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"The test is negative... discharged!" Occult EM - test negative misses

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In the spirit of EMED's great "its probably nothing, fast track disasters" thread, I've thought of a similar ongoing thread topic that I hope will provide some more good learning content and food for thought.  I've found that a lot of newer students / interns / APPs (myself included) often fall into the trap of thinking, "well, the tests are all negative, so that's all there is to it" and discharge the patient.  "What else could I even do for this abdominal pain patient with negative labs, CT, etc... surely we've ruled everything out!"  

Well, I've been spending a lot of time with our ED quality committee, aka morbidity and mortality team, which reviews high risk cases and misses that have went through the group... it really has been a great learning experience - I'd recommend everyone check it out if they haven't yet. The line of thinking noted above is a common pitfall that we see, because there are still emergencies that can be missed even after the "standard workups" come back negative.   

With that in mind, I made an evernote document on my phone about a year ago where I've been keeping track of situations that arise in practice that fit this general theme...  I've got it organized like this:

The situation --> the negative test --> it can still miss XYZ targeted ddx for relevant emergency medicine conditions --> so, what to do (and don't forget that you need to document in the MDM to say why you don't think those are occurring--> why its important, or what are the risks of missing those conditions.

Here's a classic example:

FOOSH injury --> triage ordered hand and wrist X-rays that are negative --> ddx:  occult scaphoid fracture, elbow fractures, proximal humerus fractures --> plan: examine those areas, X-rays other areas if needed, rarely advanced imaging if very high suspicion, otherwise place in thumb spica splint and follow up in 1 week for repeat exam and repeat X-rays --> Why? Because missed scaphoid fractures are a common miss and lawsuit potential because of the bad outcomes and chronic issues that result from them. 

 

..................................................................................................

Alright team, in the same fashion as Emed's thread, lets see how you do with a few of the cases I've complied... 

1) elderly fall from standing with back and hip pain and not ambulating --> back and hip X-rays negative --> whats your ddx / plan / thoughts / reasoning?

2) closed head injury with significant mechanism, noting head and neck pain --> CT scan head / neck is negative --> ?

3) soccer injury - traumatic knee pain and swelling, unable to ambulate --> knee X-rays negative for fx --> ?

4 - A) RLQ abdominal pain and tenderness in a 23 yo M x 6 hours --> labs, CT scan neg --> ?

vs

4 - B) RLQ abdominal pain and tenderness in a 23 yo F --> labs, preg test neg, CT scan neg --> ? 

5) Periumbilical and epigastric abdominal pain in a remote roux-en-y gastric bypass patient --> labs and CT negative --> ?

6) infectious / viral syndrome (fever, congestion, cough) with pleuritic chest pain --> CXR negative --> ?

 

Theres probably no specific right or wrong answer to these, but let me know what you'd include for answers and I'll share mine, and hopefully we'll all learn as a result.  I've got quite a bit more where these came from... would love it if others would share similar situations that they encounter to make this an ongoing learning thread.  

-SN

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1. CT Lspine & CT pelvis.  Admit.  Yes, I know MRI is more sensitive, but I can't get that from the ED at my facilities.

2. Need more info: age, anti-coag status, any hx of neuro issues, (common in my area), any hx of being a DST (drug seeking troll?)

3. Confirm good distal neurovascular status, d/c with knee immobilizer, crutches, pain meds, NSAIDS, ortho f/u next day.  Likely needs an MRI - again, that I can't get from ED.

4 & 4.  D/c with good return instructions.  PCP f/u next day - or return to ED next day if no PCP.

5.  Big can of worms: consult the gastric bypass surgeon - in my experience gen surg won't go near this.

6. Eval for PE risk factors, document PERC and/or Wells as appropriate, CT PE if indicated.  Would get cultures in case of occult PNA.

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a recent one seen by one of my partners at rural gig:

child with fever, neck pain & stiffness, wbc around 12, low grade fever, nl lp.  strep and mono neg.

missed dx? retropharyngeal abscess requiring ent percutaneous drainage. fortunately child was admitted as "probable viral meningitis" and the peds intensivist made the dx.

P.S thread made a permanent thread. great idea for a topic serenity!

