Are You Making I&D Incisions Correctly?

I’m more familiar than I would like to be with I&Ding abscesses. As a nurse practitioner working in the emergency department, it’s pretty much part of my day-to-day. Whether you’re in family practice, ER, urgent care or even some specialties, chances are you do your fair share of office procedures as well. While most nurse practitioners learn these procedures in school, I do find that many haven’t been trained in some of the finer details of performing them correctly. One such point involves I&Ding in a way that maximizes the probability of a favorable cosmetic outcome. Did you know that there’s a correct or suggested orientation by which you should make incisions?

When you look at an abscess, your mind likely goes straight to just getting the thing open. There’s nothing more gratifying than releasing a load of pus from a nasty, fluctuant abscess. But, before you wield your scalpel, step back and take a look at the area. Randomly placing that scalpel point and making a cut that’s vertical or horizontal on a whim isn’t your best course of action. Rather, whenever possible, you should make incisions parallel to natural skin tension lines. Cutting perpendicular to skin tension lines is more likely to lead to noticeable scarring and complications like keloids. 

Example: Flex your wrist and check out the creases created on the ventral surface of your forearm (just proximal to the palm of your hand). The creases run horizontally across your forearm. Making an incision parallel to, or in line with, these creases is much less likely to create a noticeable scar than an incision moving vertically or perpendicular to these creases. 

Understanding Skin Tension Lines

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Some skin tension lines are obvious by looking at the patient (as in the above example), but others are not. It’s best to look at a diagram to help understand where these natural lines lie. There are a number of smart individuals who have proposed systems for looking at skin tension lines. Here’s a snapshot of a few of these methods for identifying the best place to cut. 

Langer Lines 

In 1861 Austrian anatomist Karl Langer first described such tension lines on the body that correspond to the orientation of collagen in the dermis. Historically, these lines have been used to determine the optimal incision line. Cutting parallel to Langer lines leads to better healing and less scarring than cutting across them (i.e. perpendicular). Cutting perpendicular to these lines leads to a more obvious wound and results in puckering when the wound heals. 

Kraissl’s Lines and Borges Lines

While Langer’s work was valuable and serves as a guide for providers making decisions, his theory has been improved upon. Langer’s research on skin tension lines was done on cadavers. Anatomical skin lines on living human beings are a bit different. 

Kraissl discovered that wrinkles occur perpendicular to underlying muscle action and drafted his own map of skin tension lines. Borges is credited with describing relaxed skin tension lines. Essentially, these are the furrows we see when skin is relaxed. They are more prominent when pinching the skin and examining the direction of furrows and ridges. 

Because Kraissl and Borges did their work by studying living subjects rather than cadavers, they are generally credited with developing better models to follow when choosing your incision direction (though in many cases they are the same or similar to Langer’s lines). Simply look up a diagram for “skin tension lines” and cut parallel to these lines the next time you I&D an abscess for the best possible cosmetic outcome. (Note: The same philosophy can also be used for biopsy and other elective procedure incisions) 


Was this a helpful clinical tip? Ask your employer about enrollment in our ThriveAP program designed to help less experienced nurse practitioners up their clinical game. We hope to see you in our upcoming April 2019 cohort. 


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