This method has been proposed for cases in which there is suspicion that the layer surrounding the ovum, called the zona pellucida, has hardened, which results in the fertilised ovum not being able to ‘hatch’ through this ‘shell’ in order to implant into the uterine wall. Studies have shown that application on the general population improves the chance of success, and, therefore, this method is applied in selected cases in which there are indications of hardening of the zona pellucida.