 

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Patient I had a couple of years ago:

Older male presented with acute onset shortness of breath and pleuritic chest pain.  HR 110-120's, actively being treated for cancer and had been discharged from the hospital the week before after an extended admission.

Triage nurse decided to try and be helpful and sent a d-dimer before the patient was seen by a provider, which is negative.  

The patient with the negative d-dimer had multiple segmental PE's on the CTA.  Takeaway point for new grads especially; d-dimer is only useful when used in conjunction with proper risk stratification.  If your pre-test suspicion is high enough, the dimer result is irrelevant.  

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M25- indeed. I have seen this a few times. d-dimer peaks then returns to baseline after a week or so, even if clot persists/grows.

also remember to age adjust d-dimers. if you are 90 yrs old you need a dimer > 0.9 to be +, not > 0.5.

also if you make the mistake of ordering a dimer on a pregnant pt, nl range is twice expected .

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-Great case and perfect example of this theme, E.  Keep em coming...

 

-Nice job Ohio!  Here are my takes on the first 3...

 

1) elderly mechanical fall from standing with back and hip pain and not ambulating --> back and hip X-rays negative -->  ddx: occult hip fx, knee pathology (often refers to hip pain), cauda equina syndrome

--> plan:  do a good exam of back, hip (log roll, axial load), knee.  Determine need and location for advanced imaging.  Preferable to do MRI, but if you don't have it, CT pretty good for hip, but is not good for cauda equina workup.  If all ruled out, may still need admission for fall risk / ambulatory dysfunction / PT eval. 

 --> Why important?  Because occult hip fx, if its missed and it displaces, will cause osteonecrosis from poor blood supply and has poor outcomes. 

 

2) closed head injury with significant mechanism, noting head and neck pain --> CT scan head / neck is negative -->  consider basilar skull fracture (https://www.ebmedicine.net/topics.php?paction=showTopicSeg&topic_id=96&seg_id=1831and cervical / vertebral artery dissection - both could be missed by non contrast CT scan

--> plan:  clinically evaluate for both of them.  basilar skull fx (csf leak, battle signs, etc) and dissection (vertigo, neuro sx, neck bruit, neuro exam) --> if present, consider CT angio head/neck for dissection.  

 

 

3) soccer injury - traumatic knee pain and swelling, unable to ambulate --> knee X-rays negative for fx

--> ddx:  non displaced tibial plateau fx (if point tender, can get CT)

quads / patellar tendon rupture (can they extend knee and lift off the bed?)

dislocation with spontaneous reduction - vascular injury risk - good neurovasc exam

compartment syndrome - rare without fracture but document good exam

--> plan:  once all ruled out clinically, d/c with knee immobilizer, crutches.  May need an MRI as outpatient.  

 

 

Anyone else have thoughts on the final 3?

 

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First time, long time. I'll give it a shot - lemme know if this is what you were getting at, Serenity.

4a - biggest suspicion in a young male with RLQ pain w/out any abdominal pathology on CT imaging would be testicular pathology that can often present w/ tenderness and pain in the lower quadrants. So do a good genital exam and consider US for a torsion vs epididymitis r/o. 

4b - similar for a young female - while a negative pregnancy test obviously r/o an ectopic, the biggest "miss" here would be ovarian torsion that requires an ultrasound to demonstrate poor doppler flow. Ideally a TOA would be seen on CT. 

5 - gastric surgery patients are scary, but this is perhaps a anastomotic ulcer and the patient may need an endoscopy in the near future. 

6 - pleuritic chest pain has me thinking PE > PNA > pericarditis. I think with infectious symptoms it could be PNA that was missed on CXR or pericarditis, though the viral syndrome could be a red herring, so PE should at least be thought of and Wells/PERC criteria calculated. Consider D dimer if low to moderate risk, CT PE if high risk. Maybe it's just good old pleurisy (which I typically treat as a diagnosis of exclusion). 

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Had a great peds case the other day.10 yo male with perimumbilical pain rad to rlq x 1 day. normal gu exam . call surgery due to high suspicion and was late in day on sunday. wbc 20000 crp 9 us came back normal visualized  appendix?? surgery called and signed off ... patient still very tender . mri obtained . the diagnosis ? acute gangrenous appendicitis . not sure what they were looking at on ultrasound . weird thing was that the radiologist didnt hedge at all . usually its an equivocal read like appendix not definitevly visualized so kinda odd 

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Right on the money, @drybones.

