优选目的:减少受术者痛苦和出血。优选范围:负压400—600mmHg 优选方法:瞎子爬山法。优选经过: 将负压瓶分别抽为400、500、600mmHg压力,分别妊娠子宫大小,选用不同压力经试验。结果为:40~+天孕用负压400mmHg,50~+天孕用负压500mmHg,60~+天孕,用负压 Preferred Objective: To reduce the suffering and bleeding of the subject. Preferred range: negative pressure 400-600mmHg Preferred method: blind hill-climbing method. Preferably after: the vacuum bottle were drawn to 400,500,600 mmHg pressure, respectively, the size of pregnant uterus, the choice of different pressures tested. The results are: 40 ~ + day pregnant with negative pressure 400mmHg, 50 ~ + day pregnant negative pressure 500mmHg, 60 ~ + day pregnant, with negative pressure