System used to describe extended hysterectomy. Class 1, extrafascial hysterectomy only; class 2, resection of upper 1/3 of vagina and medial 1/2 of uterosacral and cardinal ligaments; class 3, resection of upper 1/3 of vagina and entire uterosacral and cardinal ligaments (for stage lb and 2a lesions); class 4, resection of upper 3/4 of vagina, tissue surrounding ureters, and superior vesical artery; class 5, resection of bladder and distal ureter.