The biggest challenge in diagnosing septic arthritis is to think of it. Once you think of it, there is a diagnostic process that you activate. The second biggest challenge is that that diagnostic process we learn in training is flawed. We have no alternatives right now, so I will share with you my thoughts on how we should use our judgment as clinicians.


Triggers to consider septic arthritis essentially are the same triggers as infection anywhere. Celsus’ cardinal signs of inflammation are dolor (pain), calor (warmth), rubor (redness), tumor (swelling). Some authors have written that fluor (flow) should be the 5th cardinal sign and in this case the effusion is one of the most important clinical signs.


The detection of effusion at the bedside has been covered elsewhere but includes inspection, palpation, and milking. Smaller volumes of fluid are harder to detect. Ultrasound can be utilized to improve our accuracy.


The clinician generates hypotheses at the bedside and then circles back to revisit risk factors. This is an underappreciated process that deserves more attention. The following risk factors have high specificity:



-joint surgery (mainly recent)

-joint prosthesis (at any time)


There are others but those are the main ones. You might think of it as “compromised immune system” and “compromised joint.” If it helps you in remembering this, recall that the synovium is a vascular tissue. It lacks a basement membrane (which tends to filter out bacteria in other tissues, like the cornea). The joint relies on the immune system to protect us from bacterial translocation. Recall also that bacteria love to find crevices to hide in. A disrupted joint, or a compromised immune system creates the setting for septic arthritis.


They don’t all have to have those high risk features though. Often the clinician is left with enough suspicion to pursue a risk stratification process before considering a tap. In low risk patients that process can involve inflammatory markers (traditionally WBC, CRP, ESR, with emerging roles for procalcitonin and perhaps other markers) to lower your suspicion back below the threshold of further testing. I recommend you use as many of these as you need to reassure you in a low risk patient that there is no infection. All of them have limitations but if the results are normal, you are greatly reassured.


For patients where doubt continues to exist, the diagnostic pathway for septic arthritis ends in arthrocentesis, though its results may be less clear than we realize. Common practice is to use synovial blood counts (often 50K) as disease-defining, which does not actually work very well. Synovial WBC cutoffs at all levels will both miss and overcall septic arthritis. Even if you use the cutoff as 25K, it still misses as many as 1/4 of all cases, one prospective study said it would miss more than 1/3 of all cases (Margaretten JAMA2007). Meanwhile there will continue to be patients with WBC above 50K who have other causes (gout for example).


The gram stain sensitivity is as low as 40% (Ross Infect Dis Clin North Am2017). If you have strong suspicion based on risk factors, drain the joint and have them follow up in 24 hours, giving antibiotics while awaiting culture results.



-Septic arthritis is considered when the patient has an inflamed joint (effusion, warmth, pain).

-Inflammatory markers, if all normal, can lower your concern enough in a low risk patient to rule out disease.

-Risk factors (compromise of joint, compromise of immune system) may be more important than the other tests.

-Synovial WBC has significant limitations in sensitivity and specificity, and is not a disease-defining reference standard.


Selected References:


Septic Arthritis of Native Joints.

Ross JJ.

Infect Dis Clin North Am. 2017 Jun;31(2):203-218. doi: 10.1016/j.idc.2017.01.001. Epub 2017 Mar 30.


Does this adult patient have septic arthritis?

Margaretten ME, Kohlwes J, Moore D, Bent S.

JAMA. 2007 Apr 4;297(13):1478-88. Review.

PMID: 17405973



A patient presents with redness and swelling. There had been a wound there 2 weeks before and the patient is worried about retained foreign body. Xrays are negative for foreign body. The student tells the patient “Good news! The xrays show there is no foreign body there!”


You wince a bit. Every mature clinician must know the limitations of the tools they use. I want to take a divining rod to the beach and see if it knows which direction is the ocean. If it doesn’t, that doesn’t mean the ocean is a mirage. It means the tool doesn’t work perfectly.


You clarify the student’s comments. The xrays do not show there is no foreign body. Instead they merely are negative. You manipulate the swelling and it reproduces pain. That is the hallmark of an infected foreign body (or any sharp foreign body, infected or not). Alas, anything infected hurts when you manipulate it, so this rule is not very specific.


