What is an Ovulation Predictor Kit (OPK)?

OPK stands for Ovulation Predictor Kit.

The OPK is a test that checks your urine for the presence of LH, luteinizing hormone. Normally, LH is in a steady state, at a low level (negative test). But when it rises very quickly (LH surge) it stimulates the developing egg (follicle) and ovulation (release of the egg) follows shortly thereafter. The OPK helps you predict when you are about to ovulate. Ovulation usually happens within 12-36 hours after the OPK first turns positive.
Read HERE MORE about OPKs.