Skin abscesses are quite common in correctional facilities, especially in the MRSA era, and so all correctional practitioners need to be comfortable with the procedure of abscess incision and drainage, also known as “lancing” the abscess.  Also “Let’s cut that sucker open.”  However, I’m going to be professional and call this procedure “I&D” for “Incision and Drainage.”

When I was just starting out in emergency medicine, I&D seemed to be quite a daunting task.  I was afraid of making a mistake and hurting someone or making them worse.  However, in actual fact, I&D is quite easy.  You can potentially hurt people more by not doing an I&D than by doing one.

But, like all medical procedures, it is possible to do the procedure poorly and inefficiently or to make outright mistakes.  The subject of today’s post is how to do a simple I&D of a skin abscess.  The opportunity to take pictures of the procedure arose when a fireman friend of mine walked in to my office and asked me to look at a lump on his back that had been there for a few days.  It was quite sore.  Here is a picture of the lump:

This appears to me to be a MRSA abscess.  Statistically, MRSA causes approximately 75% of all community acquired skin abscesses.  But beyond the statistical likelihood, this looks like a MRSA abscess.  It has lots of pus for its size along with a central area where the lesion is “pointing.”  This appearance is commonly mistaken for a “spider bite” by the lay public.

Why did my friend get a MRSA lesion on his back?  I don’t know.  Why does one member of a family get strep throat but not the others?  It just happens.  Usually, the only way to pinpoint the source is when multiple patients with a common background get MRSA, like members of a wrestling team or inmates housed in the same dorm.  A single, isolated case like this just happens—and not infrequently.

The treatment for MRSA abscess is Incision and Drainage, so I am going to cut this sucker open to let it drain—oops!  I mean I am going to perform an I&D procedure and document the process with pictures and discuss each step.  The process of I&D consists of these steps:

