Sunday, March 05, 2006

Panic-inducing, somewhat arbitrary, classifications

Sometimes, the phrase "high risk", it does not mean what you think it means.

Case in point: standard prenatal testing usually involves an ultrasound at 12 weeks that measures things like the nuchal translucency of the baby, plus a maternal blood test that looks at the levels of various hormones and proteins. Passing this data, plus the mother's age, through the diagnostic meat grinder results in a number that tells you the risk of the baby having Down's Syndrome. This number is generally conveyed to you by your doctor/ob-gyn/midwife/initiate-in-the-healing-arts-of-your-choice.

Now, here's the way you don't want that person to start the conversation: "I'm afraid that you're at high risk of having a child with Down's Syndrome." [which is how the conversation started for us]


That's the sound of our jaws and hearts hitting the floor. After the initial "Wha' happen ?" reaction, and a flurry of agitated questioning, it turned out that our kid apparently had a 1 in 130 chance of having Down's and the midwife suggested we go see a genetic counsellor to talk about what to do next. Needless to say, we were fixated on the "high risk" bit and dragged ourselves out of the door in a somewhat dejected manner.

About 30 minutes later, when my brain started working again, I realized "Wait a sec ... 1 in 130 ... that's less than 1% ... that's 0.8% ... that means the chances of the child not having Down's Syndrome are 99.2% ... sh!t, those are better chances than just about anything in life." Actually thinking about the numbers like that made us both breathe much easier.

It turns out that the phrase "high risk" means "greater than 1 in 250", and that cutoff is chosen because the risk of inducing a miscarriage by having amniocentesis, which can tell you for sure whether or not the child has Down's syndrome [as well as other chromosomal abnormalities] is about 1 in 250. In other words, the high-vrs-low risk classification is based on a cutoff that nobody without a screaming case of the OCD heebie-jeebies would consider "high risk", even taking into account the increased risk sensitivity induced by the thought of bringing a new person into the world.

You would think that part of the training given to people dealing with already on-edge parents-to-be would include helping them to see these sorts of diagnostic numbers in context. I mean, contrast a conversation that starts with

"Your child has a 99.2% chance of being OK, which is a bit lower than the 99.6% we usually like to see, so let's talk about what you might want to do"

with one that begins

"You're at high risk of having a child with Down's Syndrome."

It's hard to imagine a harsher start than the second one, other than maybe something like "Based on our tests, your child is doomed to a lifetime of pain and suffering -- an eagle will feast on his liver daily, he will be made to push a boulder uphill in perpetuity and, oh, let's see, it says here that ... every two days or so, he'll have to dive into a pile of razor blades, after which he'll be sprayed with salt dissolved in lemon juice. Any questions ?"

In any case, we opted to have amniocentesis to get rid of that niggling 0.8% of uncertainty and the child is fine and definitely a boy.

The moral of the story: when you hear a fuzzy phrase like "high risk", ask what the precise definition of that is before you get all wound around the axle.


Anonymous Keith said...

Wow that is definitely a top entrant for "Worst Bedside Manner." I guess that's why they call it practicing medicine.

Great news on the amniocentesis. I'm sure that was a huge relief of unnecessary, idiot-induced tension.

1:26 AM  
Blogger JoJo said...

Glad to hear that all is ok. Docs definitely need to go to some communication school not to mention stat classes. So excited for your guys!!!!!

11:17 PM  
Blogger Alex said...

Well, the screwy thing was that the person who told us this wasn't some fresh-faced kid out of med school -- it was a midwife with 20+ years of experience, and in general a very nice, personable woman.

8:48 AM  
Anonymous Ted said...

You did get me worried there for a sec! Glad to hear everything is just fine. I 100% agree w/ the moral of your story!

5:30 PM  
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