 

Great case @YoungH89and another great example of this theme.  That is actually getting at the same pitfall as problem #4.... while imaging is pretty good in appendicitis eval, its not by any means perfect.

 

 

Here is my take on the last 4 cases...

4 - A) RLQ abdominal pain and tenderness in a 23 yo M x 6 hours --> labs, CT scan neg --> DDX: testicular pathology (examine them) and appendicitis is still on the ddx even after negative imaging.  CT is not sensitive to rule it out, especially early in the course, so you still have to consider it undifferentiated abdominal pain at this point.

--> Plan:  if high suspicion, should consult general surgery, consider admission for serial abdominal exams.  I've seen MRI done in high suspicion peds, but perhaps this is possibility in adults too?  If lower suspicion, recommend 12 hour abdominal repeat exam, either by primary or return to ED.  DONT tell the patient that they don't have anything bad going on with them (a common pitfall that helps the plaintiff attorney bury us).  

 

 

4 - B) RLQ abdominal pain and tenderness in a 23 yo F --> labs, preg test neg, CT scan neg --> ddx:  PID / TOA, ovarian torsion.  --> plan:  get a sexual hx, do a pelvic exam, consider pelvic ultrasound.   A case very similar to this was the topic of a great discussion on an emrap bouncebacks case a while back, definitely worth the listen if you've got a subscription.  https://www.emrap.org/episode/april2010/bouncebacks  It was also in Mike Weinstocks book Bounceback's Medical and Legal which I recently finished reading and was fantastic - highly recommended https://www.amazon.com/Bouncebacks-Medical-Legal-Michael-Weinstock/dp/1890018740

 

 

5) Periumbilical and epigastric abdominal pain in a remote roux-en-y gastric bypass patient --> labs and CT negative --> ?

This is something I actually covered in my residency blog on November 2015 after we had a great lecture from a bariatric surgeon.  I'll copy/paste the relevant section here, but if you're interested in more background info, check out the blog (link is in the signature below my post).

-Make sure that, in general, you are using PO contrast when CTing these patients, and a short prep (one or two cups 30 min before the scan) is okay if you're not as concerned for bowel obstruction, since it won't take long getting the contrast to the stomach / proximal bowel... this will increase the sensitivity of CT scan.  

-90% of the time that a bariatric patient complains of abdominal pain long after their surgery, its either GALLSTONES or a peri-bypass ULCER that can be treated with standard conservative therapy (PPIs, maalox, etc).

-The other 10% of the time, it will be either an INTERNAL HERNIA (tough dx to make, can be intermittent.  They may only complain of bloating, but this is still a very dangerous condition that can lead to bowel necrosis; CT is not sensitive to rule this out, so call the surgeon every time) or STRICTURE/BOWEL OBSTRUCTION (do not put an NGT into any bariatric patient!

--> plan:  clinically rule in/out a bowel obstruction, consider RUQ ultrasound, consult the bariatric surgeon to discuss the case and the risk / potential for internal hernia and outpatient plan.  Surgeon will often say that patient needs a close outpatient EGD.  

 

 

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Great post! To test myself these are my answers without looking at any of the responses... 

 

1) elderly fall from standing with back and hip pain and not ambulating --> back and hip X-rays negative --> whats your ddx / plan / thoughts / reasoning?

 

First of all I would go back and re-examine the patient more thoroughly especially a neurological examination. I would absolutely get a CT at this point... I have seen XRs miss fractures all of the time. maybe a CT of the lumbar spine and a CT of the pelvis and femurs. If these were negative I would probably get a PT consult and have the patient admitted. 

 

2) closed head injury with significant mechanism, noting head and neck pain --> CT scan head / neck is negative --> ?

 

What’s crazy is in my ER I have never been told by one of my attendings to get an MRI if CT is negative for cervical spine fracture. I would definitely consider MRI in this patient depending on the severity of symptoms. Could this be something vascular? Maybe a CTA neck to rule out dissection.

 

3) soccer injury - traumatic knee pain and swelling, unable to ambulate --> knee X-rays negative for fx --> ?

