Evidence-Less Medicine

"The practice of medicine is an art, not a trade; a calling, not a business; a calling in which your heart will be exercised equally with your head."
-William Osler

It's common to hear physicians say that medicine is an art and not a science.  In spite of evidence-based medicine (EBM) being all the rage these days, a whole lot of what we do is based on expert opinion, what we think should theoretically work, anecdotal experience, and unabashed personal preference.  Most laymen don't realize just how unscientific medicine really is, and sometimes that leads to a huge disconnect between patient expectations and physician expectations.

I struggled with a great example of this phenomenon while on my OB rotation.  During the first stage of labor, the mother's cervix dilates from somewhere between 0-2 cm up to 10 centimeters.  This is a process that takes several hours, and sometimes even a day or two.  As you might expect from the name, being in labor for so many hours is exhausting for the patients, both physically and emotionally.  It also gets more painful as the fetus descends lower into the mother's pelvis and the contractions get stronger.  Most of the patients understandably want to be reassured that things are progressing well and that there is an end in sight.  The way we assess labor progress is by performing cervical checks on a scheduled basis.

To perform a labor check, the examiner (generally a resident, attending, or nurse) puts on sterile gloves and inserts two fingers into the patient's vagina.  The examiner then measures the width of the cervical opening based on how far he or she can spread the two fingers apart.  This is a highly subjective and imprecise process.  We don't all have fingers that are the same size, and it's not uncommon for two experienced examiners to differ by up to a centimeter in their measurements, especially when the cervix is over halfway dilated.  Throw an inexperienced examiner like me in the mix, and the lack of precision becomes even greater.

Because of this imprecision, we sometimes ran into a situation where the second examiner told the patient that she was less dilated than the previous examiner said.  The patients would understandably get very upset by this, as it seemed to imply that not only was their labor not progressing, but it was even going backward.  After the first time I accidentally did this to a patient, I always asked the patient how far the previous examiner had said she was dilated before I did my exam, and I never said she was less dilated than that.  Sometimes I'd tell the patient that her cervix was a centimeter more dilated than what the previous examiner had said, even though I wasn't totally sure if it had actually changed.

The problem was that many patients thought our labor checks were precise measurements of cervical dilation.  But the more dilated the patient's cervix got, the harder it became to know what the actual measurement was.  As I already said, even experienced examiners can differ by a centimeter or so in the later part of Stage 1 labor, and I was sometimes off by two or three centimeters.  I didn't want to give a patient the wrong impression that her cervix was contracting instead of dilating.  To add to the confusion, sometimes the size of the cervical opening really did change during the period of time between two examinations.  And even if I had wanted to explain why examiner #2 gave a smaller measurement than examiner #1, a woman in active labor is not usually up for having a philosophical discussion about why different examiners might tell her different numbers.

I never really learned the finer points of cervical measurement late in the first stage of labor, and it ultimately doesn't matter to me if a patient's cervical dilation is eight centimeters versus nine centimeters anyway.  I realized partway through the rotation that what I really need to know as an emergency physician is how imminent the delivery is.  If I do my exam and find that the cervix is only partially dilated, that means I probably have enough time to get the patient up to the L&D floor before she delivers.  But if I feel caput and hair, that means I'd better gown and glove up pronto.  Telling partially dilated cervix apart from caput and hair is very easy and completely objective.  There is no such thing as a hairy cervix!