1.  Skin cleaning.  I did this using alcohol wipes.  It is important to remember that this is not a sterile procedure—even if you do a surgically prep and drape the skin and use sterile gloves, they will not remain sterile once everything is covered by pus from the abscess!  Instead, this is a clean procedure.  You want everything to be clean, but you do not have to perform a formal surgical prep.
2. Anesthesia.  I prefer to use 0.25% bupivicaine (Marcaine) with epinephrine.  Why Marcaine instead of lidocaine?  Well, they are comparable in price and Marcaine has the advantage of lasting 3-4 times longer, so the area stays numb for 12-16 hours instead of 4 hours.  Why use epinephrine?  The main reason to use epinephrine is that it constricts skin blood vessels so there is much less bleeding.  This makes the procedure that much easier to perform.  Epi also makes the anesthesia last longer—another bonus for the patient!
3. Make the incision.  I prefer to use a #15 blade scalpel rather than the traditional #11 blade—but either will work.  The most common mistake made when incising an abscess is not to make the incision big enough.  The incision needs to be long enough and deep enough to allow access to the abscess cavity later, when you explore the abscess cavity.  Note that my incision stretches the whole diameter of the abscess—all the way from the top edge of redness to the bottom edge of redness.  Notice also that I have chosen in this case to make the incision run across the lines of tension of the skin by incising from top to bottom.  Typically, you would make an incision run the same direction as the skin creases if you want to minimize the scar.  I don’t care too much about a scar in this case, since the lesion is on the patient’s back.  I am more concerned with adequate drainage of the wound.  By making the incision perpendicular to the creases, the skin will naturally gape open after the procedure and allow pus to drain.  Not allowing the skin edges to touch and potentially re-seal is also the reason for placing packing in the wound, which we will discuss later.
4. Squeeze out the pus.  This abscess had quite a bit of pus.  By the way, you do not have to routinely send this pus for culture in the majority of young healthy patients, especially if you are not going to prescribe an antibiotic (discussed later).  Culture is a good idea in complicated cases, such as immunocompromised patients, or large complicated abscesses.
5. Explore the abscess cavity.  There are several reasons to do this.  The first is to see how deep the abscess goes.  Some abscesses are like icebergs—what you see at the surface is only a small portion of the whole abscess.  Some can run amazingly deep.  You should find the full extent of the abscess cavity.  Second, many abscesses have multiple chambers and your incision may have only drained one.  By exploring the cavity, you will break any remaining abscess walls and make sure the entire abscess has drained.  Finally, many abscesses have thick, adherent pus stuck to the walls that does not drain easily.  By rubbing the inner walls of the abscess, you will loosen that thick pus and get it out.  How to explore the abscess cavity depends on the abscess size. I have found that the best instrument for exploring bigger abscess is my gloved finger, as I have done here (as long as you are sure there are no foreign bodies in the abscess).  I have seen surgeons get their whole hand inside really big abscesses (of course abscesses that big probably should be sent to a surgeon).  On the other hand, you may not be able to get your finger into a small abscess.  A curved mosquito forceps with some gauze at the tip works well in those cases.
6. Irrigate the interior of the abscess with saline.  This is done to make sure that we have all of the pus out.  When the saline draining out of the abscess is clear, the abscess cavity is clean.
7. Insert a pack.  Abscess packing is perhaps the single most misunderstood aspect of abscess I&D.  The purpose of the packing is to prevent the skin edges from re-sealing.  It is a mistake to think that the packing aids healing.  It does not.  There needs to be enough packing in the interior of the abscess cavity to prevent the wick from falling out, but there is no benefit to stuffing a ton of packing into the abscess.  In fact, that is detrimental, because the packing is a foreign body and because if the packing is packed so tightly so as to exert pressure, it can cause tissue necrosis.  In fact, not every abscess needs to be packed.  If the opening is gaping so widely that there is little chance of the edges re-sealing together, there may be no need for packing.  This point is so important that I will say it again:  abscess packing material is a foreign body.  It can delay healing and resolution of the abscess.  Its only function is to prevent the skin edges from re-sealing. The packing I place today will be removed tomorrow.  I don’t want it in there very long.  It is a foreign body.
8. Place a dressing.  The first 24 hours after an I&D, the abscess will continue to weep, so it is nice to have an occlusive dressing to prevent he wound from weeping all over clothes and bedding and the inmate’s roommate.
9. The next day, remove the packing.  Since the packing is a foreign body, it should be removed as quickly as possible.  Notice that this abscess seems reasonably dry after one day.  If the wound were still draining pus, that might mean that I had not fully cleaned out the abscess interior, and I might need to re-explore the abscess to see what I missed.
10. Leave the abscess open.  Patients at this stage can shower and I encourage them to let the water wash out the interior of the cavity.  Over the next week or two, the abscess will heal in from the bottom out.
11. Antibiotics? There is a large body of literature that says antibiotics should not be routinely prescribed for MRSA abscesses as long as they can be fully drained and as long as the patient is otherwise healthy and there is no accompanying cellulitis.  This patient is healthy and I see no cellulitis surrounding the abscess, so I am not going to use antibiotics.

This entire procedure took literally about 10 minutes to do.  It turned out well.

ADDENDUM (12/12/12)  This is a picture of the site one week post procedure.  It appears to be healing well.  The skin rash reaction to the dressing tape looks worse than the wound!

Mandatory disclaimer:  The technique I used here is a result of my Emergency Medicine training, my experience and my preferences.  Other practitioners may use other techniques that are just as effective.  Some may even disagree with what I have said here!  You should develop your own technique based on your training, experience and preferences!  A very good official source for the technique of abscess I&D is Roberts: Clinical Procedures in Emergency Medicine, 5th ed.  Chapter 37, Incision and Drainage.  Also, I am talking here about simple abscesses.  Abscesses in complicated areas such as the hands, neck or anus or abscesses of the face where the inevitable procedural scar will be visible may be best sent to a specialist to drain.

Do you have a different technique that you use to I&D abscesses?  Please comment!