You tell the patient there could be a foreign body there. You ask more about the history and it turns out there could be some plastic in there. Ultrasound is suggestive enough that you choose to dissect, and indeed uncover a broken piece of plastic.



-Always acknowledge the limitations of imaging studies (or any studies)

-Foreign bodies are suggested by pain with manipulation


A patient presents with a mid forearm fracture. Reduction is tough because it is 100% displaced. Unlike distal fractures, you can not grab the bone as it is surrounded by muscle. It is hard to pull enough traction to reapproximate. Now what?


Try angling more during your reduction, exaggerating the angulation. Now it is slack enough you can put the distal piece on the proximal piece. Use your other hand to guide it on manually. Once the two pieces touch each other, simply straighten the bone out.


You try this and are able to secure adequate reduction. The patient now has a better chance of receiving adequate reduction without surgery.



If you can not pull traction to reapproximate fractures, try angling the fracture to give it slack, then fit the fragments together before restoring alignment.


A patient presents with a rash. In emergency medicine we often recognize certain rashes at a glance, like urticaria or a viral exanthem. This does not fit any of those. The patient is scratching vigorously. Is this atopic dermatitis, commonly known as eczema?


Eczema might be the most common rash we see in the emergency department but its presentations are diverse so it is not always a “know it at a glance” diagnosis. We can get tricked. The etymology of eczema is “out boiling.” which describes that rash that is papulovesicular with erythema and weeping and crusting. A lot of rashes do that of course.


Atopic dermatitis is a special disease that arises from a defect in the epithelial connections between cells. When you understand that, you can diagnose it, and you can treat it.


The epithelial defect leads to microscopic “holes” in the skin. Water gets out, and irritants get in. Itching is dramatic.


Here is how you diagnose atopic dermatitis in the emergency department:

-Pruritus is a must

-The classic inflammatory rash of eczema (papulovesicular with erythema and weeping)

Allow for hyperkeratosis if the lesions are subacute or chronic

Allow for findings of excoriation


So far that hasn’t nailed down the specificity yet. Any inflammatory rash will do all that. Poison oak, for example will do the same thing.


Add in the specificity with:

dry skin by history or current presentation (defect in skin barrier)

distribution is flexural or hands by history or current presentation (areas of trauma and friction)

-history of atopic diseases or childhood onset


Now that you have the diagnosis, it is all about restoring hydration, and restoring the skin barrier. Have them take baths, hydrate the skin, and then lock it in with ointment. Teaching that will empower them to be less reliant on steroids.



-Suspect atopic dermatitis by severe itching and an inflammatory rash

-Localizes to areas of friction (hands or flexural areas)

-Dry skin prominent

-History of allergies or asthma

-Usually childhood onset


A patient presents with respiratory distress and COPD. She is very dramatic in her gestures, very upset and emotional. The first time you saw her you had given her lorazepam and sent her home. It turns out she frequently gets that. You and your colleagues eventually set boundaries on that but she continues to present daily for respiratory distress. This case turns out to involve the deeper human side of medicine. How do you access that?


How do we not only know medicine but know the human condition? Read Shakespeare? Go to bedside medicine skills sessions with actors? Do an ED fellowship in emergency psychiatry?


I particularly enjoyed reading the articles by Frederick Platt from the University of Colorado. He was an internist who would put on workshops on difficult patients/encounters. In role playing, the clinician would learn to recognize strong affect, stop, and name the affect. “I sense you are feeling…upset…scared…angry…etc.” The patient then is invited to explain their fears and concerns.


Emotions, as the Latin root “motere” tells us, serve to “move” us. They motivate us and impel us to action. They are faster and more intuitive than verbal language. But they are not enough for us. We need to move the patient from nonverbal to verbal expression.


“I sense you are feeling scared.”


The patient starts crying. You ask why she is scared.


She is afraid of dying.


You then address that fundamental concern with her. You write “fear of death” as the diagnosis, knowing that future providers can at a glance review the primary diagnosis for each visit. As your colleagues and you empathetically address her concerns, the visits drop from daily to weekly to a couple times a year. She starts taking care of herself better and gets off the sedatives.



