Continuing the series of posts on the new International Society for Prenatal Diagnosis’s (ISPD) policy statement on prenatal testing for aneuploidy, I will seek to answer the questions prompted by that statement. In doing so, it leads to the ultimate question of whether the ISPD statement is unjustified?
In an earlier post, I asked whether the ISPD has its own version of Voldemort, i.e. is there something “which-must-not-be-named” in the new ISPD statement? This question was prompted by several statements that begged the question of “Why,” in the sense of, “what is the justification for that statement?” Examining those statements further shows the internal inconsistency of the ISPD statement:
- Aneuploidy risk assessment is a component of a broad set of prenatal clinical services that should be offered from 9-13 weeks gestational age whenever possible.
Why should they be offered at 9-13 weeks whenever possible when the ISPD statement says that testing at 12 weeks is optimal for first trimester (1T) testing?
- For women who come into care after the first trimester, risk assessment testing should be made available as soon as possible.
Why is this the case for second trimester (2T) testing when ISPD says 2T testing is optimal when performed between 15 and 19 weeks, not as soon as the 2T begins?
- First trimester aneuploidy screening (the ‘combined’ test) is more advantageous than second trimester screening (the ‘quadruple’ test) not only because information is available earlier in pregnancy but also because the screening has greater efficacy.
Why is earlier information better, particularly when ISPD’s statement recognizes that combining the results of 1T and 2T testing has the greatest efficacy for detecting aneuploidy in low-risk patients?
- Integrated screening can be offered when CVS is not available.
Why only when CVS is not available, given that amniocentesis has a lower rate of procedure-related miscarriages than CVS, making it safer, and integrated screening has a greater detection rate than 1T screening testing?
It seems clear that the unstated justification for all of these statements–the “Voldermort,” the “that-which-must-not-be-named”–is abortion. The only reason that compels, that justifies, offering testing as soon as diagnostic testing is available is to provide the maximum amount of time to have an abortion. What else justifies the ISPD statements that are counter to what the ISPD recognizes in the same statement to be optimal times and methods for prenatal testing?
I expect some readers will raise the point that prenatal testing can be justified for allowing expectant mothers to prepare for the birth of a child with Down syndrome. There are many personal stories that attest to this benefit and, at the ISPD conference last year in Miami, speakers and attendees mentioned “preparation” as a reason for prenatal testing, while “abortion” was hardly ever uttered.
The ISPD statement, however, is not based on the justification to allow a woman to prepare for the birth of a child with Down syndrome. If it were, it would not emphasize the need to test as soon as possible and only offer integrated screening when CVS is not available. Instead, if preparation were the only–or even the main–justification, ISPD’s recognized optimal prenatal testing protocol would be based on providing the information with the greatest detectability and lowest risk to the fetus.
The optimal preparation protocol would be integrated screening that combined NT testing at 12 weeks with quad testing performed between 15-19 weeks, followed by NIPS, and then confirmation by amniocentesis. This protocol provides the greatest detectability, lowest false-positives, the fewest number of pregnancies subjected to the risk of miscarriage with confirmatory diagnostic tests, and the safest diagnostic procedures with the lowest risk of procedure-related miscarriage. Finally, if preparation was the justification, then the ISPD statement would address third trimester (3T) prenatal testing, since a mother could still receive a prenatal diagnosis to prepare for the birth of her child.
The main reason for focusing on prenatal testing only up until the 2T, and disregarding 3T testing, is to allow a mother to abort following a prenatal diagnosis. The ISPD is silent on its reasons for finding one protocol for prenatal testing optimal versus another and why prenatal testing must be offered ASAP to every pregnant patient. You will not find abortion or termination mentioned in the ISPD statement, anywhere.
The silence of the ISPD begs the question of why it is silent about the central reason for its entire statement? Why does the ISPD refuse to name “that-which-must-not-be-named?”
We are left to wonder because of ISPD’s silence. Whenever there is an advance in prenatal testing for Down syndrome, ethicists and commentators call for a public discussion to determine how the testing should be ethically administered–indeed, this was called for by a platform speaker at this year’s ACMG conference. But, it’s very difficult to have that conversation, and to discuss what needs to be done for prenatal testing’s ethical administration, when those professional societies that set forth the optimal testing protocols refuse to talk about the reason for their position statements.
In the bioethics and legal world from which I come, when an argument lacks a justification, it fails. If you can’t explain the reason for your position, then your position is, by definition, unreasonable. Because the ISPD position statement is silent as to its justification, it is unjustified. Perhaps ISPD will provide clarification with an update or commentary that provides the reason for its position statement on prenatal testing for aneuploidy. Such a clarification is needed and would be welcomed if we are to be able to discuss honestly the reasons for prenatal testing for Down syndrome and how it should be ethically administered.
What do you think? Do you think the ISPD statement is unjustified? If not, please share where in the statement its justification is explained.