The clinical grading standard for pituitary tumors is now the Hardy-Wilson grading method. This grading method is based on the relationship between the pituitary tumor and the surrounding tissues, and is generally divided into five grades: Grade I is when the pituitary tumor is within 10 mm in diameter and all of the pituitary tumor is located in the saddle. Grade II refers to a pituitary tumor that extends superiorly to the saddle, reaching 10 mm and filling the structures of the suprasellar pool. Grade III refers to a pituitary tumor that grows suprasellar to about 10-20 mm and affects the third ventricle. Grade IV refers to a pituitary tumor that expands suprasellarly to 20-30 mm and fills all of the anterior part of the third ventricle. Grade V means that the pituitary tumor extends more than 30 mm and reaches the interventricular foramen of the lateral ventricles.