That is usually so Emma but not always..

A positive opk says that the LH surge has occured. However you can have a surge but an egg is not released - so we don't ovulate. It is quite usual for women to have the occassional annovulatory cycle...

Also, a woman's body can gear up to surge and then not.

Women that have pcos have a higher level of LH in their bodies normally so some of these women will report that they have quite a prominent second line many times throughout their cycle. OPK's can sometimes be tricky for women with PCOS. It can depend on what brand of opk's you use. Some opk's will pick up a lower level of LH than others so therefore you will get a second line more easily - iykwim...

The only way of determining with a fair degree of accuracy weather ovulation has occured is by having a 7dpo progesterone level taken... Or of course by conceiving!!!

That is why it is difficult for women like me who don't get a positive opk (without copious amounts of testing and using LOTS of strips!!!) because the second line could be just picking up LH which is always floating about to varying degrees. If I use an opk just after AF on urine that I have held for 5 hours (I have done this as an experiment!) I will get a second line. If I use LH strips on fMU close to surge time I will also get a close to positive. I haven't got PCOS.

If you do get a positive opk you can be fairly sure you are about to ovulate. However as I said you can surge but not release an egg!

However, if you don't usually have two lines and then you find you do, it is likely that you are about to surge and then ovulate. The only way of knowing with a fair degree of certainty is by the 7 dpo progesterone level...

Just an aside Emma congratulations on growing a baby girl! Gorgeous name! Your ticker is really flying... I hope you are well...

Hugs