Routine ultrasound for presentation at term

A reader left a comment on my Surprise Breech post suggesting that we might have used ultrasound prenatally in order to prevent the surprise. It's a bit snarky for my taste, but here it is, followed by my response (which I didn't include in comments on that piece):

"lisa said... Ahem: an ultrasound or two might have been a good idea? Just sayin'....this isn't the Dark Ages. We have modern medicine now."


We love modern medicine! We're so thankful that it exists when we need it. And in fact, if we'd had the slightest question in our minds about this baby being head down or not, we would have referred her to an ultrasonographer. We use ultrasound as necessary, just like we access every other medical intervention as necessary.

Actually, standard of care in modern medicine includes an ultrasound at around 20 weeks, so early that babies are still swimming around in utero, and their position is inconsequential. Most obstetricians still use their hands to assess fetal presentation at term. (Most do a vaginal exam to feel for baby's head.) So, even current medical standards don't include your suggestion.

That said, the tides are turning. More and more obstetric practices are not touching women at all, using ultrasound at every visit to assess fetal growth, and to assess fetal presentation at term. Some hospitals are indeed doing an ultrasound on each woman in labor to check that the baby is vertex. Serial ultrasounds, in fact routine ultrasounds of any type, are not recommended in pregnancy even by the professional organizations that you might think would recommend them. Feel free to google for guidelines, and you will see that each notes that ultrasound is to be used as medically indicated. The FDA advocates for the "prudent use" of ultrasound. Unfortunately, many practitioners misconstrue the vague guidelines about what constitutes necessity; for example, the guideline to use ultrasound to assess fetal growth has been perverted to mean it should be used at every visit rather than in the instance that a concern about fetal growth has arisen in other medical assessments. (Just because I love metaphors: I don't need my children to get an MRI at every well-baby visit; measuring head circumference will do.)

Is this safe? What untoward effects might serial ultrasound have? We really don't know. We know babies aren't being born with missing fingers or with severe mental retardation. But, we haven't studied it well enough to know what less obvious effects might be occurring. We do know that ultrasound changes cells - and I am going to go out on a limb here and say that since fetal cells are generally normal, to say that ultrasound changes them is to say that ultrasound damages them. Several studies have shown an increase in left-handedness in children who were exposed to ultrasound in utero. Who cares about left-handedness, you might say... but what this study tells us is that ultrasound changes the fetal brain. Anecdotally - and I'm not a fan of anecdotal evidence, but in this instance it's pretty striking - over half of the children I know personally who had serial ultrasounds in utero have significant issues that affect their lives, including hearing loss, behavioral issues, and learning disabilities.

So, should our practice adopt a policy of routine ultrasounds at the end of pregnancy to catch breeches? Let's apply some math. (Yes, I'm a geek, it should be well established.) This was my preceptor's first surprise breech in her career of over 450 births. According to the flawed study that all but ended vaginal breech birth in the United States, which I will quote here since it is the standard quoted study despite its flaws, planned vaginal breech birth carries a 5% incidence of perinatal mortality or serious neonatal morbidity, or an incidence of 1 in 20 of any undesirable outcome including those that can be overcome with time. 20 x 450 = 9000, so there is a 1 in 9000 chance of anything at all bad happening, even something temporarily bad as opposed to death or permanent disability, because we don't diagnose fetal presentation with ultrasound. A 2009 study found that there was a 0.2% incidence of perinatal death for breeches, so 1 in 450 x 500 = a 1 in 225,000 chance of a baby dying because we didn't do an ultrasound for presentation at term. Compare that to asking every one of those 225,000 women and babies to expose themselves to the unknown risks of ultrasound, the known evidence around ultrasound radiation, and the costs - well, let's not even discuss money here - the answer is no. No, I don't see us recommending an ultrasound or two at term for all our mamas and babies.

I haven't even touched upon the most important issue. The hallmark of midwifery care is client-centered care. We offer our clients information and they make their own decisions. The potential for an unanticipated malpresentation is in our informed consent to home birth. If a client desired an ultrasound at term for presentation, we'd discuss all of the above and then respect their decision.