Spinnbarkeit phenomenon is :

At the time of ovulation, the cervical mucus is thin and profuse that the patient may notice a clear discharge, the so-called normal ovulation cascade. This ovulation mucus has the propey of great elasticity and will withstand stretching up to 10 cm. This phenomenon is called spinnbarkeit or the thread test for oestrogen activity. During the secretory phase, the cervical mucus becomes tenacious and its viscosity increases under the influence of progesterone so that it loses the propey of spinnbarkeit and fractures when put under tension. This propey is called tack. THIS LOSS OF SPINNBARKEIT EFFECT IS USED TO DIAGNOSE OVULATION RETROSPECTIVELY.