 

Providing there are neurovascular deficits (ie palpable popliteal pulses) I wouldn’t do anything but knee immobilizer, crutches and Ortho follow up... we don’t do MRIs for this kind of stuff in my shop although I wish we did. Also I would be making sure on my examination that there was no hip pathology referred to the knee. 

 

4 - A) RLQ abdominal pain and tenderness in a 23 yo M x 6 hours --> labs, CT scan neg --> ?

 

Always do a testicular examination! This patient would get a urine and a scrotal ultrasound for sure. 

 

4 - B) RLQ abdominal pain and tenderness in a 23 yo F --> labs, preg test neg, CT scan neg --> 

 

I would definitely do a pelvic examination along with all the swabs. I once had an attending tell me that it makes sense to treat any female with unexplained abdominal pain for STDs so depending on suspicion I may send the patient home after Rocephin with an RX for doxycycline and metronidazole and OB follow up. They wouldn’t go home without a pelvis US either! They would also get very strict follow up and return precautions understanding that a CT could miss appendicitis. 

 

 5) Periumbilical and epigastric abdominal pain in a remote roux-en-y gastric bypass patient --> labs and CT negative --> ?

 

I would make sure that CT scan involved P.O. contrast and if not, rescan them. I would always call their surgeon no matter what. Could this be an aortic abnormality? If so maybe a CTA. I would also consider cardiac ischemia so I would throw on a cardiac panel.

 

 6) infectious / viral syndrome (fever, congestion, cough) with pleuritic chest pain --> CXR negative 

 

I would ask about PE risk factors. If low risk (no OCPs, no cancer, no recent travel, no tobacco use, no recent surgeries, mo coagulation disorders, no recent pregnancy, no family or personal VTE history... also did you know cocaine makes people prothrombotic?!) and my suspicion was low I would get a D Dimer. If high I might just go with a CTA chest. Myocarditis and pericarditis can present like this so this patient may also get a troponin and EKG.

Edited by ERCat
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Thanks for replying ERCat!  Good answers too.  The more perspectives, the better.

 

I'll share a few more cases that have come up.... keep on guessing folks, and feel free to share away your own!

 

7) 42 year old M comes in with hand and finger pain after falling last night while drinking, she doesn't remember the details, hand and pointer finger are swollen and painful --> triage hand/finger X-rays negative --> ? ddx / plan / why?

 

8 )  32 year old F comes in with a new / unique headache compared to her prior migraines --> head CT negative --> ? (this is almost a trick question but bear with me)

 

9) 32 year old F comes in 3 days postpartum with a severe headache --> head CT negative --> ?

 

10) 87 year old F comes in immediately after a mechanical fall with head injury, on warfarin, is asymptomatic --> CT head / neck negative --> ?

 

 

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#8 (assuming it's not the same pt as #9)

Different how? Any neuro findings on exam?

Consider IIH (especially if overweight), SAH (given suspicious historical features) or infection. Either way, LP could tell us a lot. Ocular u/s can assess for papilledema if IIH suspected.

#9

Reeks of preeclampsia. HTN? Proteinuria? Edema? Abnormal LFTs? Platelets? Visual disturbance?

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Nice thoughts @fishbum.  

 

The answer to the "trick question" of #8 is that the ddx doesn't really change and the real error is the ordering of the head CT in the first place.    Head CT really rules out very little in a non traumatic headache patient.  The test is still for some reason part of the "standard workup" for so many docs/PAs/NPs.  I think it actually hurts our case when a well appearing patient who you think will be fine has a "just to be safe" head CT come back negative and you go on to discharge the patient... would have been better off not ordering it at all.  We have these discussions on our M&M / quality committee all the time... the plaintiff attorneys say things like "the PA clearly knew something was wrong so they ordered a head CT, but they didn't know how to finish the workup to confirm the diagnosis".  The test begets a follow up test if it is negative, like an LP, CT angio, MRI, etc etc.  So, I am always careful about first thinking what it is on the ddx that I am able to clinically rule out, what specific disease I am still considering, and what rule out tests that needs.  CT is almost never the sole answer... so be careful with it!

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Learned another good one on emrap today!

 

68 year old F with PMH of a fib presenting with abdominal pain and benign exam --> lactate and CT abdomen pelvis w IV contrast negative --> ??

