There are two things I want to say in answer to this question.
1) It would be very difficult to perforate with a flexible, 4mm cannula. If you held this cannula in one hand and attempted to punch it through your other palm, you would see that it bends back. Our uterine walls are made of thick muscles which would also bend back a narrow, flexible plastic cannula. We have no information or reason to think that a woman’s uterus has been perforated while doing menstrual extraction. We are very slow and careful, and the woman is awake and would alert us if she felt any pricking or cutting.
2) Sometimes perforation of the uterus can be a very serious complication of abortion. Nearly always a metal instrument has been used to “sound” the uterus, meaning to measure the depth of the uterus, or the uterine wall is thinner because the pregnancy is more advanced and the abortionist has vigorously inserted a thick and stiff cannula into the uterus.
But, even when perforation does occur, it probably will not be a problem unless the instrument has seriously perforated a blood vessel or intestine. Usually, as the uterus is emptied, it contracts and perforations are closed.
Dr. Michael Burnhill, a well-respected and experienced abortionist found out coincidentally many years ago about the frequency of perforations in abortions when he was performing tubal ligations. Ast is customar, he routinely suctioned out the contents of a woman’s uterus prior to tying her egg tubes to make sure that she wasn’t pregnant. Then, once in awhile, when he visualized the uterine wall using the laparascope, he saw signs of a closed-up perforation. He realized that simple perforations occurred more often than previously thought and he concluded that a simple perforation was not problematic. Dr. Burnhill published his findings.