In the first place, it is not a "seal" but already includes space for the release of secretion or blood. Second, for most women the hymen is fragile and can be easily broken in activities from sex to use of sanitary napkins to riding a bicycle.
有些女性的處女膜堅韌得必須請婦產科醫生開刀才能破裂；大多數則很容易破裂﹘﹘性行為、使用衛生棉條、騎腳踏車、騎馬或其他激烈運動，都可能使處女膜破裂。