Fruit of the Womb
Fruit of the Womb

Assessment of Fetal Lung Maturity - 1

On this site we have been firm advocates of preventing complications related to iatrogenic prematurity and, particularly, “late preterm births.” Indeed, in our own medical community, it appears the message has had a clear impact, particularly, over the past year or so since the American College of Obstetricians and Gynecologists has also come out in support of delaying elective deliveries (cesarean sections and inductions) until at least 39 weeks unless pulmonary lung maturity is first documented. Whereas in the past, I used to field phone calls on a daily basis from physicians requesting support to “induce Mrs. Jones at 37 weeks because her baby is huge and she is just miserable” or “her blood pressure may be creeping up and I am out of town next week, so I just thought I would do her repeat c/section tomorrow, what do you think?,” I now get phone calls for those sorts of indications, but accompanied by a request to perform an amniocentesis to assess fetal lung maturity.

However, some of the patients show up on our doorsteps either unclear about what “assessing fetal lung maturity” entails, or in denial of the same, or hoping, if they play dumb, I won’t figure out why they’re there. Unfortunately for them, I always ask, “What is your understanding of what your doctor would like us to do for you today?” Even if some of them have difficulty telling me that they are there to have an amniocentesis done, usually I will drag out of them that their doctor would like to “get me delivered.” That usually breaks down the barriers to discussing what an amniocentesis entails and the importance of assessing fetal lung maturity.

Some, honestly do not realize that “figuring out if the baby’s lungs have a reasonable chance of working well when they’re born” involves an invasive diagnostic study with a very long (but thin) needle. In fact there isn’t a day that goes by when we don’t have a patient ask, after we have done the preliminary ultrasound evaluation to determine fetal position, amniotic fluid volume, and placental location in preparation for the amniocentesis, “Well do the lungs look mature?” as they are sitting up and starting to clean off the ultrasound gel in premature preparation for leaving. When I then tell them that “we cannot determine that simply by looking” and start explaining what an amniocentesis is all about, and their eyes get as large as saucers and they start hyperventilating, it is clear they weren’t completely informed by their provider as to the nature of the evaluation. However, once they understand that their doctor does not plan to deliver them without that information, the discussion, again, becomes much more straightforward.

We have already discussed amniocentesis in other contexts and there is no reason to rehash the procedure or the risks associated with it, which are generally, quite small late in pregnancy. Instead, in our next post, I will discuss what it is we are looking for when we do fetal lung maturity testing and then we will describe some of the diagnostic tests currently available for that purpose…
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