-if there is strong affect, stop, name it, and inquire about it

-transition the patient from nonverbal to verbal communication

-identify the concerns and needs behind each visit with a question like “what concerns you the most?”

-review the post on agenda setting for related suggestions


Patients often lie about drug use and that can interfere with care. Part of practicing emergency medicine is using skill in communication to get through those communication pitfalls.


To get patients to tell the truth on drug use, start with asking about past use. Then ask current.


Furthermore, sometimes it helps to ask the question specifically In my area, I tend not to ask “do you use drugs?” I ask “did you try amphetamines when you were younger?”


If they answer affirmatively then can expand to “when was the last time?”


If you have doubts about their answer, you can say “may I test your urine and confirm?” Their response is often revealing.



-Ask about past drug use first

-Then ask about recent drug use

-Ask permission for a drug screen


Templates do not just facilitate documentation but also can guide bedside observations. The person taking a history who uses OLD-CARTS might be reminded to ask a dimension of a symptom that otherwise would not have been elicited.


What does it mean to say a child is “well-appearing” or “ill-appearing?” I find the GCS (Glasgow Coma Scale) categories to be helpful:


Eyes – is the child attentive with the eyes

Motor – is the child appropriately active/reactive

Verbal – is the level of social interaction appropriate for age (eg comforted by the arms of the mother).


Using GCS can stimulate a more detailed description of what we mean when we describe an ill-appearing child.



-Use the categories of GCS to detail what it means for a child to be “ill-appearing.”


There are two scenarios where you might see non-convulsive status epilepticus (NCSE):

-Presentation of coma

-Failure to rouse after seemingly successful treatment of a seizure (one article said up to 20% of status epilepticus generates NCSE after resolution of the convulsion)


The gold standard is 48 hours of continuous EEG monitoring. Unfortunately at many EDs we rarely can get EEG monitoring at all. Thus we need to be mindful of some subtle clinical signs.


Clinical signs or triggers that might prompt you to consider non-convulsive status epilepticus:

-***history of epilepsy in someone in an unexplained coma***

-volatile vital signs

-dilated pupils

-twitching (disrobe patients. May especially notice this around the eyes, where it is easier to see)



-failure to rouse after seizure could indicate non-convulsive status epilepticus

-unexplained coma in someone with a history of epilepsy should trigger this possibility

-Disrobe the patient and look for subtle signs of twitching

-Consider autonomic signs – vital signs, pupils


Here is a potential airway technique that may help with visualization: hold the laryngoscope in the left hand (the usual) but the right hand, instead of being at your side, is behind the patient’s head. You then move it around until you get the best view. Then you have an assistant hold the head in that spot.


A hospital in Southern California started doing that. The technique deserves some exploration. The work of Richard Levitan reminds us that the airway is most patent in the sniffing position. Extension does not really help but true sniffing position does. Sometimes you think you have enough and you need more.


I have not seen this technique studied but it probably deserves some attention.



-Consider external cephalic manipulation as an analogy to “external laryngeal manipulation” as a way of fine tuning the visualization during a tough intubation


A patient presents with severe sore throat. You wonder about epiglottitis. You know that using a mirror to look at the epiglottis is a great way to check this but are not confident in your skills. What do you need?


Dental mirror – they are cheap, have your ED stock them


Light – can use a headlamp, the kind that are sold in outdoor stores. Get one with a spot beam rather than a flood light. Nice to have regular AAA batteries instead of the medical ones with cords that are always getting lost or damaged


Relaxed patient – explain to them what you are doing and rehearse it once first


Anatomy – have them lean forward, chin out


View – wrap gauze around their tongue. Don’t pull it out but hold it so they don’t have to sustain muscle contraction to keep the tongue out


No gag – not sure topical anesthetics really work. Try to avoid hitting their pharynx with the mirror until you are ready to lift the uvula and look. Have the patient fix vision in the distance. Have them say “eeeeeee.” Have them do slow panting style shallow breathing.


No fog – hydrogen peroxide or hot water will help prevent fogging


You look and it is hard to see. That reminds us the final thing you need – practice!



-Indirect laryngoscopy is a complex hand-eye skill that you can learn

-Get the right supplies and start doing this now. It may really help you one day.