Why does incomplete abortion occur?

Incomplete abortion means that the embryonic sac or placental tissue is not completely sucked out during artificial abortion, and there are residual embryonic tissues in the uterine cavity. These tissues are either free in the uterine cavity or still attached to the uterine wall, resulting in excessive bleeding and prolonged bleeding in the operating room or after surgery. The possible causes of incomplete abortion are:

① The surgeon is not skilled and has an inaccurate grasp of the size and position of the uterus. He or she has no sense of whether the uterine cavity has been vacuumed or scraped clean, which can easily result in part of the embryo or chorionic tissue not being vacuumed or scraped clean.

② Uterine malformations such as uterine septate, didelphys, saddle-shaped uterus, and bicornuate uterus are difficult to operate on and may sometimes result in incomplete abortion.

③ Uterine fibroids complicated with pregnancy, especially submucosal fibroids, cause irregular uterine cavity and make surgical operation difficult.

④ The implantation position of the fertilized egg is special, such as at the bottom of the uterine cavity, which is not easy to be fully reached by the straw and scraper.

⑤ The negative pressure is too high, which stimulates the uterine muscle wall to undergo irregular contractions and forms a narrow ring in a certain part of the uterine cavity, causing tissue damage.

⑥ The negative pressure is too low, the rubber tube is too soft, and the straw is too thin, resulting in insufficient suction. This will not only easily lead to prolonged operation time and increased bleeding, but also easily cause incomplete abortion.

⑦ The operation was not performed according to the routine steps. Before the end of the operation, the scraping was not carefully checked to see if it was completely clean, especially the uterine angles on both sides. The scraping was not checked to see if it was complete and whether it was consistent with the month of pregnancy. Incomplete abortion can be manifested as excessive uterine bleeding during or after the operation, and the duration is prolonged. Sometimes poor uterine involution may be found, and sometimes necrotic placental tissue may or may not be seen when the cervix is ​​opened. The radioimmunoassay of human chorionic gonadotropin in the dish did not drop to normal levels 3 weeks after the operation.