 

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Need CTA angio for assessment of mesenteric ischemia. 

CT with IV contrast only tests one arterial phase, but need venous phase as well to further assess for mesenteric ischemia.

It is a good thing lactate is negative. Positive = bowel ischemia aka probably too late for meaningful intervention.

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Bingo!  I had always been taught that while CT w IV contrast wouldn't pick up the specific clot location, it should still show you secondary signs of ischemia and thus if its negative you can stop there (wrong - it would only pick up late stage ischemic changes but by that point it is too late).  I had also been told that negative lactate helped to rule it out (wrong - again only a late stage marker).  I also had been taught that the CT angio requires a huge contrast load and despite that it has a different focus so you might miss things you'd otherwise see if you got a normal CT w IV contrast.... all that being said I only very rarely see it ordered.  

The emrap episode turned that one on its head!  They explained that CT w IV contrast is NOT sensitive to rule out signs of ischemia, so even if it is negative you can't rule it out.  They also said that ordering CT angio has only minimally increased contrast bolus, not significantly increased risk for AKI, and it has two scans so the rads will still get the normal CT with IV contrast images to assess for everything else.  Lesson learned!  I'll be ordering more CT angio abd pelvis on my elderly abdominal patients now!

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Yes I had very similar prior teachings, and didn’t know the differences between the CTA and CT with IV contrast until this month’s Urgent Care RAP has a segment on mesenteric ischemia.

A side note from this discussion, but there is a significant amount of literature now showing that IV contrast as used in today’s practice does not increase risk of kidney injury in patients with baseline normal renal function. More studies needed on those with baseline renal insuffiency, but at this point I give almost all patients who have normal kidney function at baseline IV contrast as it helps with evaluation for many more disease processes than a non-contrast study.

Still need to be very careful with gadolinium contrast used in MRI studies in patients with any renal impairment as it can lead to neohroenic systemic fibrosis (aka contrast is deposited in skin with high morbidity and mortality).

I know this post is getting long, but I can’t give a high enough bump to the comment about CT as having very little utility in non traumatic headache. I find often I get push back from physicians on new onset, persistent vertigo patients with HINTS central exams who recommend CT first, which is frustrating as it is the wrong study and leads to unnecessary radiation and often useless information. I haven’t found a posterior circulation stroke yet (only had MRI indicated on 3 patients), but did find central causes in each case that I did order the MRI (first diagnoses of MS with demylinated nerves, posterior encephalopathy 2/2 chronic uncontrolled hypertension). For full discussion or vertigo workups, EMRAP has a great C3 episode as well as September 2017 and April 2018 episode segments.

Edited by LA_EM_PA
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High impact mvc with abdominal pain and tenderness --> CT scan with IV contrast is negative.... patient is obnoxious and bothering nurses, so they keep asking you, "can you just discharge him already?!".    What can still be missed, and how do you proceed?  (saw this case in residency)

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Tox issue or gastric issue? 

spinal injury of some kind? 

referred pain from an injury in the torso?

rectus abdominis tear?

I'm guessing you are looking for something only appreciated on MRI...

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In addition to EMEDPA suggestions:

Bladder rupture? I can’t recall immediately off the top of my head the diagnostic test, but would likely see on CT I presume.

True feel seatbelt sign would be concerning for spinal cord injury? Also can usually catch on CT but MRI next step of concerned.

Could patient walk? Pelvic fracture with referred pain/bleeding into abdominal cavity?

And by bothering nurses is he altered/showing signs of shock (presumed hemmhoragic)?

Abdominal compartment syndrome? (A diagnosis that I will admit freely I know by name but not much pathophysiology or workup)

Edited by LA_EM_PA
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Hey I learned some things too!  I hadn't thought of some of those but they are all great answers.  This case happened to be a hollow viscous injury, which is notoriously difficult to diagnose in blunt trauma because of the low sensitivity on CT scan.  The thought is that the traumatic perforation causes the bowels to spasm and it won't actually spill bowel contents until several hours later.  The trauma surgeon evaluated this patient, admitted them for serial exams, and ended up taking them to the OR several hours later since the patient developed worsening peritoneal signs.  Don't be fooled by the negative CT if they have real tenderness / guarding!  

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