“Do you know the four A’s of being a great emergency physician?” a colleague asks. He just overheard you giving your “It’s a virus” lecture to a twenty-something with a bad URI and no PMD to call her in a useless prescription for Fogmentin or Maxiﬂoxicin.
“What are they?” you respond, certain that the response will be unsavory.
“In decreasing order of importance, they are Availability, Affability, Ability and Antibiotics,” he responds. “Though some would say that antibiotics trumps both ability and affability.” Fifteen minutes later, you break free of the fog surrounding you and go see your next patient, a 35-year-old man with an obviously red and swollen elbow. After asking the typical questions, you surmise that he has had about three days of gradually worsening redness, swelling, pain and “ﬂu like symptoms.” Today he felt feverish, so he took his temperature and it was “109.”
“Do you mean a hundred point nine or a hundred and nine point zero,” you ask, hoping it will lead to some clarification.
“Yeah,” he answers. You suppress a groan and try again.
“Was it one hundred point nine, like this?” you say, writing it down on the bed sheet so he can see it.
“I think so,” he answers. You decide that it really doesn’t matter that much and proceed to examine his elbow. The elbow looks red, swollen and angry. He has a lot of pain moving it even a little bit. It doesn’t appear to be the more common septic bursitis so you ﬁgure he probably has a septic elbow and needs his joint tapped. You explain the procedure and your additional concerns to him and then go off to order some labs, get consent for the procedure, and ask the nurse to give the fourth “A” of being a great emergency physician. Oh, and some analgesia – your colleague forgot the most important “A”! About 20 minutes later a nurse approaches you and says, “The guy with the elbow, won’t sign the consent. He says he’s afraid and just wants some antibiotics.”
When you re-enter the room, the patient says, “I don’t want to be a pain in the ass, Doc, but can’t you treat me without sticking a needle in there? I don’t think there’s any ﬂuid there. I had a knee infection once and they didn’t have to drain anything; they just gave me the bug juice.”
“How about if we take a look with an ultrasound machine to see if I’m right or not?” you answer.
“OK,” he begrudgingly concedes.
About five minutes later you return with the machine, probe and KY jelly (someone lost the ultrasound gel again). You obtain the following images, plus some comparison images of the normal elbow.
What do you see? Is there a drainable ﬂuid collection? Continue in the following.
Dx: Evidence of Free Fluid Visible on Ultrasound
The image is of the elbow joint in approximately 90 degrees of flexion with the probe just posterior to the lateral epicondyle. The cortex of the radial head and lateral epicondyle of the humerus are somewhat hyperechoic (white) with some posterior shadowing, especially behind the lateral epicondyle. Between these two bones and within the joint, there is evidence of free ﬂuid, which appears hypoechoic (dark).
A picture is worth a thousand words when it comes to obtaining an informed consent. After seeing the difference between the normal and abnormal elbow ultrasound, your patient concedes and agrees to let you drain his septic joint. He signs the consent form; you set up for a sterile procedure, and a few minutes later the nurse is sending some cloudy looking ﬂuid to the lab for analysis. Back on track, you look for your colleague to let him now you have the “ﬁve A’s” down as well as the “U” for ultrasound.
Pearls & Pitfalls for Ultrasound Evaluation of Joints
1. Use a High Frequency Linear Transducer: Typically, because they are such superﬁcial structures, joints are best visualized using a 7-10 or 10-13 MHz, linear array transducer. For the elbow, start with your probe in the dimple between the olecranon, radial head and lateral epicondyle on the lateral side of the elbow.
2. Use Adequate Analgesia: Scanning over an inﬂamed joint may be painful for the patient. Pretreat with opiates as long as your patient will be admitted or has someone to drive them home.
3. Ceate a Good Acoustic Window: To get the best image, you may need to apply a little extra gel over bony areas or scan the joint while it is immersed in water.
4. Be Thorough: if you don’t see ﬂuid when you expect it, consider trying a different contact spot for the probe or repositioning the joint. Often, the more the joint is bent, the easier it will be to ﬁnd excess ﬂuid.
5. Compare Sides: Because most people have two elbows, any questionable ﬁndings on one side may beneﬁt from a comparison view of the other elbow. Look for dark, anechoic ﬂuid, which should not be visible by ultrasound in a normal joint.
6. Review Your Anatomy: Utilize color Doppler or spectral Doppler to ensure that the anechoic ﬂuid collection you are visualizing is not a vascular structure. Reviewing your musculoskeletal anatomy beforehand will help you identify the bones, tendons, muscles, nerves, and bursae you see on your bedside scan.
7. Consider Routine Ultrasound Prior to Tapping a Joint: Not only will this help improve your musculoskeletal ultrasound skills, it will also help you avoid wasted time and unnecessary risk and pain for your patient when there is actually no ﬂuid collection available to tap.
8. Practice: With bedside ultrasound, there’s no substitute for experience. The more scans you do, the better you will be able to differentiate abnormal from normal – even when you are unsure exactly what the abnormality is. To view a library of ultrasound images, go to the Ultrasound department within www.epmonthly.com.