This is the third installment of Chapter 2’s dive into exploring prenatal genetic testing. The earlier installments can be found here. Read on and see if you think the title of this post is accurate.
Professional guidelines and position statements become cited in medical malpractice lawsuits if the practitioner failed to follow them. By failing to adhere to what are labeled “guidelines” and “recommendations,” these statements cease being permissive suggestions that practitioners can consider when treating their patient. Essentially upon issuance, they are obligatory standards of care, which by definition means malpractice if not followed. Like the old advertisement tagline used to say, when ACOG speaks, OBs (and plaintiff’s lawyers) listen. And, this is indeed the intent of ACOG in issuing its guidelines (as well as the National Society of Genetic Counselors (NSGC) and ACMG). ACOG does not go through the process of surveying the published studies, classifying them by quality of research done, then synthesizing them into existing statements with the point of no one paying attention to them. Practice guidelines and position statements are issued so as to change clinical care, and, no doubt, change it for the better in the eyes of ACOG’s then governing board of directors (who finally approve all practice bulletins).
Specific to the revised guideline on prenatal testing, ACOG bookended 2007 with two practice bulletins saying all women should be offered diagnostic testing. The first was Practice Bulletin No. 77, issued at the beginning of 2007, which focused on prenatal screening, but began by recommending all women be offered prenatal diagnostic testing. In case the revision was missed by practitioners, ACOG then issued online in December of 2007 (and ultimately published in 2008), Practice Bulletin No. 88. PB 88 had as its focus exclusively prenatal diagnostic testing and, again, reminded practitioners to offer prenatal diagnostic testing to all women.
ACOG achieved its purpose in issuing its revised practice guidelines, with practitioners changing their behavior and offering all women prenatal testing. Here’s the thing, though: the reasons for changing the guidelines only applied in two health systems.
ACOG PB 77 and PB 88’s recommendation for all women to be offered prenatal diagnostic testing was premised on studies reporting a lower risk of miscarriage for CVS and amnio. Those studies, however, were from just two health systems, one in California and one hospital in St. Louis, Missouri. Recall, that the lower rate of miscarriage was tied to the experience level of the practitioner and the facility where the procedure was performed. This is really just a matter of common sense: it is not shocking that where someone does something in a place that does that same thing a lot, they get better at it. But, the converse then is equally true: where an OB or maternal-fetal medicine specialist (MFM) does not have the same amount of experience with amnio or CVS and performs those procedures at a facility that does not do the same volume as the health system in California or in St. Louis, then, odds are, they will have a rate of miscarriage higher than what ACOG relied upon. Indeed, that rate of miscarriage could be as high or higher than the traditionally quoted 1% for amnio and 2% for CVS. Yet, on the basis of two studies, ACOG imposed a national standard of care and those expectant mothers having an amnio or CVS in 49 other states and dozens of other major metropolitan areas, well, their risk for miscarriage is unknown. This becomes even more concerning when considering the impact of prenatal genetic screening in the next section of this chapter.
Advances have been made in the amount of information prenatal diagnostic testing can report. When tests were developed, the karyotype was primarily the lab report that would be done. A karyotype provides a visual representation of the number of chromosomes present. In 2008, I attended my first ACOG Annual Clinical Meeting (ACM), which was held in the McCormick Center in Chicago, Illinois. Just beginning my investigation into the world of prenatal testing and having an almost four-year old daughter, I wondered, “why are we testing for Down syndrome?” I wondered this because at this conference labs like the one at Baylor were highlighting how prenatal diagnostic testing had advanced and could test for micro-deletion conditions, where a genetic section was missing from a chromosome, and dozens and dozens of other conditions. Why, then, was Down syndrome considered the shorthand for prenatal testing?
I approached a representative at the exhibit booth for Sequenom, a company that would ultimately become the first to go to market with cell free DNA screening and establish market dominance. I asked her my question of “Why is there prenatal testing for Down syndrome?” Without batting an eye, she succinctly replied, “because it’s easy. All you have to do is count past 46 and odds are you’ve found Down syndrome.” As will be explained further in the chapter devoted to Down syndrome, its genetic cause is an extra chromosome. What the Sequenom rep was saying is that for most people they have 46 chromosomes. So, if you found a 47th, odds are you had identified Down syndrome, the most commonly occurring condition with an extra chromosome.
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