In medical school, students learn to note a patient’s appearance and clothing (words like “disheveled” or “well-groomed” seem to pop up a lot in the medical record). They’re taught to interpret the patient’s gestures and eye contact, or lack of it, and to think about their own body language. And yet, somehow, the topic of doctors’ own clothing rarely comes up, save for the most flagrant lapses (plunging necklines, jeans, T-shirts) or the simple and vague admonition to appear “professional.”

“Professional” is a tricky word in a clothing context. It’s possible, of course, that other patients found the stiletto doctor’s business attire entirely appropriate, a reassuring hat-tip to the doctor’s traditional stature. In days of yore, the doctor was clearly identifiable by the white lab coat over shirt and tie, his agreeable nurse counterpart unmistakable in white dress and cap (which, depending on one’s school, might be shaped like a coffee filter, sailor’s cap, or a hamantaschen). But in the 21st century, especially in primary-care medicine, much has changed; with more categories of clinicians (nurse practitioners, physician assistants) in every sphere of medicine, the traditional clinical clothing boundaries have blurred.

The definition of what counts as professional clothing is also in flux, thanks to increasing knowledge of infectious risks. Earlier this year, the Society for Healthcare Epidemiology Association (SHEA) published new guidelines for healthcare-personnel attire in hospital settings. Their goal was to balance the need for professional appearance with the obligation to minimize potential germ transmission via clothing and other doodads like ID badges and jewelry and neckties that might touch body parts or bodily fluids. The SHEA investigators' take-home points regarding infection: White coats should be washed weekly, at the minimum; neckties should be clipped in place (70 percent of doctors in two studies admitted to having never had a tie cleaned); and institutions should strongly consider a “bare below the elbow” (BBE) policy, meaning short sleeves and no wristwatches or jewelry. Although the impact on reducing the risk of infections remains to be determined, it’s considered potentially significant enough that a number of countries have adopted BBE requirements for all clinicians. (And it leaves me wondering: When will the Mayo clinic update its dress code to short-sleeved business suits?)

The report also addressed the question of what patients want their doctors to wear. The short answer from the SHEA investigators, who reviewed 26 studies of patient perceptions of doctors’ clothing, was that patients prefer that doctors appear “formal” rather than “casual.” But forcing all clothing-description categories into one or the other of those two somewhat vague terms is misleading. Here’s why: In those studies (including one that was satire and shouldn’t have been included), there were abundant ways of describing clothing with so many different scales and definitions of formal versus casual it would make your head spin. Consider a few of the many systems for categorizing outfits: A man’s shirt and tie was “formal” in one study, “semiformal” in another, and elsewhere “business” and “professional informal.” A woman’s dress or skirt was “formal” in one, “business” in another. Slacks and a pullover shirt or blouse: “casual” in one, “smart casual” in another.