Yes. The RCOG states that in up to 1% of all cases pregnancy continues after the woman has taken the abortion pills and that in up 6% of all cases the abortion is incomplete; another procedure is required to correct both types of treatment failure. That said, some only consider ‘failure’ to include the first one of these.
To answer this question, we first need to understand how medical abortion works. MSI Reproductive Choices (MSI-RC) provides the following information in its abortion care booklet, ‘Your Choice, Our Support’, available on this webpage:
“Medical abortion (abortion tablets) involves taking two sets of tablets to end a pregnancy. There are two different medicines used. The first is called mifepristone. It stops the pregnancy from growing by blocking the hormone progesterone, and causes separation of the pregnancy from the wall of the womb. The second medication is called misoprostol. It causes the softening and opening of the cervix (neck of the womb) and contractions of the womb so that the pregnancy passes through the vagina.
In the above, the term ‘pregnancy’ is being used to define the developing embryo and placenta.
So, medical abortion involves two steps, and for it to be successful (ie not fail) both steps must be completed. There are two possible failures: first a failure in which the woman remains pregnant and the embryo is continuing to develop, and secondly when the tablets fail to cause the embryo and/or placenta to be fully passed out of the woman’s body.
Linepharma is the manufacturer of the mifepristone used by MSI-RC, and in its summary of product characteristics (SmPC), the document used to inform healthcare professionals about use of the drug, it states:
“The non-negligible risk of failure, which occurs in up to 7.6% of the cases, makes the control visit mandatory in order to check that the expulsion is completed.
It is clear that Linepharma considers failure of its drug to include incomplete expulsion. The complications arising from this medical treatment failure include retained products of conception (RPOC) and is termed an incomplete abortion.
Ranbaxy, the manufacturer of Medabon, the mifepristone used by BPAS, states in its SmPC:
“The non-negligible risk of failure, which occurs in 4.5 to 7.8% of the cases, makes the follow-up visit mandatory in order to check that abortion is complete. The patient should be informed that surgical treatment may be required to achieve complete abortion.
It too considers an incomplete abortion to be a treatment failure; the surgical treatment mentioned is an evacuation of retained products of conception (ERPC). Ranbaxy includes data from clinical trials performed by the WHO, showing data for both an incomplete abortion and continuing pregnancy, the latter occurring in 0.9% of cases.
The Royal College of Obstetricians and Gynaecologists (RCOG) takes a different approach when detailing these rates. It only considers ‘continuing pregnancy’ as a failure, occurring in fewer than 1 in 100 women. It refers to an incomplete abortion as a complication, stating “The uterus may not be completely emptied of its contents and further treatment may be needed. This happens in fewer than 6 in 100 women having a medical abortion.”
The ‘complication’ detailed by RCOG is the same as the ‘non-negligible risk of failure’ detailed by both manufacturers.
So, does it matter if we are calling these failures or complications? There are some who might choose to use the RCOG definition of failure, claiming that the success rate for medical abortion is over 99%. But surely, this minimises the risks. For clarity, and to show that we are not conflating failure and complications, we choose to follow the approach taken by the abortion pill manufacturers and consider both a continuing pregnancy and an incomplete abortion as medical treatment failures.
What really matters is that women are told that there is a 6%, 1-in-17, risk that the abortion pills will not work correctly, that after taking these, she might still be pregnant or she may have retained products of conception, and when this happens she will need to seek medical attention.
You can read more about this in an earlier post ‘The Abortion Pill is not always effective.’ or in other posts listed on the Abortion Complications page.
Percuity 