria in plain words

If you are waiting for one clear test that says yes or no, here is the thing. There is no single test for PCOD. That surprises many women, and it explains why some are told one thing in one clinic and something else in another.

A doctor puts the picture together from your story, an examination, blood tests and a scan. That is a longer path than a thumb-prick, but it is a fairer one.

The Rotterdam criteria

Doctors use a set of rules called the Rotterdam criteria. There are three signs, and you need any 2 of the 3. Other conditions that can look similar must be ruled out first.

Irregular periods or no ovulation

Typical cycles run 21 to 35 days. Cycles longer than 35 days, fewer than 8 periods a year, or skipping months suggest that ovulation is not happening regularly. Ovulation is what the monthly cycle is built around, so when it is irregular or absent, periods show it.

High androgens

Androgens are hormones every woman makes in small amounts. Higher levels can show on the skin and hair, as acne on the jawline and chin, coarse dark hair on the upper lip, chin, chest or belly, or thinning at the parting. They can also show in blood tests, such as free testosterone, SHBG or DHEA-S. Doctors can use either the signs or the blood tests.

Polycystic ovaries on a scan

A pelvic ultrasound can show many small follicles in the ovary. These are stalled egg sacs, not harmful cysts. They do not turn into cancer and usually do not need surgery.

Why only 2 of 3 are needed

PCOD does not look the same in every woman. One woman has irregular periods and acne, with an ovary that looks quite ordinary on the scan. Another has the scan finding and high androgens, but regular periods. Because the picture varies, doctors do not insist on all three.

It also explains a common myth. Regular periods do not mean no PCOD. You can have PCOD with regular periods, and tests tell.

Ruling out other conditions

Thyroid and prolactin problems can look like PCOD. They can also cause irregular periods and hair changes. So both are always tested. Other causes of tiredness, weight change or hair fall, such as low iron, low vitamin D or vitamin B12, are checked at the same time. Your doctor may rule out a few rarer causes of high androgens too. A sudden deepening of the voice with rapid hair growth is not typical PCOD, and needs urgent care.

Tests you may be advised

Your doctor chooses only what suits you. The usual groups are hormones, sugar, heart health, vitamins, a scan, and body measurements such as weight, waist and body composition. One separate article explains each test, and another covers the scan.

Sugar tests have a reason in a diagnosis, even though they are not part of the Rotterdam rules. Insulin resistance is common in PCOD, and it affects the treatment plan. So doctors may check fasting sugar, insulin, HbA1c and sometimes an OGTT or HOMA-IR.

A special note for teenagers

A scan alone is not used to diagnose PCOD in the first 8 years after periods start. Teen ovaries often look polycystic on a scan, and irregular periods are common in the first 2 to 3 years because the body is settling in. A doctor looks at the whole picture and may wait and watch. It is not a reason to panic, and it is not a reason to ignore it either. See a doctor if there is no period by age 15, or more than 3 years after breast growth began.

Where you sit on the spectrum

Names can confuse. PCOM means small follicles seen on a scan only, with no hormone problem. PCOD is a mild hormone and cell imbalance. PCOS is a more complex, whole-body hormone and metabolic condition, and PMOS is the new official name for PCOS. Doctors now see these as steps on one spectrum. Your doctor decides where you are after your history, tests and scan, and the plan follows from that.

How to get ready for your appointment

You can do a lot before you walk in.

• Write the first day of every period for the last few months.
• Note weight changes, acne, hair growth and hair fall.
• List medicines and supplements you take.
• Bring old reports, scans and blood tests.
• Write down your questions. Good ones include: What type of PCOD do I have? Which tests do I need, and how often? What are my goals for the next 3 months? When should I plan a pregnancy?

Get help urgently if

Severe lower tummy pain, fainting, very heavy bleeding, chest pain or breathlessness, or a sudden deepening of the voice with rapid hair growth, needs a doctor straight away.

This article is education, not a diagnosis. Only a doctor, after your history, examination and tests, can decide whether you have PCOD, PCOS or PMOS.